The URL can be used to link to this page

16118 72ND AVE W.PDFIIIIIIIIIIII5594 16118 72ND AVE W 4�5411,4 ADDRESS: (G'r /! 8 � dAIZ- 1p114�J/ TAX ACCOUNT/PARCEL NUMBER: BUILDING PERMIT (NEW STRUCTURE): COVENANTS (RECORDED) FOR: / /D�O /�7f�I//N?� �I .20V1, 0 0&)pU COMP '•9-T m /y�TIvoY ool:�I! ✓1 wkkwi- S&k. 7 / w n14 9 CRITICAL AREAS:- 1?15-- As- DETERMINATION: ❑ Conditional Waiver Study Required ❑ Waiver DISCRETIONARY PERMIT #'S: y e-?lJ-/0!2 DRAINAGE PLAN DATED:6 -367-00 PARKING AGREEMENTS DATED: EASEMENT(S) RECORDED FOR: PERMITS (OTHER): PLANNING DATA CHECKLIST DATED: (a,2 Z-'c0 SCALED PLOT PLAN DATED: 7-20-00 0 11/L7-1 coi SEWER LID FEE $: LID #: 210 SHORT PLAT FILE: -5- <e-! D49 LOT: . z BLOCK: SIDE SEWER AS BUILT DA' SIDE SEWER PERMIT(S) #: GEOTECH REPORT DATED: STREET USE / ENCROACHMENT PERMIT WATER METER TAP CARD DATED: OTH -3-20-9�5 AIA7 rill/0-v rJ CoiHp%i� �i�'/lGc�d LATEMP\DSTs\Forms\Street File Checklist.doc dT`7�i1� Ort�li�4L S al�.if if 119! w 41 '9 U =0 w CITY_ copy..- 3 Lf%t or -f 1"% 14,4- 4Lam" 1530 U01h AV=* NwtmW %ft 200 BODO", waw*qtm OM (425)746-2995 Fax (425) %2-2956 �cCEIVED OCT 0 12000 DEVELOPMENT 11S ERVICEWqj� CIT�OF V"161 CARP d"w riAY O 10 20. 40 1:20 Rockery Plan �� .. :, L. IR-11"M L N T The Thoresen Lot 2 Sequoia Ridge July 12,2000 p��- tei APPROVED BY PLANNING 7Zvd v. 0 cat a�f�[F3farf�� I-o_ =,v a LLJ ■� Fq � � � ■ gar F«�ro�1 �tiF��, ._..��G� C ® r" 1 5 �n §aF 4s c O REIVY � a� 9 APR 2 7 2000�k s�� z DEVELOPMENT SERVICES CTR8g N15 (4 CITY OF EDMONDS m � L Fi R-" ° §$ "M o § 0 - w v N m 00 m� 2N w 10 a o O�Q UP oe V Q cap o w SID 4 , , IL / U3 O cc I I CL 09 CL Cry 'N' / /` ' / // ' `(y.' ate'., /'r, �., �.;'� / rN// •I'l - (� � �I �� -. -, a , // / / / / / / /� // / // 1 1,. !•I` 111,�, a.9a INS Y a z -4, ✓I11 1 ` it \ 3�� oQ HV3H`// / // ., ,,iio' _t NOZ $ 3 ° .L4 I 3.9ELI.1 N I i FIECEIVED SILE NO. _ -) MAR 2 8 2000 Critical Areas Checklist (soils/topography/hydrology/vegetation) 1. Site Address/Location: Nf� Iltrof, A 2. Property Tax Account Number p5- 3. Approximate Site Size (acres or square feet): r. RAeAe So 4. Is this site currently developed? yes; no. -Ve 74-v-1!4T it/ A44- ".eV e If yes; how is site developed? 5. Describe the general site topography. Check all that apply. / 3g, qj h 54; FT) Flat: less than 5-feet elevation change over entire site. ! ''A 2 ' Rolling:. slopes on site generally less than 15% (a vertical rise of 10-felt oyr.a _ horizontal distance of 66-feet). �•::: ;....... . Hilly: slopes present on site of more than 15% and less than 30% ( a vertical rise of 10-feet over a horizontal distance of 33 to 66-feet). Steep: grades of greater than 30% present on site (a vertical rise of 10-feet over a horizontal distance of less than 33-feet).. Other (please describe): 6. Site contains areas of year-round standing water: ;Approx. Depth; 7. Site contains areas of seasonal standing water: ; Approx. Depth: What season(s) of the year? I' 8. Site is in the floodway zW floodplain 40 of a watercourse. 9: Site contains a creek or an area where water flows across the grounds surface? Flows are year- round? Flows are seasonal? (What time of year? j ). 10. Site is primarily: forested ; meadow ; shrubs - mixed urban landscaped pawn,shrubs etc) .*-0" she /ZdPosiAIj . J�Rur✓ ; 11. Obvious wetland is present on site . �Et�v�" A,�p� '� For City Staff Use Only .I Site is Zoned? - /� • �(7 �. Rr00&"3 IB9'J•1990 City of Edmonds' I Critical Areas Checklist The Critical Areas Checklist contained on and submit it to the City. The ty City will. this form, is to be filled out by any person review the checklist, make a precursory site preparing a Development Permit visit, and make a determination of the Application for the City of Edmonds prior subsequent steps necessary tol complete a to his/her submittal of a development- development permit application. permit to the City. With a signed copy of this fotm, the The purpose of the Checklist is to enable applicant should also submit vicinity map City staff to determine whether any or plot plan for individual lots of the parcel potential Critical Areas are or may be with enough detail that City can find present on the subject property. The and identify the subject pareei(s). In information needed to complete the addition, the applicant shal include Checklist should be easily available from other pertinent information I(e.g. site observations of the site or data available at plan, topography map, etc. ' or studies in City. Hall (Critical Areas inventories, maps, conjunction with this Checloist to assist or soil surveys). 'staff in completing their preliminary assessment of the site. An applicant, or his/her representative, must fill out the checklist, sign and date it, I /� ACI&A.�1e ALO�✓4' Ti!L°I i �� /n I have completed the attached Critical Area Checklist and attest that the answers�rovided are factual, to the best of my knowledge (fill out the appropriate column below): Owner / Applicant: Applicant Representative: Name Street Address Street Address City, State, ZIP Phone City, State, ZIP I Phone gnature Date Signature . Date i I ' CRITICAL AREA STUDY SEQUOIA RIDGE Edmonds, Washington /f Prepared for David Evans and Associates, Inc. 1716 West Marine View Drive, Suite C Everett, Washington 98201 Telephone: (425) 259-4099 By Anthony Roth PACIFIC INTERNATIONAL ENGINEERING' 310 Waterfront Building, 144 Railroad Avenue Edmonds, Washington 98020 Telephone: (425 921-1708 �125) juq --7700 July 1998 1 8 I TABLE OF CONTENTS 1. INTRODUCTION....................................................................................................... ........... 1 I . 2. STEEP SLOPE, EROSION AND GEOLOGIC.HAZARD... CONDITIONS .............................. 1 2.1 SLOPE STABILITY..........................................................................................................:. 1 2.2 EROSION HAZARD.................:......................................................................:.. 3 I 2.3 SETBACK FROM WESTERN TOP OF BANK ................ . 3 2.4 REGULATORY IMPLICATIONS...................................................................................... 3 3. WATER RESOURCES ............................. .......... 3 3.1 INTRODUCTION...............................................:................................................................ 3 3.2 METHODOLOGY...'............... .... 3 3.3 INVESTIGATION RESULTS.......................................................................................9 3.3.1 Stream ................................ ............................................................................:..............11 3.3.2 Wetland ............................ ........................................................................:..................12 I3.4 REGULATORY IMPLICATIONS....................................................................................13 3.5 PROJECT IMPACTS......................................................................................................... 13 3.5.1 Wetland Buffer............................................................................................................13 I 3.5.2 Stream...............................:..............................................:. 3.5.3 Stream Buffers................................................................:.......:....................................13 3.6 IMPACTS MITIGATION..................................................................................................14 3.6.1 Wetland Buffer............................................................................................................14 3.6.2 Stream and Stream Buffers.. ......... 14 ............................................................................... I BIBLIOGRAPHY..........................................15 APPENDIX A: Geotechnical Report APPENDIX B: Field Data Sheets LIST OF TABLES ITable 1. USFWS Plant Indicator Status........................................................................................ 9 Table 2. Wetland Functions and Values ....................................... :................................................ 10 LIST OF FIGURES Figure1. Vicinity Map.................................................................................................:......:.:........ 2 Figure 2. Water Resources Map....................................................................................... ..... 4 Figure 3. National Wetlands Inventory Map........................................................................... Figure 4. Snohomish County Stream and Wetland Atlas................................................................ 7 Figure 5. Soils Map .......:................ Critical Area Study Page i ` Sequoia Ridge Pacific Intonational Engineering 99o3s A I CRITICAL AREA STUDY I Sequoia Ridge 1. INTRODUCTION. IThe subject property is a vacant 3.70 acre site located west of and adjacent to the unopened right- of-way of 72nd Avenue West and south of North Meadowdale Road, in the Meadowdale area, in the SW'/a; of Section 5, Township 27 N, Range 4 E, W.M., Edmonds, Washington (See Figure 1). The applicant, John Thoresen, proposes to develop the site for a 4-lot short subdivision. A Critical Areas Determination performed by the City of Edmonds on January 31, 1995 found that the site contains a Wildlife Habitat and Geologically Hazardous Areas pursuant to Chapter 20.15B of the Edmonds Community Development Code (ECDC), and that the Geologically Hazardous Areas .contained two categories: Erosion Hazard Areas and Steep Slope Hazard Areas. Subsequent site evaluation and contact with City staff has revealed that the Wildlife Habitat is comprised of wooded areas and an unnamed stream and associated wetlands. The purpose of this report is to present site -specific findings of a geotechnical evaluation and an analysis of water resources. 2. STEEP SLOPE, EROSION AND GEOLOGIC HAZARD CONDITIONS Appendix A contains a preliminary geotechnical engineering report from Nelson-Couvrette & Associates, Inc. evaluating the Sequoia Ridge (John and Delaine Johnson property) from the standpoint of the stability of the steep slopes, erosion andgeologichazards. The report evaluates proposed development on the north -facing slopes of the subject property that are considered environmentally sensitive areas by the City of Edmonds sensitive areas regulations. The study found that the site was suitable for the type of development proposed, provided a setback was maintained from the top of bank along the west property boundary adjoining the Lorian Woods development. The report finds the north facing slope where development is proposed to be stable. The report references and discusses the location of the subject property within. the Meadowdale slide area and designation of the site as 3B02, a classification. identifying the. site as being underlain by material that has not failed in the past and in 25 years, has a 2 percent probability of debris slides occurring due to the steep slopes. 2.1 SLOPE STABILITY IThe geotechnical report indicates that no signs of deep-seated. instability were found on the slopes. The report further notes that soils exposed on the moderate to steep slopes are a clean sand that the geotechnical consultant would expect to be susceptible to slough types failures and Ierosion; however, the consultant concludes that this type of slope movement is typically shallow. The consultant further concludes that. the project should be compatible with the proposed development, provided that site. grading and construction are designed and implemented to maintain and/or increase the existing site stability. The consultant expects the native soils to be stable with respect to deep seated failure. Critical Area Study Page 1 Sequoia Ridge Pacific International Engineering 99o.35 rVVC/ KMA t5r�AL 1N Sao>sW ; :, N NORMA FACN < 14� N rs 14 va SOUND t FISHERl 4'IR 04 ~ � _ , �, P 3 w sw 149T4--- - tN Pl r-I � �.�W t H'�i � — 1 15 T �� `N I �' 150TH e 2 3 3 r d SP- 3;�� 152ND ST_ �� m SW �► 153RD ': _ i.• '.......:.._ �.. �._... Q 1531;D PL SW Id 156TH T. W . ( 56TH <1 ST M EA D 0 �'•� �� MEADOwoALE� =:!�: SW ti �: ::: I BEACH.:::.-:* ... . ' TQI:PARK XR57T PL SW J I 'I SW i......... �I �a d� &non- - fi= 1 TH __-. ST - 3W_ — ^ " WHARF + :D i/ TM PL SW ( SW ;I a� < i I I dl� sw PL SW 63RD ST 3 1SW 164TH ST < 3164TH I ST y� 3 = 3 3 > tst L RD � tee+ > PL wowPL • • __a.E�Y i o 3 sw • - 1,: ►�IEL� � � �68TH ST --• � A �� I � M ALE � QO �lsr v it== Z TMTH PL SW ; J > 1 Pi T �T ; W 172ND 1 ST B 1 a d MST AL1< ST 73R ~'a �SWa.173Ro yST �n' 173Np 172N 1 ST SW Z ST 9 ''� ° 7 d sw,—CU TISWI _ / all. 2 r- sr O°' �'sTti T D` XTH R .� ut 31 n 3 /7liH PL SW Figure 1. Vicinity Map Critical Area Study Sequoia Ridge Page 2 Pacific International Engineering 99o.33 I 2.2 EROSION HAZARD The Nelson-Couvrette report notes that on -site soils have moderate to high erosion potential when disturbed and exposed on slopes. The report therefore recommends that, to reduce erosion, all slopes where the soil is exposed should be compacted and re -vegetated after construction. The consultant .notes that where existing vegetation is not disturbed, erosion potential should not be significant. 2.3 SETBACK FROM WESTERN TOP OF BANK The Nelson-Couvrette report recommends that foundations for. the planned residences should be supported on the underlying medium dense or better glacial deposits and that the foundations on the hillside should have minimum 15 foot horizontal buffer between the slope surface and the outside edge of the footing. 2.4 REGULATORY IMPLICATIONS Since ECDC Section 20.15B.120.B requires a 50 foot buffer from a steep slope and ECDC Section 20.15B.090.0 requires a 15 foot building setback from any buffer, a Reasonable Use Exception under ECDC Section 20.15B.040.0 is requested from these requirements to substitute. the specific recommendations of the Nelson-Couvrette report, including allowing development on slopes, reduction of buffers with compensation and allowing elimination of buffer to west boundary slope. 3. WATER RESOURCES II 3. 1 INTRODUCTION In May 1998, Pacific International Engineering staff performed on -site investigations to Idetermine the presence, type and extent of water resources on the subject property.' The primary objectives of the site evaluation were: 1) the identification of any streams and wetlands under the jurisdiction of the U.S. Army Corps of Engineers (ACOE) and 2) the delineation of all water Iresources subject to land use review and regulation by the ECDC Section 20.15B. Approximately, 52,248 square feet (1.12 acres) of water resources were found on the subject property, generally associated with seeps along the northerly slopes down to North Meadowdale I Road and associated with the unnamed stream (See Figure 2). Representative data sheets from that evaluation are provided in Appendix B. Under Section 404 of the Clean Water Act, the ACOE has jurisdiction over the waters of the United States, including streams, lakes, ponds and wetlands. Only a 210 square foot segment of a small stream is proposed for fill. Direct contact with ACOE is not required and the City of Edmonds will be the lead regulatory agency. 3.2 METHODOLOGY Prior to conducting field evaluation, a number of sources were consulted. IAs designated in the Snohomish County Stream and Wetland Survey and Map Atlas (1989), the property lies within the Southwest Coastal watershed. This publication identifies the .thread of the stream on the subject property, but does not locate associated wetlands (Figure 3). I - Critical Area Study Page 3 Sequoia Ridge Pacific International Engineering 99o3s LEGEND ®BUFFER AREA.i298 98.SF Sl ® STREAM I = 200 BUFFER LOSS 003 ®BUFFER ADDITION) AREA-5750 SF POTENTIAL S LOSS MITIGATION O CATCH BASIN f 00 WATER VALVE - M GAS VALVE �- UTILITY POLE W t TELEPHONE CLO� o DSO ROCKERY Ifs FENCE O sAFnrARr ST:wEA f � A FIRE HYDRANT —SS— SANITARY SEWES OP— OVERHEAD f —SO— STORM DRAIN Ul —w— WATER LINE —y--�— EDGE OF ASPHA) �lan GE 1 �g0001 Ow p/�1/MI 1T.Ocl7 CV� Critical Area Study—— Sequoia Ridge J '- Page 4 Pacific InternaTSonal Engineering M.35 ;1c �v `- . ; POWH .: - �r=�.-'" :;fit• .� ��.jr, . ,; . �'.. --- -- A. 1leadowd le i [ BJ �� `� Ii "•:�=' 't' [* S COAST dry:.+!• a;e j�; } ,r P us ji -RigsBay L'aTlO T .Y es 417 ioui �� . /�; mil`. j ♦ '.f i _ \. - ��:{; •' � �. I 1 • 1. �� 'i � ` �_ �i� � � i =->- • it . 2•+¢"•� . ` . • \\ ..-.-----�--i -ram FIGURE 3. NATIONAL WETLANDS INVENTORY MAP SCALE: 1":2000', FROM USFWS NWI EDMONDS EAST QUADRANGLE Critical Area Study Page 5 SequoiaRidge Pacific International Engineering 990.35 The National Wetland Inventory (NWI) has evaluated wetlands throughout the Edmonds East USGS quadrangle, using the system described in Classification of Wetlands and Deepwater Habitats of the United States (Cowardin 1979). The NWI map indicates no occurrence of wetlands on the site (Figure 4). I Soils on the site have been mapped as Alderwood gravelly sandy loam and Everett gravelly sandy loam series by the USDA Soil Conservation Service and appear in the 1983 Soil Survey of Snohomish County (Figure 5). To perform the wetland delineation for the site, the 1997 Washington State Wetlands Identification and Delineation Manual (Ecology 1997) was used. The methodology. in this manual recognizes that the three parameters of hydrology and wetland plants are generally found in wetlands and that these parameters are important in the establishment and maintenance of wetland communities. Within the methodology, indicators are evaluated in the field to determine satisfaction of each of the three parameters for establishment of wetland boundaries: 1. Hydrophytic Plants - The US Fish and Wildlife Service (Reed, 1988 and 1993) has established a rating system which has been applied to commonly occurring plant species on the basis of their frequency of occurrence in wetlands. Species indicator status expresses the range that plants may occur in wetlands and non -wetlands (uplands). Within the State and federal methodology, satisfaction of the hydrophytic. plant community criterion is satisfied when the plant community is comprised of 50 percent or more of the dominant species which are adapted to or tolerant of saturated soil conditions: an indicator status of facultative (FAC), facultative wetland (FACW) or obligate (OBL) wetland (Table 1). Modifiers are used with the Facultative Indicator categories to more specifically define the frequency of occurrence. A positive (+) sign indicates plants are more frequently found in wetlands than the category indicates, whereas a negative (-) sign indicates plants are less frequently found in wetlands than the indicator signifies. A status of FAC-. does not meet the hydrophytic plant community criterion. 2. Hydrology - Evidence of permanent or periodic inundation, or (at least) soil saturation to within 12 inches of the surface for one week or more during the growing season I (soil temperatures above 41°F); indicators other than standing water or soil saturation include stained leaves, soil surficial cracking or water-bome litter. 3. Hydric soils - Soils that are saturated, flooded, or ponded enough during the growing season to develop anaerobic conditions in the upper soil horizons, or to the depth of 12 to 18 inches; indicators include high organic content, low soil chroma (Munselll matrix chroma of 2 with mottles or less than 2 without mottles) or gleying. Munsell Soil Color Charts, Kollmorgan Instruments Corporation, Baltimore, Maryland Critical Area Study Page 6 Sequoia Ridge Pacific International Engineering 99o35 AN .44 't.iY'•e ♦ r • .�a. �_ t '�rii!Sys•.^mow • � . .@!' " � ✓ vale•, s _„�; tiO�e,.r � •. .raj fr f. a�.M, �+• :•a• t::. �.:.3n Noy • � ti:J�' - �V �` �"�'' '.(.'/ Ift .a : � a.t;�c '', � t�a♦ 4� -• t •' r.j. Jam`%; .,' ^!� �'•, .[!� 1''.. �: •/� ter` ter'' .,, � "` • � � J G i •. ��' JV'••.• ra � ��a 7v �' w n FIGURE 5. SOILS MAP SCALE: 1 ":2000', FROM USDA SOIL SURVEY OF SNOHOMISH COUNTY 2,4: Alderwood gravelly sandy loam 17: Everett gravelly sandy loam Critical Area Studv Page 8 Sequoia Ridge Pacific Intemational Engineering 99o.35 ITable 1. USFWS Plant Indicator Status Indicator Plant Indicator Status I Status Category Abbrev'n Definition (Probability of Occurrence) OBLIGATE UPLAND UPL Occur rarely in wetlands (less than 99 percent) and I almost always in uplands (greater than 99 percent) FACULTATIVE FACU Occur sometimes in wetlands (1 to <33 percent), but UPLAND more likely in uplands (>67 to 99 percent) FACULTATIVE FAC Equal likelihood in u lands and wetlands 33 to 67 q P ( percent) FACULTATIVE FACW Occur sometimes in uplands (1 to <33 percent), but WETLAND more likely in wetlands (>67 to 99 percent) . OBLIGATE WETLAND OBL NOT LISTED NL Occur rarely in uplands (less than 99 percent) and almost always in wetlands (greater than 99 percent) Not listed in USFWS National List of Plant Species that Occur in Wetlands For the analysis of this site, the presence of dominant hydrophytic vegetation was used for the principal delineator of the boundary between wetland and upland areas, supplemented on a case - by -case basis with organic content or soil color evaluation to verify presence of hydric soils and in the absence of a positive indicator of wetland hydrology, use of professional judgement. At several locations which supported uniform or homogeneous plant cover within the delineated I wetland areas, sample plots were established for recording of wetland characteristics and for an assessment of wetland functions, including those described in Table 2. 3.3 INVESTIGATION RESULTS Site visits were conducted on May 27 and 28, 1998 to determine the presence, type and extent of critical areas (wetlands and streams) on the subject property. Sample plots were established in areas of homogeneous vegetation within the areas evaluated. For each habitat type, the dominant vegetation (in addition to the common and infrequently -occurring species) was recorded for each vegetation layer and the soil type/soil color and depth of soil saturation recorded (See Appendix B). s - Critical Area Study Page 9 Sequoia Ridge Pacific Intonational Engineering 99o.33 I Wetland Function hydrologic support Table 2. Wetland Functions and Values Definition Highest Value Lowest Value provision of water for biological productivity and groundwater permanently saturated or inundated systems temporarily recharge inundated or saturated hydrologically isolated depressions streambase flow contribution potential the wetland's potential and ability to contribute to stream base location in the upper segment of the basin and low and ability flow based on its location within the basin and its surface water recharge rate gt either of the following: connected connection with a stream wetland or with permanent outlet to stream and one of the following: permanently flooded, outflow greater than inflow or topography favoring discharge shoreline stabilization presence of wetland plants along the stream shoreline in a� Woody vegetation at least 200 yards in width configuration which serves to dissipate periodic increased flow or current water quality improvement, including toxicant retention is related to soil type; sediment retention and sediment and toxicant retention, nutrient nutrient uptake/conversion are related to presence of macrophytes uptake or conversion and pollution in the subject waters for bioftltration; pollution reduction is reduction related to the opportunity for pollutant inflow to the wetland storm/floodwater management groundwater recharge wildlife habitat and biological functions based on the location and of the wetland within the basin and the wetland's physical features variables include periodicity and rate of flow, wetland size and depth, surface topography and underlying soils and geology based on habitat characteristics and biological process values, including: habitat type, diversity, size and value within wetlands and adjacent uplands; food quality and diversity; biological community diversity and structure; plant productivity and support for and presence of game; commercially important or unique species; and opportunities for refuge and provision of surrounding vegetation with potential to reduce visual and noise disturbance organic soils = toxicant retention; areas of reduced water velocity containing vigorous plant growth = sediment retention and nutrient uptake/conversion; point or non -point sources of pollution = pollutant removal opportunity wetland with impermeable or slowly permeable soils comprising e5 percent of the upslope watershed and either no permanent outlet or constricted outlet with unconstricted inlet or evidence of floodplain or expansive flooding within one year; wetland of more than ten acres year-round, open water wetlands greater in size than 10 acres with water depths greater than 10 feet high community diversity, valuable species support, can provide relatively equal proportions of open water and vegetative cover and have refuge potential located in the lower basin and either high recharge rate, without permanent outlet or not connected to a stream submergent vegetation less than 10040' yards wide fast -flowing streambed composed of mineral soils, with minimal plant growth and no pollutant inputs less than 5 acres small, topographic low areas which are only seasonally inundated absence of or limited manifestation of community diversity, valuable sped support, relatively equal proportions o open water and vegetative cover and refuge potential Critical Area Study Page 10 Sequoia Ridge Pacific International Engineering 990.35 The on -site water resource is a 1.12 acre mixed palustrine and riverine forested, scrub -shrub and emergent wetland and unnamed stream, generally located .south of North Meadowdale Road, along and at the toe of steep northerly -trending slopes, with some influences from seeps flowing out of the slopes. Although the site's water resources are directly associated, since the City of Edmonds regulates wetlands and streams differentially, the wetland and stream components will be described separately. - 3.3.1 Stream The unnamed stream enters the site from the east, where flows are supported by a stormwater outfall within . the unopened right of way of 72"d AvenueWest West and seeps. Flowing through an man-made, incised channel at the northwestern corner of the site and immediately south of North Meadowdale Road, the stream terminates, as it discharges into -a catchbasin, and flows into a culvert under the right-of-way of North Meadowdale Road (see Figure 2). Ultimate discharge is to Brown's Bay (Puget Sound). Data Plot No. 6 (See Appendix B) is representative of site streamside conditions. Understory wetland vegetation within the margins of the stream includes lady -fern (Athyrium filix-femina, FAC+), salmonberry (Rubus spectabilis, FAC+), piggy -back plant (Tolmeia menziesii, FAC), skunk cabbage (Lysichiton americanum, OBL) and field horsetail (Equisetum arvense, FAC). In addition to these species, portions of the stream bank and higher areas in the midst of the stream contain sword fern (Polysticum munitum, FACU) and stinging nettle (Urtica dioica, FAC+), as well as red alder (Alnus rubra, FAC). Upland understory vegetation is deerfem (Blechnum spicant, FAC+), salal (Gaultheria shallon pursh., FACU), red huckelberry (Vaccinium parvifolium, FACU), red elderberry (Sambucus racemosa, FACU), Himalayan blackberry (Rubus discolor, FACU) and thimbleberry (Rubus parviflorus, FAC-). Red alder and western hemlock (Tsuga heterophylla, FACU-) form the upland overstory vegetation. In general, the where the stream flows through site areas of relatively gentle topography (see Lots 2 and 3, Figure 2), the streambed widens, velocities slow and sediments are typically very dark gray (IOYR 3/1) silt loam. Predominantly in response to placement of fill adjacent during the construction of North Meadowdale Road, the stream narrows in Lot 4, where the main flows .narrow to widths of three feet or less and rate of flow increases in the deeply incised and man- made channel in the northwest corner of the site. In this channel, and in response to the flashy nature of flows here, the. streambed is comprised of sorted gravels over grayish brown (IOYR 5/2) gravelly silt loam. No fish were noted during site visits in late May 1998. The silt loam streambed in the Lots 2 and 3 do not provide good fish rearing habitat. The markedly increased velocities in the narrow channel in Lot 4 decrease the fish habitat value where substrates would otherwise support fish use. Downstream barriers to fish passage have further eliminated the potential that anadromous fish -rearing (e.g., salmon and sea -run cutthroat trout) could take place on site. The stream receives hydrologic support from seeps and from a storm drainage outfall and the hydrologic function of the stream is principally in groundwater and surface water reception and discharge; due to the perennial nature of the stream, this function is considered moderate. Wider Critical Area Study Sequoia Ridge Page 11 Pacific Intemational Engineering 99om areas of the stream provide limited function in floodwater attenuation and desynchronization functions, as well as some retention of sediments and nutrients. While not significantly greater than the adjacent uplands, biologic functions include moderate primary productivity and food chain support, as well as bird habitat and sanctuary and refuge. The stream corridor provides moderate habitat functions for invertebrates and amphibians. Barriers to fish passage and lack of quality streambed habitat have eliminated fisheries functions. Socioeconomic functions are aesthetic in nature and are judged to be moderate. 3.3.2 Wetland Within the area of direct hydrologic support from the stream, wetlands are classified by Cowardin (1979) as riverine forested, scrub -shrub and emergent. On the slopes outside of the stream corridor, and hydrogically supported by seeps, wetlands are classified as palustrine forested and scrub -shrub. Due to the general absence of standing water in the sloping areas, emergent wetlands are an insignificant component. Supported by data plots: 26 and 41 (Appendix A), the shrub component of understory wetland vegetation is dominated by salmonberry, with devil's -club (Oplopanax horridus, FAC+) interspersed in some steeper areas where saturation further from the surface. The herb layer is generally dominated by piggy -back plant, with lady -fern, skunk cabbage, field horsetail and stinging nettle as lesser constituents. The wetland overstory is comprised of red alder. In some locations with slight elevation and in adjacent uplands, sword fern (Polysticum munitum, FACU) is found. The wetland vegetation criterion is satisfied. Where a mosaic of higher areas occur within the wetlands, vegetation trends to upland vegetation. For delineation purposes, such higher areas were included within the boundaries of the wetlands. Upland overstory is dominated by red alder, with big -leaf maple (Acer macrophyllum, FACU) as a lesser constituent. Shrub vegetation is dominated by salmonberry, with red elderberry, indian plum (Oemlaria cerasiformis, FACU) and thimbleberry. Herb vegetation is dominated by swordfern. Surface soils to a depth in excess of 16 inches at data plots 26 and 41 are very dark gray (I OYR 3/1) black silt loam and sandy loam. This soil color, along with other indicators, such as clear. presence of an aquic moisture regime, satisfies the hydric soil criterion. A data plot on the slope immediately adjacent to a seep (DP 26X, Appendix A) displays non-hydric soils: dark grayish brown (1 OYR 4/2) sandy loam and brown (1 OYR 5/3) loamy sand. As noted above, hydrologic support for the wetlands on the sloping areas is from surfacing groundwater in seeps, while wetland areas adjacent to the stream are supported by stream flows. and surface water via the adjacent ditch. At the time of sampling, depth of saturation was from 0 to 8 inches below the surface. The hydrology criterion is satisfied. The wetlands on the site provide hydrologic functions such as flood storage, recharge and discharge and. some water quality improvement (in stream -associated wetlands due to their Critical Area Study Page 12 Sequoia Ridge Pacific International Engineering m.35 ' location downstream from impervious surfaces subject to vehicular use). These functions are limited by position in the watershed as well as occurrence in sloping areas; the latter is due largely to. Groundwater recharge is limited due to •underlying hardpan. Biologic and habitat Ifunctions are similar to the stream corridor and not significantly different in value from functions of the adjacent uplands. 3.4 REGULATORY IMPLICATIONS Section 20.15B.070 of the- Edmonds Community Development Code (ECDC) -classifies streams and wetlands as critical areas. ECDC 20.15B.070.4b classifies the on -site stream as, a Category 2 stream. The stream is subject to 25 foot buffers from the top -of -bank under ECDC 20.15B.090 B and 20.15B.130.G. Based on size, presence of two or more wetland classes (including a ' forested class), ECDC 20.15B.070.5b rates the on -site wetlands as Category 2. Under ECDC 20.15B.090 B and 20.15B.140.C, 50 foot buffers are required. ECDC Section 20.15B.090.0 requires a.15 foot building setback from any buffer. ' Since the unnamed stream on the site has mean annual flows of less than 5 cubic feet per second (cfs), a Clean Water Act Section 404 Nationwide Permit 26 applies to the fill identified in ISection 3.5.2 below and direct notification to the ACOE is not required. 3.5 PROJECT IMPACTS The short subdivision has been designed to minimize impacts to on -site, regulated . water resources and their buffers. Since the regulatory requirements regarding topography and critical area pose a hardship for development of this site, Reasonable Use Exception under ECDC Section 20.15B.040.0 is requested to reduce wetland buffers with compensation. Beyond those described below, no impacts to regulated wetlands or their buffers are proposed. 3.5.1 Wetland Buffer The project seeks a site -specific reduction of a portion of the southwesterly wetland buffer within proposed Lots 2 and 3 (see Figure 2). In the area of reduction, buffer less than 50 feet, but greater than or equal to 25 feet will be maintained; the area of buffer reduction is approximately 2,300 square feet. 3.5.2 Stream A driveway is proposed to provide for access to Lot 4 see Figure 2). Driveway construction will result in placement, within the stream, of a culvert of sufficient size to maintain hydrologic capacity of that stream section. Fill for the stream crossing will result .in the loss of Iapproximately 210 square feet of in -stream habitat. 3.5.3 Stream Buffers IAs portrayed in Figure 2, construction of the driveway will result in the loss of stream buffer on either side of the stream totaling approximately 800 square feet. I Critical Area Study Page 13 g Sequoia Ridge Pacific International Engineering 99o.3s I 3.6 IMPACTS MITIGATION For preliminary approval, the following sections outline a conceptual approach in compensation of unavoidable impacts to critical areas on the site through either retention of addition areas of equal functions and values or through creation of replacement with water resources of equal or better function and value. Upon concept approval and during preparation of final engineering documents, a final mitigation plan will be prepared which identifies goals and objectives and specifies details of construction of created mitigation areas, including grades, substrates, plant materials and specifications for installation, construction management and protection measures for adjacent critical areas during construction, plus a plan for three-year post -construction monitoring and a contingency plan. Since such a final mitigation plan should be considered schematic in nature and actual field conditions might require adjustment in planting in response to actual conditions, a qualified biologist should be consulted prior to implementing the future mitigation. Following construction, a site visit should be coordinated with the project biologist for review of post - construction. conditions by City of Edmonds staff to ensure that goals and objectives established in the final plan, as well as conditions of approval, have been met. 3.6.1 Wetland Buffer As compensation for approximately 2,300 square feet of buffer reduction, the applicant proposes to retain approximately 5,750 square feet of additional buffer throughout the proposed lots. The limits of the buffers will be contained within an easement area on each lot and no future development will occur in such areas. 3.6.2 Stream and Stream Buffers As compensation for a loss of stream habitat and associated buffer habitat totaling approximately 1,100 square feet, the applicant proposes to widen the stream corridor as shown conceptually in Figure 2 and create additional stream habitat in the amount of approximately1,730 square feet. A substratum of gravels and finer materials will be established and native, non-invasive plantings will be installed to encourage establishment of habitat similar to that of adjacent areas. Following construction of driveway access to Lot 4, any disturbed areas outside the limits of the driveway)will be replanted with native, non-invasive trees and shrubs consistent with those found in the adjacent buffer. Critical Area Study Sequoia Ridge Page 14 Pacific International Engineering 99o.3s BIBLIOGRAPHY Catalog of Washington Streams, Volume 1', Washington Department of Fisheries, 1975. Cowardin, L.M., V. Carter, F.C. Golet and E.T. LaRoe. 1979. Classification of wetlands and deepwater habitats of the United States. Office of Biological Services, Fish and Wildlife Service, U.S. Dept. of the Interior, FWS/OBS-79/31. Reed, P. B., Jr. 1988. National list of plant species that occur in wetlands: Northwest (Region 9). U.S. Fish Wildl. Serv. Biol. Rep. 88(26.9). et al. 1993. 1993 Supplement to List of Plant Species that Occur in Wetlands: Northwest (Region 9). U.S. Dept. Interior Fish Wildl. Serv. December 1993 Snohomish County Department of Public Works. - 1987. Aquatic Resources of Snohomish County, Volume I: Stream and Wetlands Survey Map Atlas. Snohomish County Department of Public Works and Planning Division, Department of Planning and Community Development. January, 1987. United States Department of Agriculture, Soil Conservation Service. 1983. Soil Survey of Snohomish County, Washington. Prepared in cooperation with the Washington IAgricultural Experiment Station. United States Department of the Interior, Fish and Wildlife Service. 1987. National Wetland IInventory, Edmonds East Quadrangle, Washington. Prepared for the Office of Biological Services for the National Wetland Inventory. Washington State Department of Ecology. 1997. Washington State Wetlands Identification and Delineation Manual. Publication No. 96-94. March 1997 Critical Area Study Sequoia Ridge Page 15 Pacific Intemational Engineering 99o.3s APPENDIX A GEOTECBMCAL REPORT NELSON-COUVIRETTE & ASSOCIATES, INC. CONSULTING GIFOTECHNICAL ENGINEERS, GEOLOGISTS AND ENVIRONMENTAL SCIEN77STS I 17311.135th Ave. NE, A-500 Snohornlah County (MM 7941392 Woodinville, WA 98M (208) 48&1889 • FAX 481.2510 Wenatchee/Chelan (509) 784.2756 Mauch 29, 1995 - Mr. Jain Jobnson 16122 - 72nd Avenue West Edmonds, Washington 99026-4517 Preliminary Geotechnical Engineering Report Residential Development Edmonds, Washington NCA File No. 145995 Dear Mr. Johnson: I0111I s 111194M (ON I This report presents the results of our prelin inary geotechnical evaluation for the portion of your property to be potentially developed. The site is located at 16122 - 72nd Avenue West, in the City of Edmonds, as shown on the Site Vicinity Map in Figure 1. You have requested that we prepare a preliminary geotechnical report to evaluate the site for development of potential residential housing. Mr. Jim Miller, of Lovell-Sauerlavd & Associates, Inc., has provided us with a site plan titled "Meadowdale Heights PRD Preliminary Grading Plan," dated March 9, 1995 by Lovell-Saiucrland & Associates, Inc., showing the proposed site layout for the project. You desire an evaluation: of slope stability and gea=W earthwork parameters. We have been informed that at this time a reconnaissance report evaluating development potential of the Property is desired. Additional work may be require regarding specific sensitive aro issues, Prior to platting. That additional work is beyond the scope of this report. The site slopes moderately to steeply down towards North Meadowdale Road. The site layout provided to us indicates that potentially seven buildings, almg with a new access .road, are proposed for construction along the upper portion of the slope and the knob at the west end of the site. Based on the plan provided,. it appears that up to an 11 foot cut would need to be made for the access roadway. The residences may incorporate daylight baseizients into their design. Prel' Geotechni�cal t��y �m8 Report Residential Development - Edmonds March 28, 1995 NCA File No. 145995 Page 3 The slope a vegetated with medium to large diameter trees along with thick underbrush of ferns and blackberry bushes. We observed two fallen trees and a few trees with slightly bowed trunks. However, the majority of the trees were straight. There is a series of trails on the slope, wbaich in places have been cart into the hillside. Light brown medium sand was observed in these cut areas. Portions of the slope arc covered with landscaping debris such as branches and cut trees. B appeared that so = vegetation bad been pushed over the top of the slope and/or was cut and leg an the slope when the trails were created. We did not observe obvious areas of fill. The lower wetland area is overgrown with blackberry bushes, brush and scattered trees. There was standing water in the drainage draw at!the time of our visit. Geology The Prelimiructy Surfigial Geologic Map of the Edmonds Fast and Edmonds West 01radrangle& Snohamisb and King .Counties: Washinonj by Mackey Smith (Washington Department of Natural Resoirrees, 1975) was referenced for mfnmation about the area geology. Tins map delineates the soils in the vicinity of the site as Esperanee Sand (Qe) overlying the Whidbey Formation (Qw). An area defined as Old I.andsh (Qols) is mapped to the west We reviewed the City of Edmonds critical areas ordinance (No: 2974) and have reviewed the associated reports by Gooftgmeers, Inc. and Rodger Lowe & Associates, Inc. with regard to the Ma dowdale Slide area. This site is mapped as being associated with the Meadowdale slide complex. It is classified as a 3B02 area This classification identifies the site as being underlain by material that has not failed m the J past, and has a 2 percent probability of debris slides occurring due. to the steep slopes, in 25 years. Tba its classified as Whidbey consist of well sorted beds -of clay, silt or sand. The Esperanee is a unit within tine advance outwash which is generally a medium to coarse sand with trace amounts of fines and varying gavel content. 'The Fsperance sand contains a low:poventW of fine grain particles- It has moderate to high strengths when confined. However, in sloping areas the outer portions can become loose. Advance outwash was deposited at the base of advancing glaciers. The Whidbey and Esperance, therefore, have been overridden by past urtrusion of continental glaciation.: The last period of glaciation, the Vashon Stade, ended approadmateiy 11,000 to 13,000 years ago. Durirsg the Vashon Stade, the Puget Sound region was overridden by over 3,000 feet of ice. Soil layers overridden by dw ice sheet were compacted to a much greater extent than those that were not. NELSON-COWRETTE & ASSOCIATES, INC. Preliminary Geotechnical Engu eemg Report Residential Development - Edmunds ! Mamb 28, 1995 NCA File No. 145995 Page 5 with beat trunks at the base. This is usually an indication that some surface soil creep is occurring: The soils exposed an the moderate to steep slopes. are a clean sand that we .would expect to be susceptible to slough type faiilures and erosion. 'rids type of slope movement is typically shallow. CONCLUSIONS AND RECOMMENDATIONS General The project site should be compatible with the proposed development, providing that site grading and construction are designed and implemented to maintain and/or increase the existing site stability. We expect that the density of the surficial sands will increase with depth, but this should be evaluated prior to construction. The native soils are expected to be stable with respect to deep seated failures. The upper soils are weathered and less dense and should be considered near their natural angle of repose on the slope five. Once disturbed, these soils have a moderate to high degree of erosion. We recommend tbat erosion on these slopes be controlled. This is discussed in the Erosion sub -section. We would expect sloughing type failures from cuts m the upper loose to medium dense soils. The site is mapped as being a part of the Meadowdale slide complex that has not moved in the recent past. It is mapped as having a small potential for debris slide type movements or sloughing events. It is. our opinion that if proper drainage and erosion control measures are taken, the potential development should have a minimal impact on the stability of the slopes on the site. Our specific recommendations are presented in the Erosion and Drainage sub -sections. Foundations for the planned residences should be supported on the underlying medium dense or better glacial deposits. The foundations on the hillside should have a minimum 15 foot horizontal buffer between the slope surface and the outside edge of the footing. This may be accomplished by extending the footings below grade. it is possible that this buffer could be reduced after review of site specific conditions. Based on the preliminary grading plan provided, it appears that a cut up to 11 feet high will be made for the access roadway and the buildings may incorporate a daylight basement into their design. The road cut will require some type of retaining structure. Based on the soil conditions encountered we do not recommend the use of rockeries greater than 4 feet in height unless specifically designed as a retaining suuctu e. Types of retaining structures applicable for this site are concrete retaining walls or a gravity retaining structure such as a reinforced earth fill. A reinforced soil wall is constructed with reinforcing geogrid or geotextiles placed in the compacted ball. 7U reinforcing typically extends 50 to 80 percent of the wall height back f um the wall firce. These walls n xpire a facing such as rockeries or concrete blocks on the exterior NELSON-COUVRETi►>E & ASSOCIATES, INC. Preliminary Geotochnical Engineering Report Residential Development - Edmonds March 28, 1995 - NCA File No. 145995 Page 8 • Standing water, water loosened soils and slough should be removed fran the foundation excavation prior to Ping coamte, For foundations constructed as outlined above and founded on as undisturbed native soil, we reconitneiid an allowable design bearing pressure of 2,000 pounds per square Soot (ps fl to be used for the footing design. Tine foundation bearing soil should be.evaluated by a representative of our firm. The Puget Sound region is classified as a Zone 3 by the Uniform Building Code. A one-third increase in the above allowable bearing pressure may be used when considering short-term transitory wind or seismic loads. Drainage The finished ground surface should be. graded such that storm water is collected and directed off the site. Concentrated water run-off should not be allowed to discharge onto the slopes. Final site grades should allow for drainage away from the building. We suggest the finish ground be sloped at a gradient of 3 percent minimum for a distance of at least 10 feet away frorn the building, except in the area that are to be paved Storm water should not be drained onto the sloped areas of the site. Surface water should be collected by permanent catch basins and drain lines and be discharged into a storm drain system. Perimeter footing drains should be installed at the base of all perimeter footings. Subsurface walls should' be provided with wall drainage systems. Roof drains should not be emnected to perimeter footing drain or wall drain systems. USE OF THIS REPORT AND WARRANTY We have prepared this report for Mr. John Johnson and his agents, for use in Prelitninary planning and design of this project. The data and report should be provided to the contractor for their estimating purposes, but our report, conclusions and interpretations should not be construed as a warranty of subgrade I conditions. The purpose of this report is to provide preliminary, general reconinwadatims for site development. Our work was based on a limited number of shallow explorations, sand our recommendations should act be considered adequate for final design. It is likely that additional explorations and geotechnical evaluation will be required as development plans proceed The scope of our work does not include services related to construction safety precautions, and our recommendations are not intended to direct the contractors' methods, techniques, sequences or procedures, NELSON-COUVRETTE & ASSOCIATES, INC. Preliminary Gleotechnical Engineering Report Itesrrdendal Development.- Edmonds March 28, 1995 NCA File No. 145995 Page 9 cwcpt as specifically described in our report for consideration in design. Them are possible variations m sabsurbae conditions. We recommend that project planning include contiagcmies in budget and schedule, should areas be found with conditions that vary f m those described in this report. IWithin the limitations of scope, scbedulc and budget for our services, we have strived to take care that our work has been done in axordauce with generally accepted practices followed w this area at the tune this Ireport was Prepared. No other conditions, expressed or implied, should be understood. We appreciate the opportunity to be of service to you. If there are any questions concerning this report or if we can provide additional services, please call. Sincerely, NELSON-COUVRETTE & ASSOCIATES, INC. William B. Beuzer Project Engineer r:XPIREs (64-1- Qb EXPIRES William M. ICuciS PE Charles P. Couvrette, PE Senior Engineer : Principal Engineer t Three Copies Submitted Four Figures cc: Mr. Jim Miller - Lovell-Sauerlaad & Associates, Inc. NELSON-COUVRETTF & ASSOC/A7ES, INC. 1 ZZ,` f —: -• r `♦ r i' f r I Y 1 \1�7 J 1t /! t' I `\ 1 1 t r UMTC '•�� i•':' it • , • ' �; � +ri.. / / ,!�•/•, r , r \ UNITS t • I' ' • I / / ' I / r/r •� --_ t -r ��' 10 11> UNITA \� ` t I ! Irl f f r / �' 'r rm I f r I HA-3jo ' UNITE / / /// r / , .. UNIT F / rrr / r / � f� I / / ,' r •> r Z I t / r ti i ram, 10 rHA- / 'r JNIT G LEGEND ' ' r r' r' r/ r< / / r' r f I 1 I �►; . .' NUMBER AND APPROXIMATE LOCATION OF HAND AUGERS K UNIT A LETTERING SYSTEM BY NCA FOR DESCRIPTIVE PURPOSES s / PROPOSED 72nd AVENUE WEST TE PLAN CREATED FROM UNTITLED AND UNDATED PLAN ROVIDED TO US BY LO'VELL-SAUERLAND dr ASSOCIATES, INC. o so too JOHNSON FIOURE NEc oN-CowRsrre a AssociatEs,lNc. Z tbuuiere 6tonerMeu ttMttwtay. woleoirrf sorts 1• - So' �"0F""�0`""�'�` `'�`� FILE NO. 145995 DATE MARCH 1995 f- • • DEPTH USC LOG OF EXPLORATION SOIL DESCRIPTION III HAND AUGER ONE ( u 0.0 - 0.4 BRANCHES, STICKS AND DUFF (VERY LOOSE, MOIST) 0.4-1.7 SP-SM BROWN FINE TO MEDIUM SAND WITH SILT,' TRACE ROOTS AND GRAVEL (LOOSE TO,MEDIUM DENSE, MOIST) 1.7-2.3 SP BROWN MEDIUM SAND WITH GRAVEL, SCATTERED COBBLES AND TRACE SILT (LOOSE TO MEDIUM DENS- MOIST) (Qe) SAMPLES WERE COLLECTED AT 1.2 -1.T AND 1.9 - 2.3 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 2.3 FEET ON 3MM ` HAND AUGER TWO 0.0-20 SP LIGHT- BROWN MEDIUM SAND WITH TRACE SILT AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) 20 - 3.5 SP TAN -GRAY MEDIUM SAND WITH TRACE SILT (MEDIUM DENSE. MOIST) (0e) SAMPLES WERE COLLECTED AT 1.1-1.8 AND Z6-3.2.FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED I HAND AUGER WAS COMPLETED AT 3.5 FEET ON SIM HAND AUGER THREE 0.0-2.0 SP LIGHT BROWN MEDIUM SAND WITH TRACE GRAVEL AND SILT (LOOSE, DAMP TO MOIST) 2.0-&0 SP TAN -GRAY MEDIUM SAND WITH TRACE GRAVEL AND SILT (LOOSE TO MEDIUM DENSE GRADES TO MEDIUM DENSE. MOIST) (Qe) SAMPLES WERE COLLECTED AT 1.5 - 20 AND 2.5 - 2.9 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED 1 HAND AUGER WAS COMPLETED AT 3.0 FEET ON W&W HAND ALIGER FOUR 0.0 - 0.2 DUFF 0.2-0.6 SP LIGHT BROWN MEDIUM SANG WITH TRACE SILT (VERY LOOSE. DRY TO MOIST) (SLOPE WASH) Q8 -12 ML DARK BROWN TO BLACK ORGANIC SANDY SILT (SOFT, DAMP TO MOIST) (BURIED TOPSOIL) 1.2-4.5 SP LIGHT -BROWN MEDIUM SAND WITH TRACE GRAVEL AND SILT (LOOSE TO MEDIUM DENSE GRADES TO MEDIUM DENSE.. MOIST) (ae) SAMPLES WERE COLLECTED AT 0.6 -1.0 AND 4.0 - 4.5 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 4.5 FEET ON 34M . HAND AUGER FIVE 0.0 - 0.6 DUFF 0.6 - 2.5 SM LIGHT GRAY RUST BROWN MOTTLED SILTY FINE TO MEDIUM SAND WITH GRAVEL AND SCATTERED COBBLES (MEDIUM DENSE, MOIST) (Qe) SAMPLES WERE COLLECTED iT 13 -1.8 AND 20 - 24 FEET GROUND WATER WAS NOT ENCOUNTERED. HAND AUGER WAS COMPLETED AT 2S FEET ON 3f M INELSON-COUVRETTE S ASSOCIATES, INC FILE NO.145M FIGURE 4 • N f APPENDIX B DATA SHEETS m PIE WETLAND DELINEATION DATA FORM rPlot No. b ROUTINE•0 ITE DETERMINATION METHOD Transact ID Weather, w• Cowards ProjwVSite: -•'jo.%uAte. V,%AfteDate: Field Investiga o M MB . Size(ac): <0.5 <1 •1.2 - 5 Nommd Conds? Dtshxbance? Y Problem Area? Y Cover class 1- 0.54 2.5 2-5 • 2S♦ 15 d- 2S - 37.5 4- 50.75482. 7t{ • 95465 a. 3.954 97.5 WA. DomhaM Pbm Spp CW CM kblml« stew Sheum WA P C- oomkwM CM k11oM8 Stream sm. ATE FAG+ LS�lgs}I S VAQA SRW► 2. G AI v AI.RV FAG O rLV np O bwM WA. _- — O pAy�h •pr �d•o1 O momA •otter a t.d. r nw.....H materra.ywwriw lvv n@m*jM@lm * 1n0UN.:Q1We llyacom prp®N R@ft*": 0>50% 0<50%l0el, FACW of (no FAC-)) O o0w -` MWW?&N S«I M20 OWN • S•rlr (a• M pnd ��N C•plh a hoe H2O in pMmft. V Oaw P MftoMton: 1j1;'y %W n4ft ]S.dM14r• O seat n«M d•po•11 O WA. dreYrae poWns . saw a•td evlerwe d •uAMOe M�.+�Nwn «eo+ e.hr.Ma, SeoandW lm4mkm•: O oxktmd rod d,-- wWlr O wat«•eened Meese O bW Mot"L, dwt (3FAC•Naftl Tat (In mp a hydrol) O oaw Reo«fsf 0218: O skean- bke Of lift 91N9e O Model photo O ol?w O nWw Orowkq 8eawn? ft Meed omWdmft O aEey prprM o aN Irnp a 1a.r "l-F o 1NMbr1d hydrNo9y? N RMMonMlr. aos s to N NMN ta- melftoolor,_ olor t OW ��" CaMkm klpp r N 0-110 b � y N Y® 5` �YN YN VN 'bsbw A h«Q� YN It,"b00O etlAo Odor O ApbYge�•rPA&x oondlbrr Oote0 Illpt swum orprk Comm M send, ode O co meftne O avMb atrMMktn9 kt sane, soft Fl"ft soft lit OL"d 011m hys+e not MseNgM DIFTl11MIATION Ara IIATMAil Waard?Fhmb. as no rs0 no soft no h)*W 8Mn•pb psis whin .� . a, FUNCTIONS AND VALUES HYDROLOGIC SUPPORT Groundwater recharge ( L WAl Groundwater dlecharpe HfA l ' Stream besefbw oontriWAl Floodwater attenuation (H Floodwater detention (H MI Floodwater retention (H M Floodwater attenuation (H .. • rtowwawraesyrlcrlrorllzatloR (H f"A) WATER OUALITY FUNCTIONS Sedlment/ahorellne stabilization (H AL Retention of sediments. nutrients or ImZritsi H IKI. AL__, Transformation of nutrients or toxicants (H Wastewater treatment (H M L A NATURAL BIOLOGICALIbNr- Pd=fY WoducllviN (H Organic accurn(VI AI Urn Organic H L WAA1 1 ulatik Decomposltim (H N/AI Detrital transport (H WA Food cflaln support LL WNutrient cycling lion (H L AI WA1 HABITAT FUNCTIONS Invertebrates (H L WA) • AmphUwls (H N/A) • Fishedes (H M W l Sam %9q and re" (H WAl SOCIOECONOMIC FUNCTIONS Nowconsurnplive value Rect"donef (H M,L NIA)Aesthetic (HAMNL HtoW isrlpl (H L (M • Consumptiveval Flstlerlas (H M. I.Rerwwable rssou H M L Al AWIc ldxal (H M L Wflate •fn/1 n Data Plot location Sketch • 91 r 0 PIE WETLAND DELINEATION DATA FORM Plot No. Z�L ROUTINE ON§jTE DETERMINATION METHOD Transact ID Weather. Cowardin Project/Site: r Date: Field Investig n M MB Size(ac): <0.5 <1 I -2 :5 Normal Condo? an Disturbce? Problem Area? Y cow Cis" 1■ 0 • si 2.5 2-5.25415 ,- 25 - W437.5 a 50. 75♦412.575 • os♦!S tl. >9s-11 97.5 W& DomhrM PWA Sm Cvr CM h oodor I Sutw Swebim WA OP j Domirmni 101iinkl9doles Cvr CM SWO srrlun vr^ Fac ' z) M.¢ ATFi 71 SAC♦ rl s, R05 P Fe►G-f Rv f)%. ALRuJA C ep'n1 krweA WIL pMe U-1 O PA7�e0► rap O rwph rdrp O teeA M O 1111E pl-N dr1-�rr FACW at FAC A- h . rr.r. I).. R-Uoreb: )k2050% 0<"08L. FACW or FAC (no FAG)) O otlw NYormo�oa huW7 Y(N- ,&W Np dp1h: ' SrNtr (r in; eob)1 ! Depth d her 120 in p0wle: _�• Cow 1.1 O wear nwft O drN bw O rrafnwM drpo-1 O VA dnowl" pettenq OUrer M id eddrto- d -arbor huratlon or ed wprtllon Srow4wy hdorton: O oxWz*d roof dwwr.trtr o wstw•mahw I -ewe- O loal ad o )dos OFAC•Nrutrel Test (in vepw hydro) O other Aroaad Deft: qAkewn. bM or tuft gorge O swW photo O other O rww (ira-Yq aft -on Y on O drN QrOwt oroirlh p ell Wnp a 1e.r "t*FF O We1WW Nrgonrlr: F+1XI�.I+w SoL@ to e1 ft" Iv0 (00011% .uer cde,• `Nan.>�otarnn°rwnry C�..�. carter" 1AW& fQJ�. 0 Q Y© Y N L.. j YK YN YN YN. Y N Y N Y'•1s 'below A halts► or 1W tafte aviv eArloweQ Hydro Sol kdo-1 O HMtoed O NWo epbedon O Outdo Odor eA*M M-Mw 11410010 ; 0011kO wdudrtp w (tAweftow Chrona O High. 9trboe alp', Loom" in "Soft `...r Ode hybb eo/ YOidl 1P 8tNW ft h sandy Sob twk sdN wt . Mood, SOMA t n-ti-rtaMc � �M � • •�x .: 00m, �1-�! �perelM) no vp no soft no Mba Serr�Ob PeMM .+ wMendf y r i ft *b : FUNCTIONS AND VALUES HYDROLOGIC SUPPORT • Groundwater recharge (H WAl Groundwater discharge (H L Al Stream basellow, oontribu tQ WA) Floodwater attenuation (H N/Al Floodwater detention (H L Al Floodwater retention (H M; Al Floodwater attenuation (11 L Floodwatardesynchranizatlon (H UX N/A) WATER OUALITY FUNCTIONS Sedlmenthhorellne stabilization (H M L Retention of sediments, nutrients or (H 'N/AV Wql_ Trpnslorrnatlon of nutrients or t is (H M • Wistawaler treatment (H M L •W NATURAL BIOLOGICAL F NCTI S • Prkn" Productivity (H' WAI Orpartic aocmrnula H Al Organic export (H Deoonmpositlon (H M Al DoWW transport (H WA Nutrient cycling and util lion ( L WA, Food chain support (H WA HABITAT FUNCTI S • trtvertebrat" (H WAl A (H Al • Fisherbs (H M7 Mannmals H AI_ Birds (H L A Ho refuge (H M L N/A) SOCIO-ECONOMIC FUNCTIONS Non-oonsumptlw v —� Fleaeatlonel M� ... _ Aesthetic (H Hlstorlcal (H L N Archeological (H M ConsurnPtivo val Fished" (H M L o� A Renewable resou M L 1 Agricultural (H M L A WildYfe Data Plot Location sketch Ilk w1h PIE WETLAND DELINEATION DATA FORM Plot No. �6X ROUTINE OfVTF,DETERMINATION METHOD Transect ID Weather. 06►-^' Cowardl Field Invest brlAR TM MB - $Ize(ac): <0.5.<1-,I=2 Nor7 .. Conde? Dhttrbonw? Y Problem Area? YA4 J-- corer Clw 1. 0.5♦ 2.5 2.5 • IS♦ 15 3. 2S • W437.5 w 60. 75♦62.5 5. 75.954a5 6. >954 97.5 W& Purr app Cw Cie rndieator Suety WA. UP P1nd 8prdw Ca C1t rudioaler Slagrt sm— t=f►C♦ N FA�i- S FAC 14 L ! FAG M N110 p r W71 roar p wQ o p " o o "to 010on N O wll plats a.u�... %00L FACw FAC htnb • :jj lout llydrephylk v N national* *60!< 0<5MOal, FACW of FAC too FAG)) O Ww NYonoloor Ywrudr Y�N�.t N20 dpN: • SeMtr t5• ti candy rorlt)7 Y or fir• Ho im paw . ot>.er 1• r�aMw� O rutty writ. O do ion.. b rrahrr o WA. drebw90 pommm Otruer rra.NO.ro. of turrua wwndaWon at and salwallon ae andwy Ylftmm: n oxhked rod demsWlr o Master-WaMNd i"v" o 1ooW mA wrVwy ds1& OF , 706 tin vapor hydroq O oilw nroordad Dow O mew MM or Oda gauge O swW photo 0 oiler O none f Seam? m N {bed are O daN n o pargr- O so a t6.7' s11'F o 1�(�Ni�Nbnylr AO SOLO le at tna W 8erMiPMe* Taaataey 0mhspe paw Co*m WA&I mduramtAottl.Llcolor 9wTe9r. Y� Y'N O R5 YN YN L-s YN YN YN YN 'Eebw A hahon or IT Iwrde ever shafowar) wj" so irwloetN* O Ni.wrd O hallo ap pe" 0 s d1ft odor 0 Apub Moktm Poo w O Roaerg aamoftu O Gbp&' ow Chmomm O Nlat 8rrreoe dgrro Cw t t In Sw* soft a cowed" O owft stme fno In sw* soft Hy" Bob LYC " f � dJMlorelp, PAWN** .It1111110MIONAL INATIONAL! V400mr07 Y N PAW ISI : d perNa no v" 8enupM ports wain wadmid7 FUNCTIONS AND VALUES HYDROLOGIC SUPPORT Groundwater recharge (H M L N/Al Groundwater discharge (H M L NIA) • Stream basefiow Contribution (H M L N/Al Floodwater attenuation (H M L N/Al Floodwater detention (H M L NIAI Floodwater retention (H M L NMI Floodwater attenuation (H M L NIAI Floodwater desynchronization (H M L WA WATER QUALITY FUNCTIONS SedinlenVatloreline &WAzadon "(H M L N/Al Retention of sediments, nutrients or toxicants (H M L Will_ Transformation of nutrients or toxicants (H M L WA1 Wastewater treatment (H M L N/AL NATURAL BIOLOGICAL FUNCTIONS Primary productivity (H M L N/Al Organic accumulation (H M L WAI Organic export (H M L N/Al Decomposition (H M L WAI Detrital transport (H M L WAI Nutrient cycling and utilization (H M L WAl Food chain support (H M L WAI HABITAT FUNCTIONS • InveneWates (H M L NIAI . AmpNblans (H M L N/Al • Flahet'les (H M L WAI, Mammals (H M L WAI Bltdo (H M L WAI — Sanctuary and refuge (H M L WAl SOCIO-ECONOMIC FUNCTIONS Non -consumptive value Recreational(H M L NIA) Aeethatic (H M L WAI FWlorloal (H M,L NIA) Amh9ological (H M L WAl - Consumptive value Fisheries (H M L NIAI ' Rerwwable resources (H M L N/Al Agricultural (H M L WAl WtldNb iDoh Plot Location Sketch ( �•r I sr ,n PIE WETLAND DELINEATION DATA FORM Plot No. ROUTINE ONSITE DETEMMINATION METHOD Transact ID Wear . •' Cowardln ' D Projecf/Site: �` �,c . mr— �.,...� Date: 5/r e Field Invest i r;aVM MB - Size(ac): <0.5 <1 1 Normal Conde9 Disturbance? Pmbiern Area Cow Clasa I. 0. 5♦ 2.6 2-6.25415 3- 25 . W437.6 4- 50. 75462.5 5- 75.95495 6. >954 97.5 WA. oomYrry Plant SPP cvr Cr I kx0o"or Status Stalunr WA. UP mmkWA Plant spoon cvr CY trldlealar Status stratum 3 /Uto1u 3 I�VS P 27-A:4�Ar 3 110 N cWni snow U wa pry t o pnlnnpr aapl O morph t.oh It O WA plrN dam traw %091- F a FAX hwb ♦ 100 dwue ♦ a . Mat Nydraphye0 Vag (I N Ra waft 60% 0<50%(OeL. FACW or FAC (no FAG)) 0 odwr NYOQOLOOY burdr Y sud 1420 d.p1h: • sarlr w in sandy so agg:H Clapp o1 I.. N20 b pMwle Oaw 1• (rdoMora: 0 wgar ffWM 0 drM tin 0 ndinl d'po.aWA- dr.lrwp. pikes" Orwr Mod a Idw M ol surlow inundation or sod saturation S Mtrdoalon: ov� o oh A- Ir a watM•gyYwd lawn p loco ed OFACNnwy a.l. Raoadad Dam: 0 atr..m, Ww at ilea gauge 0 eadd photo 0 oars O nom Owwbv s.aao 116DILeased am Odom 0 s41'F 0 yyaearM AybalogytN Ratlorrata: _. �i tAlf 1�l r p••.... 00" to M MNt t9• �_ Mytrlc Ca1or' --raaaonomy na pan carom moo slam YN YN Z) YN YN YN YN YN YN 'bMow A horbon or W (Mddww dwbww) 9d trrdloarat 01-1 1 A 04astlo apb.don 0 8tAWo Odor P(Apulo MlolMara Regirm oondlorw A&imyeWww Chro m 0 Nloh surlaa Orprdo Corftn1 M s.ndy sow carrowsorra 0 ow a mesa g in sandy soft Nydrlo sac list: MUM Omar "b as bdbamra Nydd. 8917 N Rrttortalrx _ 0 TOr TION AND RAIMNALE 4 N Rtllaum o wag no es no trydrol Swoop potrN vrMdn wagan� N w - I 'VA . •.• FUNCTIONS AND VALUES HYDROLOGIC SUPPORT ' Groundwater recharge (H1tA L Al Groundwater discharge (H WA1 Stream basellow oontribu H ®L WAl Floodwater attenuation (H L WAl Floodwater detention (H M At Floodwater retention (H N/A1 Floodwater attenuation ( N/A) FloodiaaterdesynchroNza L WA WA, ER QUALITY FUNCTIONS 11 _ Sedlment/shorellne stabilization (H M L � AI Retention of sedirnents, nutrients or toxicanUH M L W/j_ • Transfor nadw of nutrients or is (H Qom_ WAl • Wastewater treatment (H M L(d/9Y NATURAL BIOLOGI FUNCTIONS Primary productivity AF t L N/A) Organic accumulation (WME WA) Organic export (H 1 Ib1K • Decomposition (H Al • Detrital transport ( M LL A Nutrient cycling and don (H WA , Food chain suppo L NIA) HABITAT FUNCTI •Invedebrates(H N/Al • AmpNblans (H WA1 • Fisheries (( IyL maninwel F('rMi(�/l, AI • A Sanctuary and re M L NIA) SOCIO-ECONOMIC FLWCTIONS • • Non -consumptive valyik-A ReaeatlwA (H M L A"thatio l[W M L MI WN Archeological is M L 4 Ardteologlcal (H M • Consumptive Value Fisheries (H M L Renewade rasou L A Agrlc tural IH M L W11104 Data Plot Location Sker2 tch i I ti�� • 03TREET FILE PLANNING DATA NAME: �� ®� SITE'ADDRESS: &LIE 72—DATE: 2� ZONING: %�J� ' Zip PLAN CHK#: �✓ PROJECT DESCRIPTION: CORNER LOT (Yes/No) FLAG LOT (Yes/No) SETBACKS: Required Setbacks:,�v Front:. Left Side: Right Side: Rear:_ Actual Setbacks: Front:_9 Left Side:/0Right Side: o2Z Rear: � Street map checked for additional setback required? (Yes/No) LEGAL NONCONFORMING LAND USE DETERMINATION ISSUED (Y/N) LOT COVERAGE: Maximum Allowed: J� o Actual: BUILDING HEIGHT: . Maximum Allowed: S Actual Height:��. 3� Datum Point:? (ai U�1.6bUttw� %� Datum Elevation: A.D.U. CREATED?: Vjb SUBDIVISION: CRITICAL AREAS #: SEPA DETERMINATI LOT AREA: NELSON-COUVRETTE & ASSOCIATES, INC. CONSULTWG GEOTECHNICAL ENGINEERS, GEOLOGISTS AND ENVIRONMENTAL SCIENTISTS 17311-135th Ave. NE, A-500 Snohomish County (206) 794-4332 Woodinville, WA 98072 (206) 486-1669 • FAX 481.2510 Wenatchee/Chelan (509) 784-2756 March 28, 1995 Mr. John. Johnson 16122 - 72nd Avenue West Edmonds, Washington 980264517 Preliminary Geotechnical Engineering Report Residential Development , Edmonds, Washington NCA File No. 145995 Dear Mr. Johnson: INTRODUCTION This report presents the results of our preliminary geotechnical evaluation for the portion of your property to be potentially developed. The site is located at 16122 - 72nd Avenue West, in the City of Edmonds, as shown on the Site Vicinity Map in Figure 1. You have requested that we prepare a preliminary geotechnical report to evaluate the site for development of potential residential housing. Mr. Jim Miller, of Lovell-Sauerland & Associates, Inc., has provided us with a site plan titled "Meadowdale Heights PRD Preliminary Grading Plan," dated March 9, 1995 by Lovell-Sauerland . & Associates, Inc., showing the proposed site layout for the project. You desire an evaluation of slope stability and general earthwork parameters. We have been informed that at this time a reconnaissance report evaluating development potential of the property is desired. Additional work may be required regarding specific sensitive area issues, prior to platting. That additional work is beyond the scope of this report. The site slopes moderately to steeply down towards North Meadowdale Road. The. site layout provided to us indicates that potentially seven buildings, along with a new access road, are proposed for construction along the upper portion of the slope and the knob at the west end of the site. Based on the plan provided, it appears that up to an 11 foot cut would need to be made for the access roadway. 'The residences may incorporate daylight basements into their design. Preliminary Geotechnical Egeering Report . • Residential Development - Edmonds , March 28, 1995 NCA File No. 145995 Page 2 SCOPE The purpose of this study is to explore and characterize the subsurface conditions, and present: general geotechnical recommendations for site development. Our report is intended to identify foundation soil types, and provide an evaluation of slope stability and general earthwork parameters for site development. Specifically, our scope of services include the following: r 1. Review available geologic or soils data for the site from published geologic maps. 2 Explore the subsurface conditions at the site with hand.explorations to identify subsurface soils and hydrologic conditions. 3. Measure cross -sections through the site in the field using a hand level and a 100 foot tape. 4. Provide an evaluation of slope stability of the site. 5. Provide preliminary earthwork guidelines. 6. Prepare a written report to document our findings and recommendations. SITE CONDITIONS Surface The trapezoidal shaped site is located on the south side of North Meadowdale Road, as shown on the Site Plan in Figure 2. We have labeled the proposed residence locations for descriptive purposes. An existing residence is located on the upper level portion of the site. The hillside then slopes moderately to steeply down to the north and to the natural drainage area alongside the roadway. In the northwest portion of the site, a knob extends to the north from the upper level area creating a slightly less steep slope at the west end of the site, in the vicinity of units A, B and C. The preliminary grading plan we were provided, identifies the drainage area as a wetland with an associated 50 foot buffer area. The total vertical relief within the site is approximately 140 feet. The slope angles as interpreted from the topographic grading plan show the hillside slopes at approximately 31 degrees over most of the slope, and approximately 27 degrees below the knob at the west end of the site. The steeper areas incline -at approximately 35 degrees. We performed two slope surveys at the site using a clinometer and a 100 foot measuring tape. These surveys measured the steeper portions of the slope to be on the order of 35 degrees. This is in general agreement with the topographic plan. NELSON-COUVRETTE & ASSOCIATES, INC. Preliminary Geotechnical EnIkering Report • Residential Development - Edmonds March 28, 1995 NCA File No. 145995 Page 3 The slope is vegetated with medium to large diameter trees along with thick underbrush of ferns and blackberry bushes. We observed two fallen trees and a few trees with slightly bowed trunks. However, the majority of the trees were straight. There is a series of trails on the slope, which in places have been cut into. the hillside. Light brown medium sand was observed in these cut areas. Portions of the slope are covered with landscaping debris such as branches and cut trees. It appeared that some vegetation had been pushed over the top of the slope and/or was cut and left on the slope when the trails were created. We did not observe obvious areas of fill. The lower wetland area is overgrown with blackberry bushes, brush and scattered trees. There was standing water in the drainage draw at the time of our visit. Geology The Preliminary Surficial Geologic Mgp of the Edmonds East and Edmonds West Quadrangles Snohomish and King Counties. Washington by Mackey Smith (Washington Department of Natural Resources, 1975) was referenced for information about the area geology. This map delineates the soils in the vicinity of the site as Esperance Sand (Qe) overlying the Whidbey Formation (Qw). An area defined as Old Landslide (Qols) is mapped to the west. We reviewed the Cityof Edmonds critical areas ordinance (No. 2874) and .have reviewed the associated reports by GeoEngineers, Inc. and Rodger Lowe & Associates, Inc. with regard to the Meadowdale Slide area. This site is mapped as being associated with the Meadowdale slide complex. It is classified as a 31302 area. This classification identifies the site as being underlain by material that has not failed in the past, and has a 2 percent probability of debris slides occurring due to the steep slopes, in 25 years. The sediments classified as Whidbey consist of well sorted beds of clay, silt or sand. The Esperance is a unit within the advance outwash which is generally a medium to coarse sand with trace amounts of fines and varying gravel content. The Esperance sand contains a low percentage of fine grain particles. It has moderate to high strengths when confined. However, in sloping areas the outer portions can become loose. Advance outwash was deposited at the base of advancing glaciers. The Whidbey and Esperance, therefore, have been overridden by past intrusion of continental glaciation. The last period of glaciation, the Vashon Stade, ended approximately 11,000 to 13,000 years ago. During the Vachon Stade, the Puget Sound region was overridden by over 3,000 feet of ice. Soil layers overridden by the ice sheet were compacted. to a much greater extent than those that were not. NELSON-COUVRETTE & ASSOCIATES, INC. Preliminary Geotechnical En*neering Report • Residential Development - Edmonds March 28, 1995 NCA File No. 145995 Page 4 Subsurface The hillside subsurface conditions,were explored on March 6, 1995 with five shallow hand auger borings on the sloping portion of the site. The hand explorations were located in the field by a geological engineer, representing this firm, who maintained logs of the conditions encountered. The locations of the hand explorations are shown on the Site Plan in Figure 2. The soils were classified in general accordance with the Unified Soil Classification system, a copy of which is presented on Figure 3. The hand auger logs, edited to reflect examination of soil samples in our laboratory, are presented as Figure 4. Our hand explorations were advanced to depths of 2.3 to 4.5 feet below existing grade. At depth, in Hand Augers 1 through 4, we encountered a unit of loose to medium dense, brown medium sand with trace silt and fine gravel, the top of which extended up to a depth of 1.2 to 2.0_ feet below grade. These soils are interpreted to be the Esperance Sand. In Hand Auger 5, this unit was observed to contain a greater amount of silt, possibly indicating it is part of the advance sand sequence. In Hand . Augers 1 through 3, the Esperance sand was overlain by 1.3 to 2.0 feet of loose, brown fine to medium sand with some to trace silt. This unit is interpreted to be weathered Esperance sand. In Hand Auger 4, the Esperance sand was overlain by 0.6 feet of dark brown organic sandy silt, interpreted to be a buried topsoil horizon. This horizon was overlain by 0.4 feet of loose, brown medium sand, interpreted to be slope wash. Slope wash is material deposited by erosional processes. Hand Augers 1, 4 and 5 were capped with a surficial layer of forest duff, approximately 0.6 to 0.2 feet thick. Our explorations were shallow in depth. The types of soils observed on the site typically grade to a more dense condition with depth. Hydrologic We did not observe ground water seepage within any of our explorations. Surface water was observed in the drainage draws within the wetland area. We expect that this water is perched on a less permeable underlying soil. Although we did not find evidence of ground water in the slope, local areas with perched ground water are possible above silt lenses or layers that can exist within this deposit. Perched ground water is not associated with a regional ground water table, and will vary depending upon the amount and duration of precipitation. SLOPE STABILITY We did not observe signs of deep seated instability on the slopes. We observed numerous older fir trees, approximately 1.0 to 1.5 feet in diameter, on the slope. Their presence is an indication that the slope is not active with regard to deep seated or significant shallow earth movements. We did observe a couple of trees NELSON-COUVRETTE & ASSOCIATES, INC. Preliminary Geotechnical Elkeering Report • Residential Development - Edmonds March.28, 1995 NCA File No. 145995 Page 5 with bent trunks at the base. This is usually an indication that some surface soil creep is occurring. The soils exposed on the moderate to steep slopes are a clean sand that we would expect to be susceptible to slough type failures and erosion. This type of slope movement is typically shallow. CONCLUSIONS AND RECOMMENDATIONS General The project site should be compatible with the proposed development, providing that site grading and construction are designed and implemented to maintain and/or increase the existing site. stability. We expect that the density of the surficial sands will increase with depth, but this should be evaluated prior. to construction. The native soils are expected to be stable with respect to deep seated failures. The upper soils are weathered and less dense and should be considered near their natural angle of repose on the slope face. Once disturbed, these soils have a moderate to high degree of erosion. We recommend that erosion on these. slopes be controlled. This is discussed in the Erosion sub -section. We would expect sloughing type failures from cuts in the upper loose to medium dense soils. The site is mapped as being a part of the Meadowdale slide complex that. has not moved in the recent past. It is mapped as having a small potential for debris slide., type movements or sloughing events. It is our opinion that if proper drainage and erosion control measures are taken, the potential development should have a minimal impact on the stability of the slopes on the site. Our specific recommendations are presented in the Erosion and Drainage sub -sections. Foundations for the planned residences should be supported on the underlying medium dense or better glacial deposits. The foundations on the hillside should have a minimum 15 foot horizontal buffer between. the slope surface and the outside edge of the footing. This may be accomplished by extending the footings below.grade. It is possible that this buffer could be reduced after review of site specific conditions. Based on the preliminary grading plan provided, it appears that a cut up to 11 feet high will be made for the access roadway and the buildings may incorporate a daylight basement into their design. The road cut will require some type of retaining structure. Based on the soil conditions encountered we do not recommend the use of rockeries greater than 4 feet in height unless specifically designed as a retaining structure. Types of retaining structures. applicable for this site are concrete retaining walls or a gravity retaining structure such as a reinforced earth fill. A reinforced soil wall is constructed with reinforcing geogrid or geotextiles placed in the compacted backfill. The reinforcing typically extends 50 to 80 percent of the wall height back from the wall face. These walls require a facing such as rockeries or concrete blocks on the exterior NELSON-COUVRETTE & ASSOCIATES, INC. Preliminary Geotechnical E*eering Report Residential Development - Edmonds March 28, 1995 NCA File No. 145995 Page 6 surface. For daylight basement construction the basement wall will need to be designed as a retaining wall. The design of retaining structures is beyond the scope of this report. Erosion Control The on -site soils have moderate to high erosion potential when disturbed and exposed on slopes. . If construction is to take place during the wet season, we recommend that slopes disturbed during construction be protected from erosion. Measures taken may include diverting surface water away from the top of slopes, and covering slopes with straw or plastic sheeting. Erosion fences may be constructed at the base of construction areas to prevent run off from entering the wetland area. All slopes where the soil is exposed, should be compacted and re -vegetated, after construction, to reduce erosion. The vegetation should be maintained and repaired until it is established. Where the existing vegetation is not disturbed, erosion potential should not be significant. 4 Site Preparation and Grading Areas to receive pavements, slabs -on -grade or structural fill should be stripped of any surficial topsoils layer or duff. Foundation subgrades should be prepared as outlined in the Foundation sub -section. After stripping, pavement areas should be -compacted with a large vibratory roller. Areas observed to weave under compaction equipment should be repaired prior to paving or casting slabs -on -grade. The on -site soils are slightly to moderately moisture sensitive. The need for a blanket of rock spalls at the access roadway should be evaluated at the time of construction. For estimating purposes, we recommend using a minimum one foot thickness of rock spalls for the access roadway. 'The amount and thickness of the spall blanket will vary, depending upon the conditions, when the site is developed. Structural Fill All fill placed beneath buildings, pavements or other settlement sensitive features, should be placed as structural fill. Structural fill, by definition, is placed in accordancewith prescribed methods and standards, and is monitored by an experienced geotechnical professional or soils technician. Field monitoring procedures would include the performance of a representative number of in -place density tests to document the attainment of the desired degree of relative compaction. The degree of compaction to be obtained is dependent on the type of structure to be placed on the structural fill. The degree of compaction to be obtained for this project can be developed in the future and is dependent upon City of Edmonds standards and good engineering judgment. NEL SON- COUVRETTE & ASSOCIATES, INC. Preliminary Geotechnical Joeering Report Residential Development - Edmonds March 28, 1995 NCA File No. 145995 Page 7 Temporary and Permanent Cut Slopes We recommend that temporary cut slopes be no steeper than 1:1 (H:V) in dense sand and 1.5:1 (H:V) in the upper loose to medium dense zone. Slopes closer to 1.5:1 (H:V) in dense sand will have a better face performance. When using the steeper slopes, there is risk of some sloughing. We have observed that the preliminary grading plan indicates a 5 to 10 foot wall is to be constructed below the existing residence. If the toe of the cut for the wall lies within a 1.5:1 (H:V) line extending out from the existing building, temporary shoring measures may be needed. We do not recommend vertical slopes for cuts deeper than 4 feet, if worker access is necessary. We recommend that cut slope heights and inclinations conform to appropriate local, state and federal regulations. Because of the many variables involved, the above estimates for temporary cut slopes should be considered a general guideline. The actual slopes angles should be made the responsibility of the contractor, as he is continuously present at the job site to observe the nature and condition of the excavation soils. Temporary slope erosion protection and raveling maintenance should be expected during construction. Permanent new slopes constructed of cut slopes or structural fill should be no steeper than 2:1 (H:V). A 2:1 (H:V) slope angle is recommended to minimize slough failures and excessive maintenance. Lightly compacted fills, or common fills, should be no steeper than 3H:1V. Common fills are defined as fill material with potentially some organics that are "trackrolled" into place. They would not meet the compaction specification of structural fill. Flatter slopes would require even less maintenance. All slopes should be vegetated with a suitable cover and the vegetation maintained until it is well established. Jute netting or straw should be used to reduce erosion while the vegetation is being established. We have observed that the preliminary grading plan indicates areas with permanent slopes steeper than 2:1 (H:V). These areas are the slopes just south of unit A, and between units C and D. These slopes should be graded back to 2:1, or an appropriate retaining system should be used. Foundations We recommend that the structures be founded on conventional spread footings.. Footings should bear on the underlying medium dense or better native soils or structural fill extending to these soils. The foundations on the hillside should have a minimum 15 foot horizontal buffer between the slope surface and the outside edge. of the footing. This buffer may be achieved by extending footings below the existing ground .surface. It is possible that this buffer could be reduced after review of site specific conditions. Minimum foundation widths of 18 and 24 inches should be used for continuous ' and isolated spread footings, respectively. Footings should be embedded a minimum of 18 inches for frost protection. NELSON-COUVRETTE & ASSOC/A TES, INC. Preliminary Geotechnical Efleering Report • Residential Development - Edmonds March 28, 1995 NCA File No. 145995 Page 8 Standing water, water loosened soils and slough should be removed from the foundation excavation prior to placing concrete. For foundations constructed as outlined above and founded on an undisturbed native soil, we recommend an. allowable design bearing pressure of 2,000 pounds per square foot (psf) to be used for the footing design. The foundation bearing soil should be evaluated by a representative of our firm. The Puget Sound region is classified as a Zone 3 by the Uniform Building Code. A one-third increase in the above allowable bearing pressure may be usedwhen considering short-term transitory wind or seismic loads. Drainage The finished ground surface should.be graded such that storm water is collected and directed off the site. Concentrated water run off should not be allowed to discharge onto the slopes. Final site grades should allow for drainage away from the building. We suggest the finish ground be sloped at a gradient of 3 percent minimum for a distance of at least 10 feet away from the building, except in the areas that are to be paved. Storm water should not be drained onto the sloped areas of the site. Surface water should be collected by permanent catch basins and drain lines and be discharged into a storm drain system. Perimeter footing drains should be installed at the base of all perimeter footings. Subsurface walls should be provided with wall drainage systems. Roof drains should not be connected to perimeter footing drain or wall drain systems. USE OF THIS REPORT AND WARRANTY We have prepared this report for Mr. John Johnson and his agents, for use in preliminary planning and design of this project. The data and report should be provided to the contractor for their estimating purposes, but our report, conclusions and interpretations should not be construed as a warranty of subgrade conditions. The purpose of this report is to provide preliminary, general recommendations for site development. Our work was based on a limited number of shallow explorations, and our recommendations should not be considered adequate for final design. It is likely that additional explorations and geotechnical evaluation will be required as development plans proceed. The scope of our work does not include services related: to construction safety precautions, and our recommendations are not intended to direct the contractors' methods, techniques, sequences or procedures, NELSON-COUVRETTE & ASSOCIATES, INC. Preliminary Geotechnical Ecfneering Report • Residential Development - Edmonds March 28, 1995 NCA File No. 145995 Page 9 except as specifically described in our report for consideration in design. There are possible variations in subsurface conditions. We recommend that project planning include contingencies in budget and schedule, should areas be found with conditions that vary from those described in this report. Within the limitations of scope, schedule and budget for our services, we have strived to take care that our work has been done in accordance with generally accepted practices followed in this area at the time this t report was prepared. No other conditions, expressed or implied, should be understood. I We appreciate the opportunity to be of service to you. If there are any questions concerning this report or if we can provide additional services, please call. Sincerely, NELSON-COUVRETTE & ASSOCIATES, INC. 5Y William B. Benzer Project Engineer iA Al. titi o� AS fik�'o 19421 - IST NAL16 EXPIRES ()?- f—%J6 William M. Kuck, PE Senior Engineer Three Copies Submitted Four Figures cc: Mr. Jim Miller - Lovell-Sauerland & Associates, Inc. EXPIRES (o•�'j alb Charles P. Couvrette, PE Principal Engineer NELSON-COUVRETTE & ASSOCIATES, INC. I VICINITY MAP I NELSON-COUVRETTE &ASSOCIATES, INC. JOHNSON FIGURE 1. 1 CONSULTING GEOTECHNICAL ENGINEERS, GEOLOGISTS AND ENVIRONMENTAL SCIENTISTS FILE NO. 145995 DATE MARCH 1995 SOIL CLASSIFICATION SYSTEM GROUP MAJOR DIVISIONS SYMBOL GROUP NAME COARSE GRAVEL CLEAN GRAVEL GW WELL -GRADED GRAVEL, FINE TO COARSE GRAVEL GRAVEL GP POORLY -GRADED GRAVEL GRAINED SOILS MORE THAN 50% OF COARSE FRACTION RETAINED ON WITH FINES GM SILTY GRAVEL NO.4 SIEVE GC CLAYEY GRAVEL MORE THAN50% RETMED ON NO.2W SIEVE SAND CLEAN SAND SW WELL -GRADED SAND, FINE TO COARSE SAND SP POORLY -GRADED SAND MORE THAN 50% OF COARSE FRACTION PASSES No. 4 SIEVE SAND SM SILTY SAND SC CLAYEY SAND WITH FINES FINE SILT AND CLAY INORGANIC ML SILT CL CLAY GRAINED LIQUID uMrr LESS THAN so% ORGANIC OL ORGANIC SILT, ORGANIC CLAY SOILS SILT AND CLAY INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT CH CLAY OF HIGH PLASTICITY, FAT CLAY , MORE THAN 509E PASSES NO.2W SIEVE LIQUID LIMIT 50% OR MORE ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: SOIL MOISTURE MODIFIERS 1) Field classification is based on Dry - Absence of moisture, dusty, dry visual examination of soil in general to the touch accordance with ASTM D 2488-83. Moist - Damp, but no visible water 2) Soil classification using laboratory tests is based on ASTM D 2487-83. Wet - Visible free water or saturated, usually soil is obtained from 3) Descriptions of soil density or - below water table consitency are based on interpretation of blowcount data, - visual appearance, of soils, and/or test data. NELSON-COUVRETTE &ASSOCIATES,1Nc. SOIL CLASSIFICATION SYSTEM CONSULTING GEOTECHNICAL ENGINEERS, GEOLOGISTS ANO ENVIRONMENTAL SCIENTISTS .FIGURE 3 • LOG OF EXPLORATION Is III I . DEPTH USC SOIL DESCRIPTION I HAND AUGER ONE 0.0 - 0.4 BRANCHES, STICKS AND DUFF (VERY LOOSE, MOIST) r 0.4-1.7 SP-SM BROWN FINE TO MEDIUM SAND WITH SILT, TRACE ROOTS AND GRAVEL I (LOOSE TO MEDIUM DENSE, MOIST) 1.7-2.3 SP BROWN MEDIUM SAND WITH GRAVEL, SCATTERED COBBLES AND TRACE SILT (LOOSE TO MEDIUM DENSE, MOIST) (Qe) SAMPLES WERE COLLECTED AT 12 -1.7 AND 1.9 - 2.3 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 2.3 FEET ON 3/6/95 IHAND AUGER TWO 0.0-2.0 SP LIGHT BROWN MEDIUM SAND WITH TRACE SILT AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) I 2.0 - 3.5. SP TAN -GRAY MEDIUM SAND WITH TRACE SILT (MEDIUM DENSE, MOIST) (Qe) SAMPLES WERE COLLECTED AT 1.1 -1.6 AND 2.8 - 3.2 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED I HAND AUGER WAS COMPLETED AT 3.5 FEET ON 3/6/95 HAND AUGER THREE I 0.0-2.0 SP LIGHT BROWN MEDIUM SAND WITH TRACE GRAVEL AND SILT (LOOSE, DAMP TO MOIST) 2.0 - 3.0 SP . TAN -GRAY MEDIUM SAND WITH TRACE GRAVEL AND SILT (LOOSE TO IMEDIUM DENSE GRADES TO MEDIUM DENSE, MOIST) (Qe) SAMPLES WERE COLLECTED AT 1.5 - 2.0 AND 2.5 - 2.9 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED IHAND AUGER WAS COMPLETED AT 3.0 FEET ON 3/6/95 HAND AUGER FOUR 0.0-0.2 DUFF 0.2 - 0.6 SP LIGHT BROWN MEDIUM SAND WITH TRACE SILT (VERY LOOSE, DRY TO MOIST) (SLOPE WASH) I 0.6 -1.2 ML DARK BROWN TO BLACK ORGANIC SANDY SILT,,(SOFT, DAMP TO MOIST) j (BURIED TOPSOIL) 1.2-4.5 SP LIGHT BROWN MEDIUM SAND WITH TRACE GRAVEL AND SILT (LOOSE TO DENSE GRADES TO MEDIUM DENSE, MOIST) (Qe) IMEDIUM SAMPLES WERE COLLECTED AT 0.6 -1.0 AND 4.0 - 4.5 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED I HAND AUGER WAS COMPLETED AT 4.5 FEET ON 3/6195 HAND AUGER FIVE 0.0 - 0.6 DUFF 0.6-2.5 SM LIGHT GRAY RUST BROWN MOTTLED SILTY FINE TO MEDIUM SAND WITH GRAVEL AND SCATTERED COBBLES (MEDIUM DENSE, MOIST) (Qe) SAMPLES WERE COLLECTED AT 1.3 -1.8 AND 2.0 - 2.4 FEET GROUND WATER WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 2.5 FEET ON 316MS NELSON-COWRETTE & ASSOCIATES, INC. FILE NO.145995 FIGURE 4 Ih c.1890 STREET FILE V/ /6//8 72-- f1P2 N/ CITY OF E D M O N D S GARY HAAKENSON MAYOR 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 • FAX (425) 771-0221 Website: wwwxi.edmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT Planning • Building • Engineering February 23, 2005 John E. Thoreson 16118 72nd Avenue West Edmonds WA 98026 Re: Meadowdale Drainage Improvements Dear Mr. Thoreson: We are in receipt of your letter of February 14, 2005 to Jeannine Graf. Please note that we are in disagreement regarding many of the assertions contained in your letter. First, the City's Meadowdale drainage improvements are designed to protect the public right of way and the City's sewer improvements in the area. They are not now nor have they ever been designed to protect individual private properties. The dewatering of the Meadowdale landslide mass has had a positive impact on the overall probability of earth movement in the area. The particular drainage improvement that you refer to are. on the lower third or quarter of t:.e steep slope and provide additional stability to downslone areas by dewatering the hillside. The improvements were neither designed nor intended to stabilize the upslope portion of the property. Secondly, the City has investigated reports of slides at this specific site since 2001. Repeated investigations have been performed for the City by its geotechnical experts, Landau Associates. Those reports have consistently found that the slide at the top of the slope is unrelated to the City's drainage improvements or their maintenance. The reports provided to the City indicate that the landslide activity which has occurred was most likely caused by inclement weather as a part of the natural process of surfical earth movement in that area. In a nutshell, the slope is in the natural process of retreat. Subsequent slides have occurred along cracks relating to the initial slide. As you know, there were questionable construction practices at the Bosch site in 2001 which may or may not have contributed to the earth movement. The geotechnical reports provided by Landau Associates and others do not support the assertion you make in your letter that the slope is failing from the bottom up. The City has documented the successive slides both through photographs and through the reports of its consultant. That information clearly indicates that the slides are occurring from the top down due to inclement weather and the natural process of slope retreat at that location. IWSS593941.DOC;1/00006.900000/) 0 Incorporated August 11, 1890 • John E. Thoreson February 23, 2005 Page 2 Next, it is correct that the City has ceased to maintain the specific drainage improvement referenced in your letter. Maintenance was suspended in December of 2001, when debris from tree topping blocked access. The City ceased maintenance activity altogether on March 6, 2002, because the hillside was unsafe for maintenance workers. There was no safe way to maintain that portion of the improvement. It is also highly probable that the improvement was damaged during the course of the slides. Review of the line by a TV monitor indicated that it was distorted in shape and blocked by debris. Because of the instability of the slope, the City has not attempted to maintain or repair that catch basin and piping, but rather initiated a process to replace it with another improvement. On October 25, 2002, R.W. Beck was commissioned to design a new improvement. On August 26, 2003, the City awarded a construction contract, and on September 10, 2003, a preconstruction meeting was held with the contractor. On September 16, 2003, immediately prior to the date on which work was to commence under this contract, a new slide occurred above the area where the work was to be done, again rendering the site unsafe for construction workers to work in the area. Accordingly, that contract was terminated. The City is currently in the process of redesigning the improvement. The improvement, however, will be located at the bottom of the slope and is intended to catch the seepage from the hillside at a location which continues to serve its purpose -- protection of the City's sanitary sewers and public right of way. The improvement will be located where it can be safely maintained given the ongoing instability of the hillside behind it. You assert that the developer of Lorian Woods - presumably Dr. Robert Anderson, has indicated to the City that catch basins and related drain pipes have been removed and not replaced. I have no record of any such communication. Finally, the City will continue to maintain its improvements, in this case through replacement. There are no plans to extend the City's storm drainage system in this area. Sincerely, .) RUANE V. BOWMAN Development Services Director cc: Phil Holroyd John Johnston Jim Bosch (WSS593941.DOC;1/00006.900000/) FEB.15.2005 10:23AM M.B.S. NO.114 P.2/3 February 15, 2005 Ms. Jeannine Graf City of Edmonds 121 5"" Ave N. Edmonds, VITA 98020 DELIVERED BY FACSIMILE-: 425-771.0221 Dear Ms. Graf STREET FILE /(a//8 7L Avg W SUiLD1NG DEB A 5 INS Another mudslide/debris flow has occurred on the west slope between the Sequoia. Ridge Plat and the Lorian Woods Plat. Again, there is water seepage emerging from the slope 30 to 35 feet below the top of the slope beyond the property line of the Sequoia Ridge Development in the middle of the slide area. This is now the third such incident since December of 2001, where mudflows/slides have occurred and water seepage is evident. As determined by both Landau Associates and GeoGroup Northwest the seepage observed at the base of all these mudflows is in the vicinity of the City of Edmonds storm drain system on the slope between Sequoia Midge and Lorian Woods. The City of Edmonds required that I retain a geotechnical engineer after the slide on December 16, 2001. Our engineers clearly pointed out to the City of Edmonds that: " the City and private seepage collection and drainage system must be maintained on a regular basis." The recommendation farther stated: "a new seepage collection system be installed where the water seepage emerges. Filter fabric and crushed rock needs to be placed where the water seepage emerges and new catch basins and drains should be installed to capture the water and minimize erosion of the slope." The engineer goes on to say: " if these measures are not implemented the rate of bank recession could be faster than anticipated." 7be recommendations of the geotechnical engineer have never been implemented. The storm drain system between Sequoia Ridge and Lorian Woods has not been maintauned. Over the past year there has been clearing activity on Lorian Woods property below the Bosch house in Sequoia Ridge where these drain systems could have been further compromised. These slides as indicated by professional geotechnical engineers are occurring from the bottom up as opposed to the top down. Water seepage from the slope is causing erosion and undermining the slope above the seepage area thus causing the slides and mudflows. The developer of the Lorian Woods project has indicated to the City of Edmonds that water seepage catch basins and related drain pipes have been taken out and never replaced. Due to the fact that this in now the third occurrence of debris/mudflow in the vicinity of the City's storm drain system on the Lorian Woods property and the fact that none of the recommendations of the geotechnical engineer have been completed after the December 16, incidence, I am requesting a timetable by the City of Edmonds as to when the storm F'E3.15.2005 10:23AM M.B.S. NO.114 P.3/3 drain system will be repaired/replaced or a new system installed as recommended by the geotechnical engineer. I will await your response. Should I not receive an adequate response within the next 10 days, I will band this matter over to legal counsel for immediate action. Sincerely, ohn E ioresen 16 72" d Ave W. Edmonds, WA 98026 CC. Mx. Phil Holroyd, 16120 72°d Ave W. Mr. John Johnson, 16122 72°4 Ave W. Mr. Jiro Bosch, 16116 72"d Ave W. Duane Bowman, Director of Development Services Dave Gebert, City Engineer ZZer Zeman Associates I Y • Geotechnical and EnVREET ental Consulting FILE J-720 May 5, 2000 City of Edmonds Community Services Department 50 5h Avenue North Edmonds, Washington 98020 Attention: Ms. Jeannine Graf, Building Official Subject: Geotechnical Review Proposed Thoresen Residence, Lot 2 of Sequoia Ridge 6521 8 Place WesPlace Wes ' ��mgton Dear Ms. Graf: This letter presents our conclusions and recommendations concerning our geotechnical review of building permit application documents for the referenced project. These services were requested with your letter of transmittal dated March.29, 2000. The plan review number for this project is 00-115. Zipper Zeman Associates, Inc. services were limited to geotechnical review for the referenced project. These preview services do not include design, analysis, or engineering recommendations for the project. These review services were provided for the purpose of evaluating general conformance of the documents with City of Edmonds permit requirements. These services were provided for the exclusive use of the City of Edmonds for specific application to the referenced project and purpose. No other warranty is expressed or implied. Ordinance No. 2661 of the City of Edmonds, dated January 27, 1988 and revised February 29, 1988 contains requirements for design, geotechnical analysis, construction, and permit submittal within the Meadowdale Slide area of Edmonds. Paragraph 19.05.000 of the ordinance defines the purpose of the ordinance. Paragraph 19.05.030 describes required application submissions. The following sections of this letter contain -our conclusions _regarding the submissions for this project, including conformance with the required application submissions noted in the ordinance. Additionally, this letter comments on conformance with Paragraph 19.05.050 of the ordinance, which describes disclosures, declarations, covenants, and waivers required for construction in the Meadowdale Slide area. A summary of the submittal status, as pertaining to geotechnical information, is enclosed with this letter. After we receive additional information, particularly the grading plan to sufficient detail, additional review items may develop. Based on our initial review and our understanding of the building permit submittal requirements, we recommend that the geotechnical report be supplemented as noted below. 19231 — 36i° Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771— 3304 J720,050500 ' 4 . City of Edmonds 0 Thoresen Residence, Lot 2 of Sequoia Ridge • J-720 May 5, 2000 Page 2 • The engineer interprets the depth to groundwater as greater than 30 feet on Lot 2, although Boring B-2 encountered seepage in the upper 2 or 3 feet during May 1999. The conclusions of the report, including stability of the west -facing slope, driveway cut and east -facing slope, should be re-evaluated in consideration of the probable seasonal presence of perched groundwater at higher elevation than assumed. • In general, we are of the opinion . that the City of Edmonds requirement that "employing all feasible attendant measures" to reduce the risk of earth movement requires that an engineered retaining structure be used, in lieu of rockeries. The engineer should re-evaluate the use of tiered rockeries, and rockeries in the height range proposed. �r • The plans seem to indicate that a rockery will be constructed west of the house at the "15 foot undisturbed area line". We expect that excavation for the rockery will extend into the 15 foot setback. The engineer should provide criteria to avoid disturbance in this .area. • Geologic mapping of the west -facing slope would be a reasonable means of providing a geologic cross-section for stability evaluations. The subsurface profile B-B' in the geotechnical report does not accurately reflect the planned setback and grading. Because the stability of the slope in question affects the foundation support, we recommend that it be analyzed in sufficient detail to confirm that static and seismic factors of safety exceed building code requirements. • Similar stability evaluations are recommended for the east -facing slope. We recommend that a numerical factor of safety be calculated for all graded areas, and areas supporting foundations. • The engineer seems to base his conclusions regarding stability on the probabilities described in the GeoEngineers report and predecessor report. It is our interpretation of the City's requirements that the engineer should independently determine the statistical probability of earth movement within a 25-year period, the susceptibility of the risk or hazard to correction by on -site improvement, and the measures taken to mitigate the risk or hazard. We recommend that the City determine whether this requires the property owner to mitigate the risk posed by the west -facing slope to downslope property. The engineer recommends that specific foundation pile lengths be studied after topography of the west -facing slope is better defined. We recommend that geologic conditions at depth also be better defined, and the stability of .the pile supported house be analyzed in greater detail. The 25-foot setback recommended . by the engineer should be compared to criteria referenced in UBC Section 1806.5.3. 19231 — 36'" Avenue W., Suite B201 Zipper Zeman Associates_ Inc. Lynnwood, Washington 98036 (425) 771— 3304 J720,050500 City of Edmonds Thoresen Residence, Lot 2 of Sec�oia Ridge • J-720 May 5, 2000 Page 3 We appreciate the opportunity to have provided this review. Please feel free to call if you have any questions or need additional information. Respectfully submitted, Zipper Zeman Associates,, Y WAS,FII, John E. Zipper, P. E. President Enclosure: Summary of Submittal Status: May 5, 2000 Zipper Zeman Associates, Inc. 19231— 36t° Avenue W., Suite B201 Lynnwood, Washington 98036 J720,050500 SIOISTE�Gti�4� NAL EXPIRES 1 / 24 / a ��v s (425) 771 — 3304 5 City of Edmonds Thoresen Residence, Lot 2 of Sequoia Ridge Enclosure Proposed Thoresen Residence, Lot 2 of Sequoia Ridge 16521 48`h Place West Edmonds, Washington • J-720 May 5, 2000 Page E-1 Summary of Submittal Status Ordinance No. 2661 of the City of Edmonds, dated January 27, 1988 .and revised February 29, 1988 contains requirements for design, geotechnical analysis, construction, and permit submittal within' the Meadowdale Slide area of Edmonds. Paragraph 19.05.000 of the ordinance defines the purpose of the ordinance. Paragraph 19.05.030 describes required application submissions. The following sections of this summary contain our conclusions regarding the submittals received by our office for this project, including conformance with the required application submissions noted in the ordinance. Additionally, this summary comments on conformance with Paragraph 19.05.050 of the ordinance, which describes disclosures, declarations, covenants, and waivers required for construction in the Meadowdale Slide area. The site evaluation checklist utilized for this review is titled "Meadowdale Earth Subsidence Landslide Hazard Area Checklist for Permit Submittal" and appears to be dated May 1999. The status of the submitted geotechnical report by Geo Group Northwest, Inc. dated February 29, 2000 is summarized below: The following submittals are required by the referenced ordinance: Critical areas determination — Not submitted for our review. 2. Lead design professional designation and statement — Reviewed; Does not include the required statement that engineer has. "incorporated into. the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report." 3. Vicinity Map,— Complete. 4. Topographic Map — Reviewed; Does not show topography of west -facing slope on subject property. Does not show locations of "known landslide masses or debris flows on or near the site which could threaten proposed structures within 100 feet." Page 6 of the geotechnical report notes that evidence of recent sliding was present on the steep slope in the westpart of lots 2 and 3. 5. Environmental Checklist — Complete; also reviewed EIS. 6. Land Clearing/Tree Cutting Plan — Plan sheet "Site" by. Bientz Architectural dated 11/16/99, revised 2/28/2000 shows tree locations. A Land/Clearing Tree Cutting plan of the specified detail was not submitted for our review. Given the nature of the site, we recommend that a detailed clearing/TESC plan be submitted and reviewed. Geotechnical Report — The geotechnical report is required to discuss all items within the referenced checklist and to make specific recommendations, as listed in the "Geotechnical Report Guidelines" dated May 1999 by the City of Edmonds. Our comments regarding the geotechnical report are contained in our letter dated May 5, 2000. 8. Drainage Plan — Not submitted for our review. Zlnner Zeman Associates. Inc. 19231 — 36'" Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771— 3304 J720,050500 City of Edmonds J-720 Thoresen Residence, Lot 2 of Sequoia Ridge May 5, 2000 Enclosure Page E-2 9. Grading Plan — Plan sheet "Site" by Bientz Architectural dated 11/16/99, revised 2/28/2000 shows final site grades, but not to specified detail. 10. Architectural and Structural Plans — Reviewed; Pile depth not specified adequately on sheet S-4, detail 2. 11. Affidavit of Notice of Application — Not submitted for our review. 12. Applicant/Owner Liability and Landslide Acknowledgement — Not submitted for our review. 13. Geotechnical Declaration and Statement of Risk — Reviewed; States that "design and construction plans for Lot 2 dated January 18, 2000" were reviewed. Final plans should be reviewed, and engineer should specify which civil,. structural, and architectural plans were reviewed. 14. Architect and/or Structural Engineer Declaration — Reviewed; Does not include the required statement that engineer has "incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report." 15. Applicant/Owner Covenant to Notify and Hold Harmless — Not submitted for our review. Zipper Zeman Associates. Inc. 19231 — 36d Avenue W., Suite B201 Lynnwood, Washington 98036 (425) 771 — 3304 J720,050500 Zipper Zeman Associates. Inc. Geotechnical and Environmental Consulting JUL City of Edmonds Community Services Department 250 — 5`h Avenue North Edmonds, Washington 98020 Attention:. Ms. Jeannine Graf, Building Official Subject: Geotechnical Review of June 6, 2000 Addendum Letter Proposed Thoresen Residence, Lot 2 of Sequoia Ridge 16521481h Place West Edmonds, Washington Dear Ms. Graf: J-720 July 7, 2000 STggET FILE This letter supplements our geotechnical review of building permit application documents for the referenced project dated May 5, 2000. This supplement contains our .review of supplemental information contained in the Geo Group Northwest, Inc. letter dated June 6, 2000. The plan review number for this project is 00-115. Zipper Zeman Associates, Inc. services were limited to geotechnical review for the referenced project. These review services do not include design, analysis, or engineering recommendations for the project. These review services were provided for the purpose of evaluating general conformance of the documents with City of Edmonds permit requirements. These services were provided for the exclusive use. of the City of Edmonds for specific application to the referenced project and purpose. No other warranty is expressed or implied. A summary of the submittal status, as pertaining to geotechnical information, is enclosed with this letter. This summary is essentially unchanged from our May 5 letter. After we receive additional information, particularly the grading plan to sufficient detail, additional review items may develop. Our May 5, 2000 letter recommended that.the submittal be supplemented to address the following general topics: 1. The conclusions of the report should be re-evaluated in consideration of the probable seasonal presence of perched groundwater at higher elevation than assumed. 2. "Employing all feasible _ attendant measures" to reduce the risk of earth movement requires that an engineered retaining structure be used in lieu of rockeries. 3. Excavation for the rockery west of the house will extend into the 15 foot setback. 19231 — 36" Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771— 3304 J720,070700 r. City of Edmonds J-720 ` Thoresen Residence, Lot 2 of Sequoia Ridge July 7, 2000 Page 2 4. Because the stability of the west -facing slope in question affects the foundation support, we recommend that it be analyzed in sufficient detail to confirm that static and seismic factors of safety exceed building code requirements. 5: We recommend that a numerical factor of safety be calculated for all graded areas, including the east -facing slope and areas supporting foundations. 6. The engineer should independently determine the statistical probability of earth movement within a 25-year period, the susceptibility of the risk or hazard to correction by on -site improvement, and the measures taken to mitigate the risk or hazard. 7. The engineer recommends that specific foundation pile lengths be studied after topography of the west -facing slope is better defined. We recommend that geologic conditions at depth also be better defined, and the stability of the pile -supported house be analyzed in greater detail. The 25-foot setback recommended by the engineer should be compared to criteria referenced in UBC Section 1806.5.3. The June 6; 2000. supplemental letter .by Geo Group Northwest contains supplemental information regarding all of the items listed above. Our interpretations and understanding of the supplemental information are listed below. If we have misinterpreted the Geo Group responses, they should let us know. Geo Group concludes that the perched groundwater encountered in Boring B-2 is not significant considering the limited recharge. area. We agree. 2. In our opinion, the use of engineered retaining structures should be required on the site for retaining all fills and all cuts subject to potential instability. The use of rockeries for purposes other than erosion protection of an otherwise stable cut slope does not meet the requirement for "employing all feasible attendant measures" .to reduce the risk of earth movement. The Association of Rockery Contractors guidelines enclosed with the geotechnical report state that a rockery "is not a designed or engineered system." In order to provide detailed engineering conclusions regarding the rockeries, 'a detailed grading plan should be referenced by the engineer. 3. If excavation or disturbance of vegetation in the 15-foot setback from top of slope is not permitted, the grading plan for the back yard should be revised. 4. Our comment regarding the west -facing slope has not been addressed. The engineer should evaluate all required information for stability evaluation of this slope. Such information includes soil types and properties, groundwater conditions, topography, previous slide activity, and vegetation. The presence of seepage, areas of recent sloughing, and small slumps were reported on the steep west -facing slope. Zipper Zeman Associates. Inc. 19231— 36'" Avenue W., Suite B201 Lynnwood, Washington 98636 (425) 771— 3304 J720,070700 City of Edmonds J-720 Thoresen Residence, Lot 2 of Sequoia Ridge July 7, 2000 Page 3 5. The engineer indicates that a factor of safety exceeding 2 has been calculated for all graded areas of the site. The detailed grading plan required for permit submittal should be provided to us for review. 6. We don't understand how the engineer can comment on stability of the west -facing slope without evaluating topography or geologic conditions on the entire vertical height of the slope. 7. The engineer originally recommended, in the EIS documents and the geotechnical report, that specific geotechnical recommendations for pile lengths be further studied after the topography. of the steep west -facing slope is better defined. There has been no better definition that we are aware of. Conformance with UBC 1806.5.3 can not be evaluated with the information presented. The engineer has misinterpreted the provisions of UBC 1806:5.3; the UBC setback of H/3 or 40 feet maximum is measured from a 1H:1V plane extended up from the toe of slope, for slopes steeper than IH:1V. In order to vary from the standard UBC setback, we recommend that the applicant be required to demonstrate an adequate factor of safety for the foundations. We appreciate the opportunity to have provided this review. Please feel free to call if you have any questions or need additional information. Respectfully submitted, Zipper Zeman Associates, John E. Zippe President Enclosure: Summary of Submittal Status: July 7, 2000 rgPIRES _1 / a4 0I Zipper Zeman Associates. Inc. - 19231 — 36d' Avenue W., Suite B201 Lynnwood, Washington 98036 (425) 771 — 3304 J720,070700 City of Edmonds J-720 Thoresen Residence, Lot 2 of Sequoia Ridge July .7, 2000 Enclosure Page E-1 . Proposed Thoresen Residence, Lot 2 of Sequoia Ridge Summary of Submittal Status 16521 48"' Place West Edmonds, Washington Ordinance No. 2661 of the City of Edmonds, dated January 27, 1988 and revised February 29, 1988 contains requirements for design, geotechnical analysis, construction, and permit submittal within the Meadowdale Slide area of Edmonds. Paragraph 19.05.000 of the ordinance defines the purpose of the ordinance. Paragraph 19.05.030 describes required application submissions. The following sections of this summary contain our conclusions regarding the submittals received by our office for this project, including conformance with the required application submissions noted in the ordinance. Additionally, this summary comments on conformance with Paragraph 19.05.050 of the ordinance, which describes disclosures, declarations, covenants, and waivers required for construction in the Meadowdale Slide area. The site evaluation checklist utilized for this review is titled "Meadowdale Earth Subsidence Landslide Hazard Area Checklist for Permit Submittal" and appears to be dated May 1999. The status of the submitted geotechnical report by Geo Group Northwest, Inc. dated February 29, 2000 is summarized below: The following submittals are required by the referenced ordinance: Critical areas determination — Not submitted for our review. Lead design professional designation and statement — Reviewed; Does not include the required statement that engineer has "incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report." 3. Vicinity Map -Complete. 4. Topographic Map — Reviewed; Does not show topography of west -facing slope on subject property. Does not show locations of "known landslide masses or debris flows on or near the site which could threaten proposed structures within 100 feet." Page 6 of the geotechnical report notes that evidence of recent sliding was present on the steep slope in the west part of lots 2 and 3. Environmental Checklist — Complete; also reviewed EIS. 6. Land Clearing/Tree Cutting Plan — Plan sheet "Site" by Bientz Architectural dated 11/16/99, revised 2/28/2000 shows tree locations. A Land/Clearing Tree Cutting plan of the specified detail was not submitted for our review. Given the nature of the site, we recommend that a detailed clearing/TESC plan be submitted and reviewed. Geotechnical Report — The geotechnical report is required to discuss all items within the referenced checklist and to make specific recommendations, as listed in the "Geotechnical Report Guidelines" dated May 1999 by the City of Edmonds. Our comments regarding the geotechnical report are contained in our letter dated May 5, 2000 and supplemental letter dated July 7, 2000. 8. Drainage Plan — Not submitted for our review. Zipper Zeman Associates, Inc. 19231 — 36t° Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771 — 3304 J720,070700 City of Edmonds " Thoresen Residence, Lot 2 of Sequoia Ridge Enclosure J-720 July 7, 2000 Page E-2 9. Grading Plan — Plan sheet "Site" by Bientz Architectural dated 11/16/99, revised 2/28/2000 shows final site grades, but not to specified detail: 10. Architectural and Structural Plans — Reviewed; Pile depth not specified adequately on sheet S-4, detail 2. 11. Affidavit of Notice of Application — Not submitted for our review. 12. Applicant/Owner Liability and Landslide Acknowledgement — Not submitted for our review. 13. Geotechnical Declaration and Statement of Risk — Reviewed; States that "design and construction plans for Lot 2 dated January 18, 2000" were reviewed. Final plans should be reviewed, and engineer should specify which civil, structural, and architectural plans were reviewed. 14. Architect and/or Structural Engineer Declaration— Reviewed; Does not include the required statement that engineer has "incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report." 15. Applicant/Owner Covenant to Notify and Hold Harmless — Not submitted for our review. Zipper Zeman Associates. Inc. 19231 — 36" Avenue W., Suite B201 Lynnwood, Washington 98036 J720,070700 (425) 771 — 3304 v� (95In Group Northwest, Inc Geotechnical Engineers, Geologists • &Environmental Scientists s s.. STRLL- FILE June 6, 2000 RECEIVED G-1061-1 JUN 16 2000 Mr. Greg Guillen DEVELOPMENT SERVICES CTR. CE Engineering CITY OF EDMONDS 111 Main Street, Suite 106 Edmonds, WA 98020 Subject: Addendum Letter / Response to Geotechnical Review Proposed Thoreson Residence, Lot 2 of Sequoia Ridge Edmonds, Washington Plan Review Number: 00-115 Dear Mr. Guillen: The purpose of this letter is to respond to the Geotechnical Review by Zipper Zeman Associates, Inc. for the subject development of the Thoreson Residence. The geotechnical review comments were summarized in a letter by Zipper Zeman Associates, Inc dated May 5, 2000. We have listed each of the reviewer's comments below and prepared the following responses. In several instances we have referenced reports by others. A list of the cited references is attached to this letter. 1. Comment: The engineer interprets the depth to groundwater as greater than 30 feet on Lot 2, although Boring B-2 encountered seepage in the upper 2 or 3 feet during May 1999. The conclusions of the report, including stability of the west -facing slope, driveway cut and east -facing slope, should be re-evaluated in consideration of the probable seasonal presence of perched groundwater at higher elevation than assumed. Geo Group Northwest, Inc. 13240 NE 20th Street, Suite 12 • Bellevue, Washington 98005 Phone 425/649-8757 • FAX 425/649-8758 June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 2 1. Response: We refer to the presence of a small amount of seepage in our report as "A very thin zone of wet soil (about I foot thick) was noted in the surficial weathered soils on top of the very dense glacial till in the boring on Lot 2" (Geo Group Northwest, 2000, pg 6). The area in question has very limited recharge potential due to the fact that it is located on a ridge. It is our experience that in general, small seepage zones or areas of particularly wet soil may develop at the contact point between weathered and un-weathered glacially derived soil types as a result of the changing silt content and density of the soil. It is our opinion that the minimal seepage zone at 2 or 3 feet below ground surface will not affect the overall stability of the west -facing slope, driveway cut, or east -facing slope. The erosion associated with excavating the driveway cut shall be further minimized by the construction of a rockery which will provide permanent erosion protection. 2. Comment: In general, we are of the opinion that the City of Edmonds requirement that "employing all feasible attendant measures" to reduce the risk of earth movement requires that an engineered retaining structure be used in lieu of rockeries. The engineer should re-evaluate the use of tiered rockeries, and rockeries in the height range proposed. 2. Response: It is our opinion that the proposed construction of rockeries at the site are not for earth retaining purposes, but is a "feasible attendant measure" to reduce the risk of erosion potential and surficial soil sloughing at the driveway cut locations on the east facing slope. In order to further reduce the risk of earth movement, the 12 foot high rockeries with some fill will be reinforced by installing geo-grid and compacting all fill to structural fill specifications. It is our opinion that the proposed rockery sections, including the tiered rockeries and driveway access road on the east - facing slope, have a factor of safety equal to 2. In general, the site soils at the rockery locations Geo Group Northwest, Inc. June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 3 consist of loose to medium dense silty sands to a depth of 4 feet. Accordingly, it is our opinion that the site soils may be susceptible to surficial sloughing and erosion. The installation of rockeries will provide protection from erosion and mitigate some of the risk of surficial sloughing on the steep slopes. 3. Comment: The plans seem to indicate that a rockery will be constructed west of the house at the "15 foot undisturbed area line". We expect that excavation for the rockery will extend into the 15 foot setback. The engineer should provide criteria to avoid disturbance in this area. 3. Response: We understand that the excavation for the rockery to be constructed at the "15 foot undisturbed area line" may extend no more than one to two feet into the 15 foot setback from the top of the west -facing slope. We recommend that the following measures be taken to avoid disturbance in this area: • Vegetation removal within the 15 foot setback area should be minimized; • The location of all temporary stockpiles, excavating equipment (trackhoes and backhoes), and rockery rocks shall be to the east of the 15 foot setback line; • All exposed soils shall be covered with visqueen during rain events; • The rockery shall be constructed in accordance with Association of Rockery Contractor's construction guidelines. 4. Comment: Geologic mapping of the west -facing slope would be a reasonable means of providing a geologic cross-section for stability evaluations. The subsurface profile B-B' in the geotechnical report does not accurately reflect the planned setback and grading. Because the stability of the slope in Geo Group Northwest, Inc. June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 4 question affects the foundation support, we recommend that it be analyzed in sufficient detail to confirm that static and seismic factors of safety exceed building code requirements. 4. Response: The subsurface profile B-B' in our report shows locations of the planned setbacks and grading based upon the preliminary site planning. Based upon our understanding of the project the only addition to the B-B' profile is a level grade for the western yard of lot 2 (except for the `undisturbed area') and rockery as described above in #3. We have not been provided with detailed topography of the west -facing slope. Consequently, we have performed our slope stability evaluations of the west -facing slope based in general on the "Generalized Geologic Cross -Section and Topography" provided by the Terra Associates report for the Lorian Woods property to the west of the project site (Terra, 1989). We have analyzed the slope stability of the west -facing slope with regards to the foundation support for each of the lots, and determined that the pile supported foundations on lots 1,2, and 3 and the spread footing foundations on lot 4 will bear on the dense site soils far enough away from the steep slopes that the probability of sloughing and subsequent undermining of the building foundations is very low. Because the buildings on lots 1, 2, and 3 will be supported on piles embedded 25 feet into the dense site soils, it is our opinion that there is very little, if any increased risk, of surficial sloughing or erosion on the steep slopes as a result of the new buildings. In our geotechnical report for the site we have provided recommendations based upon our understanding of the static and seismic soil conditions at the site. It is our opinion that the static and seismic factors of safety with regard to foundation support exceed building code requirements. 5. Comment: Similar stability evaluations are recommended for the east -facing slope. We recommend that a numerical factor of safety be calculated for all graded areas, and areas supporting foundations. Geo Group Northwest, Inc. June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 5 5. Response: Our analysis indicates that all graded areas and proposed rockeries at the project site will have a factor of safety equal to 2. It is our opinion that factor of safety calculations for the foundation areas near the east -facing slope are not necessary as the buildings on lots 2, 3, and 4 will be supported on deep foundations. The residence at lot 1 will be supported on a spread footing foundation which will bear on the dense site soils. Consequently, it is our opinion that the factors of safety for all foundation areas exceed 2. 6. Comment: The engineer seems to base his conclusions regarding stability on the probabilities described in the GeoEngineers report and predecessor report. It is our interpretation of the City's requirements that the engineer should independently determine the statistical probability of earth movement within a 25-year period, the susceptibility of the risk or hazard to correction by on -site improvement, and the measures taken to mitigate the risk or hazard. We recommend that the City determine whether this requires the property owner to mitigate the risk posed by the west -facing slope to downslope property. 6. Response: We used established and accepted criteria of risk for the Meadowdale area. We agree with the existing study in that the proposed building areas have not moved in the past, and that the slight risk is due to possible erosion and surficial sloughing. Therefore an estimate that a very site specific determination of earth movement probability is not appropriate at this time. We have used our site exploration as a verification that the geologic conditions at the project site are similar to those found in the previous studies, by GeoEngineers and others. Our subsurface exploration of the project site verifies that the surficial soils at the site are susceptible to sloughing and small scale surficial movement and that deeper movements are much less likely as a result of Geo Group Northwest, Inc. June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 6 the dense condition of the glacially over -ridden soils. Accordingly, we agree with the probabilities of earth movement which others have determined. According to the geotechnical reports by RLA (RLA, 1979) and GeoEngineers (GeoEngineers, 1985), the steep slopes along the southwest part of the proposed project site have a 5 percent probability of failure within 25 years, and the slopes in the north and northeast part of the site have a 2 percent probability of failing within 25 years. The reports characterize the landslide risk in the west part of the site as involving slumps of material that has not previously failed. The landslide risk in the north and northeast parts of the site are characterized as debris slides in material that has not previously failed. The report by RLA (RLA, 1979) and to a lesser extent the report by GeoEngineers (GeoEngineers, 1985) provide recommendations and opinions regarding the overall susceptibility of risk reduction by site improvements. Based upon our exploration at the project site we concur with their recommendations that the most economically feasible and practically efficient way of lowering the risk of slope failure is to continue maintenance of existing drainage facilities in the Meadowdale Landslide Area and promote the installation of stormwater and sanitary sewer drainage systems with new development. Properly maintained stormwater and sanitary sewer drainage systems installed within the landslide hazard area can provide the advantageous effect of limiting the groundwater recharge within the landslide area. It is our opinion that lowering of the groundwater table on the project site will provide an increase in the stability of the slopes and a decrease in the risk of slope failure, at the project site. We understand that the site development plans include the addition of stormwater and sanitary sewer drainage systems in the roadway access areas. In order to further mitigate slope stability risks at the project site, we recommend that the footing, basement wall, and roof downspout drain lines be tightlined to the stormwater collection system. Geo Group Northwest, Inc. June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 7 7. Comment: The engineer recommends that specific foundation pile lengths be studied after topography of the west -facing slope is better defined. We recommend that geologic conditions at depth also be better defined, and the stability of the pile -supported house be analyzed in greater detail. The 25- foot setback recommended by the engineer should be compared to criteria referenced in UBC Section 1806.5.3. 7. Response: We have evaluated the pile foundation lengths based upon the "Generalized Geologic Cross - Section and Topography" provided in the Terra Associates report (Terra, 1989). It is our opinion, that the minimum pile foundation lengths of 25 feet into the dense native soils as recommended in our geotechnical report is sufficient to allow for adequate slope confinement of the building foundations. The UBC Section 1806.5.3 indicates that the setback for buildings at the top of a slope where the slope is steeper than 1H:1V may be measured from an imaginary plane 45 degrees to the horizontal projected upward from the base of the slope. Using the generalized topography of the west facing slope provided by the Terra Associates report (Terra, 1989) we have verified that the 25 foot setback for lot 2, 15 foot setback for lot 3 and 4, and 50 foot setback for lot 1 are within the acceptable setback requirements specified by the UBC. If you have any questions regarding this letter, please feel free to call us. Geo Group Northwest, Inc. June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 8 Respectfully Submitted Geo Group Northwest, Inc. oz&- C.,— �471 William Chang, P.E. Principal ti1NM C� x 20114 cc: Mr. John Thoreson - Sequoia Ridge Partners } IMPM3 21191 Zd0 z Geo Group Northwest, Inc. June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 9 References GeoEngineers, 1985, Report of Geotechnical Consultation, Property Value Appraisals and Assessments, Meadowdale Landslide Area, Edmonds, Washington, GeoEngineers, Inc., for City of Edmonds, February 28, 1985. Geo Group Northwest, 2000, Geotechnical Engineering Study, Sequoia Ridge Short Subdivision Edmonds, Washington, Geo Group Northwest, Inc., February 29, 2000. RLA, 1979, Final Report, Landslide Hazards Investigation, Meadowdale Area Edmonds Washington, Roger Lowe Associates, Inc., for the City of Edmonds, October 16, 1979. Terra, 1989, Geotechnical Report, Meadowdale Beach, Lots 54 to 57 Edmonds Washington, Terra Associates, Inc., June 6, 1989. Geo Group Northwest, Inc. Copy -STREET FIL RE CEIVED J U L „zoo July 14, 2000 PERMIT COUNTER entp TO: City of Edmonds Building Departm FROM: John E. Thoresen RE: permit # 00-11 I would request a variance for the driveway construction of my home for a portion of the driveway. To ease the "hinge" effect entering the garage, the architect has proposed a portion of the driveway be built at 19% grade with the remainder at 7%. 1 have enclosed a driveway section to illustrate. Thank you. 1 5ARA&E 264.00' _-. IFA i40ih Avenue Nat mt Sults 200 eeElevee, Weswnpa 00005 (425)146-MS Fs (425) 562-M Ib`-O.. 3^ -7% BLOPE Driveway Section The Thoresen Family Lot 2 Sequoia Ridge Scale: 114"=1 t-0" July 12, 2000 15% SLOP:: y O: v r A O. O CITY OF EDMONDS 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 • FAX (425) 771-0221 Website: www.d.edmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT 189p Planning • Building • Engineering March 13, 2003 John Thoreson Sequoia Ridge Partners 15621 48th Place West Edmonds, WA 98026 GARY HAAKENSON MAYOR RE: Sanitary Sewer Manholes Installed with Sequoia Ridge Subdivision Development This letter is being sent as a follow up to our phone conversation on February 21, 2003. It has been brought to our attention that the sanitary sewer manholes installed with the Sequoia Ridge Subdivision were not channeled, as required per City standards. Sewage debris is not flowing properly into the City's sanitary sewer system and is clogging in the base of the manholes. I also informed you that the debris in the manholes could not be released into the sewer system at one time as this would likely cause a pump failure at the City's lift station. Per our conversation you were going to contact a company to vactor out and properly channel the manholes. To date the Engineering division has not received notification that these corrections have been made or that a schedule for repair has been established. Please contact an Engineering Inspector so that the City is aware of any progress being made. Channeling of all manholes must be completed and inspected by April 11, 2003 to prevent Code Enforcement action. You may contact Danielle Gilbert or myself with any questions you may have at 425-771-0220 or call the Engineering Inspection line to schedule an inspection of the repairs at 425-771-0220, ext 1326. Thank you, 0 Alt '.. a� Jeanie McConnell Engineering Technician ✓c: Street File I lillb Iva Alt"A Jim Waite Incorporated August 11, 1890 • I il RETURN ADDRESS: City of Edmonds, City Clerk 121 5th Avenue North Edmonds, WA 98020 L-1 CONFORMED COPY ' 200106040088 06/04/2001 10:05 AM Snohomish P.0004 RECORDED County COVENANT OF NOTIFICATION AND INDEMNIFICATION/HOLD HARMLESS Reference #: AA-lawk Ede //5 Grantoe(s): (1) ljofleyw (2) 7J�/�,�� .�� Additional on pg. Grantee(s): City of Edmonds - Legal Description (abbreviated): Sec—y--TwAA Z/ Rng- —.Qtr lti% OR Lot c Block Plat& u ; Assessor's Tax Parcel ID#(s): (1) (2) -57✓� ��+/ __ _Assessor's Tax Parcel ID#not yet assigned CITY OF EDMONDS APPROVED FOR RECORDING BY:-&1�6— DATE: J °% PAGE L OF Under the review procedures established pursuant to the State Building Code, incorporating amendments promulgated by the City of Edmonds, and as a prerequisite to the issuance of a building permit for the construction of a residential structure and attendant facilities, the undersigned OWNERS of property do hereby covenant, stipulate and promise. as follows: E :___oF OVED FOR RECORD G: �DATE:' 1. Description of Subject Property This covenant of notification and indemnification/hold harmless relates to a tract of land at the street address of %C //9 *7Zi rd Aw. Wey- (insert street address), Edmonds Snohomish County, Washington and legally described as: r SAfWY M 1?106e7 2. Notification and Coven ant* of Notification The above referenced site (hereinafter "subject site") lies within an area which has been identified by the.City of Edmonds as having a potential for earth subsidence or landslide hazard. The risks associated with development of the site have been evaluated by technical. consultants and engineers engaged by the applicant as a part of the process to obtain a building permit for the subject site.. The results of the consultant's reports and evaluations of the risks as with development are contained in building permit file number (insert number) on file with the City of Edmonds Building Department.. Conditions, limitations, or prohibitions on development may have been imposed in accordance with the recommendations -of ,, APPROVED FOR RECORDING: BY: DATE: PAGE OF -1 the consultants in the course of permit issuance: The conditions, limitations, or prohibitions may require ongoing maintenance on the part of any owner or lessee or may require modifications to the structures and earth stabilization matters in order to address future or anticipated changes in soil or other site conditions. The statements and conditions b the proposed. Y O K'NERS' geotechnical engineer, geologist, architect and/or structural engineer are hereby incorporated by reference from the contents of the file as fully as if herein set forth. Any future purchaser, lessee, lender or any other person acquiring or seeking to acquire an interest in the property is put on notice of the existence of the content of the file and the City urges review of its contents. The file may be reviewed duHna , -1 L___ copies obtained at the Building Department, City of Edmonds, 121 5th Avenue North, Edmonds, Washington 98020. 3. Indemnification and Hold Harmless The undersigned OWNERS hereby waive any and all liability associated with development, stating that they have fully informed themselves of all risks associated with development of the property and do therefore waive and relinquish any and all causes of action against the City of Edmonds, its officers, agents and employees arising from and out of such development. In addition, the OWNERS on behalf of themselves, their successors in interest, heirs and assignees, do hereby promise to indemnify and hold harmless the City of Edmonds, its officers, agents and employees from any loss, claim, Iiability or damage of any hind or nature to persons or property either on or off the site resulting from or out of earth subsidence or landslide hazard, arising from or out of the issuance of any permit(s) authorizing development of the site, or occurring or DONE this • o APPR4DLOR RECO IN : BY:ATE:..? dl�/p/ PAGE OF day of G ZD o 0 OWNER(S) By: By STATE OF WASHINGTON ) ss: COUNTY OF 'I certify that I know or have satisfactory evidence that CD k) signed this instrument and acknowledged it to be (his/her) free and voluntary act for the purposes mentioned in this instrument. DATED this day of ' �, Q� , / y ao�'®p�� n NOT PUBLIC _ G�(SC r `� : My commission expires: -- CU — D a06600 e p �SHtNG�0�s,�. a°Beet+a,e,e°A L:%TEMP\BUILDINGIMEADOVACOVENANT • L] RETURN ADDRESS: City of Edmonds, City Clerk 121 5th Ave North Edmonds, WA 98020 a �Snohomish o,00;�200107020149 Ea a1o�v P. ooE COVENANT TO NOTIFY, MAINTAIN AND MONITOR Dwelling Fire Sprinkler System Reference #:�� , Grantor(s): (1) �l�=N�► )E.-ri4oke-se;,g (2) cltf�( Additional on pg. Grantee(s): City of Edmonds Legal Description (abbreviated): Sec Twn Rng Qtr OR Lott Block Plat SEG> uui st �� Assessor's Tax Parcel ID#(s): (1) 005 13 1 a � 30() (2) Assessor's Tax Parcel ED# not yet assigned AUTHORIZED FOR RECORDING ity of Edmonds By: Date: 01 Page I of WHEREAS, the undersigned owner of real property located within the City of Edmonds, Washington, has requested a modification of the strict requirements of the Uniform Fire Code, Uniform Building Code and Edmonds Community Development Code related to the sizing and spacing of water mains and/or fire hydrants, WHEREAS, pursuant to modification authority established by state building code, state fire code and City ordinance, installation of a fire protection system in accordance with the provisions of the NFPA 13D, Standard for Installation of Sprinkler Systems in One- and Two -Family Dwellings, has been approved for installation (hereinafter "additional system") pursuant to the requirements of City of Edmonds Building Department Plan Check #01-194; and WHEREAS, an order to obtain a building permit, the undersigned owner of real property has warranted, promised and covenanted to undertake certain actions in order to maintain said additional system; NOW, THEREFORE, Mr. John Thoresen, does hereby warrant, covenant, stipulate and promise, on behalf of themselves and all future owners, successors.and assigns, of the herein described real property (hereinafter "Owners") to undertake the following action in consideration of the enhanced value of their property by its development, and by the approval of a modification of the strict provisions of the NFPA, Uniform Building Code, Uniform Fire Code, and the ordinances of the City of Edmonds pursuant to the aforementioned file number. RECORDER'S NOTE: PORTIONS OF THIS DOCUMENT ARE POOR QUALITY FOR SCANNING. RECEIVEM J U L 3 1 2001 EDMONDS CITY CLERK 1. Burdened Tract. The undersigned owners are owners of a certain tract of land located in the City of Edmonds at the street address of 16118 72"d Avenue West, Edmonds, Washington. The Burdened Tract is legally described on the attached Exhibit "A", incorporated by this reference fully as if herein set forth. 2. Development of Land. The owners stipulate that they have benefited in terms of the value and development potential of their property by the approval of the modification of the strict provisions of the building codes, fire codes and City ordinance. Accordingly, the provisions contained herein touch and concern the land, and shall run with aforementioned Burdened Tract, and combine all future owners of said tract. 3. Undertakings of Owners. The owners warrant, covenant and promise that: 3.1 He/she/they will notify all future property owners, both individually and by recording of this Covenant in the land records in Snohomish County, Washington, of the obligations contained herein, and in City of Edmonds Building Department Plan Check #01-194. 3.2 Pursuant to said City file, alternative methods of providing for the life and safety of the occupants of structures built upon said Burdened Tract have been approved. Said modifications depend on and require, for the safety of such residents, that they be continuously monitored, inspected, updated, replaced, or otherwise maintained in accordance with provisions of NFPA 13D, Standard for Installation of Sprinkler Systems in One- and Two -Family Dwellings,. The owner, on behalf of themselves, their agents, assessors and assigns, promise to inspect, maintain, monitor and periodically test any sprinkler system or other modified fire safety requirement referenced herein or in the City file, incorporated by this reference as fully herein set forth, in accord with the requirements of the Uniform Fire Code and the National Fire Protection Agency (NFPA) 13D, Standard for Installation of Sprinkler Systems in One- and Two -Family Dwellings, 1999 Edition, as well as the manufacturer's recommendations. In the event that the additional system fails or otherwise requires repair or replacement, the Owners shall immediately undertake said actions. 3.3 All costs of this periodic maintenance, inspection, testing, replacement, reconstruction or any other act necessary to maintain the system as modified in accordance with said NFPA and the manufacturer's recommendations, shall be at the expense of the owner or successors in interest in the burden tract. 3.4 The owners, on behalf of themselves and their successors in interest, agents and assigns, hereby understand and acknowledge that their failure to maintain, monitor and periodically test, and if necessary, replace, reinstall or rebuild said additional system, shall result in loss of occupancy permit for any building or structure constructed on the Burdened Tract which is not continually maintained, inspected and monitored re repaired, replaced or rebuilt, in accordance with the provisions of the NFPA, City ordinance, Uniform Fire Code and Uniform Building Code and the manufacturer's recommendations. AUTHORIZED FOR RECORDING ity of Edmonds By; Date: Page of DONE THIS DAY OF c�-e , 2001. % 1 0 STATE OF WASHINGTON ) ) ss. County of`� jeM-•.r I certify that I know or have satisfactory evidence that L'56&6Q0G 77/oP,6-s l is the person who appeared before me, and said person acknowledged that he signed this instrument and acknowledged it to be his free and voluntary act for the uses and purposes mentioned in the instrument. DATED: CQ Itq f o NOTARY PUBLIC in antl for the giate of Washington, Residing in My commission expires --C3 1lrTq` �. a j�4 C By: . o� .•• " °.,,,,t.,,,,••• WIFE ,. 0 STATE OF WASHINGTON ) ) ss. County of I certify that I know or have satisfactory evidence that 66/ 6eVG i,�,ec:sVt/ is the person who appeared before me, and said person acknowledged that she signed this instrument and acknowledged it to be her free and voluntary act for the uses and purposes mentioned in the instrument. DATED: (-a Cry NOTARY PUBLIC in and for the State of Washington, Residing in My commission expires --1�0 —� STATE OF WASHINGTON ) )ss County of On this day of , to me known to +�ejeeeeeeeeee°♦t .y ms Co 2001, before me personally appears be the and acknowledged said voluntary act and deed of said corporation, for the and on oath stated that instrument. of instrument to be the free and uses and purposes therein mentioned, is authorized to execute said SUBSCRIBED AND SWORN TO before me this day of , 2001. NOTARY PUBLIC in and for the State of Washington, Residing in My commission expires AUTHORIZED FOR .RECORDING ity of Edmonds By: Date: �P Page *3!— of EXHIBIT "A" LEGAL DESCRIPTION PARCEL A: ORDER NO. 133866-4 LOT 2 OF SHORT PLAT RECORDED UNDER RECORDED UNDER RECORDING NUMBER 200009145003, BEING A PORTION OF LOT 53 AND THE NORTH HALF OF LOT 52 OF. PLAT OF MSADOWDALE BEACH, ACCORDING TO PLAT RECORDED IN VOLUME 5 OF PLATS AT PAGE(S) 38, IN SNOHOMISH COUNTY, WASHINGTON. PARCEL B: AN EASEMENT FOR INGRESS, EGRESS AND UNDERGROUND UTILITY PURPOSES OVER, UNDER AND ACROSS THE FOLLOWING DESCRIBED PROPERTY: ALL THAT PORTION OF THE SOUTH HALF OF LOT 52 AND THE EAST 120 FEET OF LOT 57, PLAT OF MEADOWDALE BEACH, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 5 OF PLATS, PAGE 38, RECORDS OF SNOHoNffSR COUNTY, WASHINGTON, ALSO KNOWN AS LOT A OF THE CITY OF EDMONDS LLA S-27-90, RECORDED UNDER SNOHOMISH COUNTY AUDITOR'S RECORDING NO. 9107030640, MORE PARTICULARLY DESCRIBED AS FOLLOWS: BEGIIINING AT THE SOUTHEAST CORNER OF SAID LOT A; THENCE NORTH 89038'04" WEST ALONG THE SOUTH LINE THEREOF A DISTANCE OF 20.00 FEET; THENCE LEAVING SAID LINE NORTH 36044'52" WEST A DISTANCE OF 133.63 FEET TO A POINT ON THE NORTH LINE OF SAID LOT A; THENCE SOUTH 68003'03" EAST ALONG SAID NORTH LINE A DISTANCE OF 45.00 FEET; THENCE LEAVING SAID LINE SOUTH 43023' 14 EAST A DISTANCE OF 40.86 FEET; THENCE SOUTH 33°49' 13" EAST A DISTANCE OF 55.00 FEET TO A POINT ON THE EAST LINE OF SAID LOT A; THENCE SOUTH 01047'58" WEST ALONG SAID LINE_A DISTANCE OF 15.00 FEET TO THE POINT OF BEGINNING. ... 5 . f'i 1 .. �., •y.. , . . .. • p • ti V : t•1 ... �.+►::'.�11. Ji341G:4��7fL':9•:y.9nw• •^ '.: .. Inc.1oll CITY OF EDMONDS 121 5TH AVENUE NORTH • EDMONDS, WA98020 • (425) 771-0220 • FAX (425) 771-0221 Website: wwwxi.edmonds.wa.us DEVELOPMENT SERVICES DEPARTMENT Planning • Building • Engineering February 23, 2005 John E. Thoreson 16118 72nd Avenue West Edmonds WA 98026 Re: Meadowdale Drainage Improvements Dear Mr. Thoreson: GARY HAAKENSON MAYOR We are in receipt of your letter of February 14, 2005 to Jeannine Graf. Please note that we are in disagreement regarding many of the assertions contained in your letter. First, the City's Meadowdale drainage improvements are designed to protect the public right of way and the City's sewer improvements in the area. They are not now nor have they ever been designed to protect individual private properties. The dewatering of the Meadowdale landslide mass has had a positive impact on the overall probability of earth movement in the area. The particular drainage improvement„ that you refer to are on the lower third or quarter of t.,e steep slope and provide additional stability to downslope areas by dewatering the hillside. The improvements were neither designed nor intended to stabilize the upslope portion of the property. Secondly, the City has investigated reports of slides at this specific site since 2001. Repeated investigations have been performed for the City by its geotechnical experts, Landau Associates. Those reports have consistently found that the slide at the top of the slope is unrelated to the City's drainage improvements or their maintenance. The reports provided to the City indicate that the landslide activity which has occurred was most likely caused by inclement weather as a part of the natural process of surfical earth movement in that area. In a nutshell, the slope is in the naturalprocessof retreat. Subsequent slides have occurred along cracks relating to the initial slide. As: you know, there were questionable construction practices at the Bosch site in 2001 which may or may not have contributed to the earth movement. The geotechnical reports provided by Landau Associates and others. do not support the assertion you make in your letter that the slope is failing from the bottom up. The City has documented the successive slides both through photographs and through the reports of its consultant. That information clearly indicates that the slides are occurring from the top down due to inclement weather and the natural process of slope retreat at that location. (wss593941.DOC;1/00006.900000/) • Incorporated August 11, 1890 • John E. Thoreson February 23, 2005 Page 2 Next, it is correct that the City has ceased to maintain the specific drainage improvement referenced in your letter. Maintenance was suspended in December of 2001, when debris from tree topping blocked access. The City ceased maintenance activity altogether on March 6, 2002, because the hillside was unsafe for maintenance workers. There was no safe way to maintain that portion of the improvement. It is also highly probable that the improvement was damaged during the course of the slides. Review of the line by a TV monitor indicated that it was distorted in shape and blocked by debris. Because of the instability of the slope, the City has not attempted to maintain or repair that catch basin and piping, but rather initiated a process to replace it with another improvement. On October 25, 2002, R.W. Beck was commissioned to design a new improvement. On August 26, 2003, the City awarded a construction contract, and on September 10, 2003, a preconstruction meeting was held with the contractor. On September 16, 2003, immediately prior to the date on which work was to commence under this contract, a new slide occurred above the area where the work was to be done, again rendering the site unsafe for construction workers to work in the area. Accordingly, that contract was terminated. The City is currently in the process of redesigning the improvement. The improvement, however, will be located at the bottom of the slope and is intended to catch`the seepage from the hillside at a location which continues to serve its purpose -- protection of the City's sanitary sewers and public right of way. The improvement will be located where it can be safely maintained given the ongoing instability of the hillside behind it. You assert that the developer of Lorian Woods - presumably Dr. Robert Anderson, has indicated to the City that catch basins and related drain pipes have been removed and not replaced. I have no record of any such communication. Finally, the City will continue to maintain its improvements, in this case through replacement. There are no plans to extend the City's storm drainage system in this area. Sincerely, DUANE V. BOWMAN Development Services Director cc: Phil Holroyd John Johnston Jim Bosch ( WSS593941.DOC;1 /00006.900000/) r P_ 02 GF.O Group Northwest, Inc. October 8, 2001 CITY OF EDMONDS Attn: Ms. Jeannine Graf 121 5 ' Avenue North Edmonds, WA 98020 Subject: Geotechnical Special Inspections - Revised Final Report Sequoia Ridge Development Lot 2, Thoresen Residence 16118 72"d Avenue West, Edmonds, WA Dear Ms. Graf. Geotechnical Engineers, Geologists & Environmental Scientists Project No. G-1061A Geo Group Northwest, Inc., has completed the geotechnical special inspections for the Thoresen Residence at 16118 72"d Avenue West, in Edmonds, WA. Geo Group Northwest periodically monitored construction activities for the following items: • Temporary cut slopes • Installation of concrete piles for the foundation • Rockery wall installation, backfill, and drainage between Lots 1 and 2 • Basement floor slab and garage slab Based upon our professional opinion, site observations, and testing during the monitoring of the construction, the completed development substantially complies with the recommendations in the geotechnical report and with all geotechnical related permit requirements. If you have any questions, please call. Sincerely, GEO GROUP NORTHWEST, INC. Wade J. Lassey Engineering Geologist William Chang, P.E. Principal ti11�►M C�rq Z r~/co."r1AwhW. -off ?;11� �mNA <—t RECEIVED c�UtWAL� .. 6 2001 13UILgING DEPT. 13240 NE 20th Street, Suite 12 Bellevue, Washington 96005 Phone'425/649-8757 FAX 4251649-8758 F i t 0 u Date: To: From: Subject: MEMORANDUM BOLDING F E B / J 2001 February 8, 2001 Jeannine Graf, Building Official Jeanie McConnell, CIP Specialist'1l�� Site Grading Review, Sequoia Ridge- Plat 1 An on site meeting was held February 1, 2001 with Aaron McMichael, from Associated Earth Sciences, John Thoreson, Jeff Shaye, Lyle Chrisman, and myself to review the erosion measures that had been implemented in response to the initial site review by Aaron McMichael. Attached is a letter from Aaron McMichael outlining this site review and the areas of needed improvement. I have since performed two additional site inspections to determine the completeness of the requirements set forth by Associated Earth Sciences. According to Jeff Shaye, the geotextile filter fabric sacks for the catch basins are on order. As a temporary measure filter fabric has been placed in each of the. catch basin grates. The quarry spall rock has been installed along the western shoulder/ditch line of the access road, but needs to be graded to slope awa)r from the rockery. Lot 2 has not been covered with the on -site hogfuel wood chips in anticipation of the grading that will be done for the foundation. Once the grading is complete, the surrounding exposed soils are to be covered with the hogfuel wood chips. These remaining issues will be monitored during the construction of the SFR. City of Edmonds and Community Services Department G:\ENGRUeanie\Cortespondence\leannine memo -sequoia ridge.docEngineering Division r 1 Associated Earth Sciences, Inc. E D, February u, 2001 RECEWEL11 Project No. KE 00833A FEB -• 7 2001- City of Edmonds ENGINEERING DIVISIQI; Development Services Department, Engineering Division 121 Fifth Avenue North Edmonds, Washington 98020 Attention: Ms. Jeanie McConnell, CIP Specialist Subject: Site Grading Review Sequoia Ridge Plat Edmonds, Washington Ref; rence: Associated Earth Sciences, Inc. Grading Review Letter Project No. KE00833A, December 22, 2000 'Dear Ms. McConnell: As requested, an engineer from Associated Earth Sciences, Inc (AESI) met with you and th-_ property owner at the subject site on February 1, 2001. The purpose of our meeting was to observe recent compliance grading work to determine if the owner has fully implemented the temporary erosion and sedimentation control plan (TESCP)- measures recommended in the above - referenced letter. After touring the site and discussing the recommended TESCP measures with both parties, AESI recommends that the following _measures still need to be completed to bring the site into full compliance with our earlier recommendations. • The plat slopes on Lots 3 and.4 should be covered with additional straw mulch so that no soil remains exposed. • The crest of 1he graded slope at the top of Lots 3 and 4 should be provided with a soil berm to prevent surface runoff from freely flowing onto the adiacent slopes. Tile intercepted runoff should be directed into a catch basin via surface swale or ADS tightline pipe. Corporate Office • 91 ! FiRh Avenue. S:,ltc 1()0 • 1:,&land. VV., G8033 • Phone ,25 837-7701 • Fa • 115 827-5421 West Sound Office • 1 70 Hadrc•ne Lane Ho, ih E.;mbndg^ Is!and.W abl ;0 • ' •_ne 20. 780.9-70 • Fa •. 205 780.6438 i • The western shoulder/ditch line along the access road should be lined with 2- to 4- inch quarry spall rock. The rock ditch should direct collected runoff into the nearest catch basin. Check dams made of the same material should be placed every 20 feet up the ditch alignment. • The catch basins should all be provided with geotextile filter fabric silt sacks. The tarps placed on the fill slopes along the east side of the access road should be sand bagged and roped in place to prevent tarp blow off. • Lot 2 should be finished graded so that the lot ground surface drains to the southeast, away from the slopes to the north and west. The lot should then be covered with a minimum 3-inch cover depth of the on -site hogfuel wood chips. The driveway access should be covered with crushed rock. AESI has also reviewed the January 10, 2001 letter to the City by Geo Group Northwest, Inc. This letter requests that the sediment control pond planned for Lot 4, as specified in the site TESCP by David Evans and Associates, Inc., should be eliminated. It is AESI's opinion that if the recommendations presented above are completed, the sediment control pond could be eliminated without increasing site erosion hazards. However, final determination of whether this pond is necessary should be completed by David Evans and Associates. Inc. In summary, it is our opinion that further plat development and construction on Lot 2 could be completed subsequent to full implementation of current TESP criteria presented above. 'We hope this information meets your present needs. If you have any question, please call Sincerely, ASSOCIATED EARTH SCIENCES, INC. l Kirkland, Washington G. Aaron McMichael, P.E. Senior Project Engineer GAM/ap KE00833A3 D:\WP\ap\2-01 — W2K FEB: 5.2001 5:24PM DRV EVANS NU.1bb r.1 ,6 • _ DAVID EVANS AND ASSOCIATES, TELECOPY TRANSMITTAL TO: Lyle Chrisman FIRM: City of Edmonds FROM: Jack Molver DATE: February 5, 2001 FAX NO: 771 0221 PHONE NC: # OF PAGES; 1 PROS. x: THOR0001 REGARDING: Sequoia Ridge COPIES:John Thoreson FAX NO: 4240809 ORIGINAL TO FOLLOW: ❑ REGULAR MAIL ❑ OVERNIGHT MAIL ❑ COURIER i6.2e We r Marine TACW Drive, Suite�00 Licrts, Washington 98sei Td: 425•259-4099 Fax: q�5.159.3;3� ❑ NIA COMMENTS: Lyle, This message is to confirm that the temporary sediment trap shown on the TESL Plans for this project is no longer warranted, John Thoresen called me Friday February 2nd to advise me that the City geotechnical representative, Aaron McMichael of AESI, suggested that such a statement from me should be included for the record. Now that the permanent storm drainage system has been installed, grading substantially completed, and exposed soils stabilized with straw mulch, abandonment of this temporary component is appropriate. Please call me if you have any questions regarding this statement. RECEIVED FEB - 7 2001. ENGINEERING 01VISION DEC-2372000 FR 102 : 09 PM 4 F RK NU. 4i b aC i 54i'4 Associated Earth Sciences, Inc. December 22, 2000 Project No. KE00833A City of Edmonds Development Services Department 121 5'h Avenue North Edmonds, Washington 98020 Attention: Ms. Jeannine Graf Subject: Grading Review Sequoia Ridge Plat Edmonds, Washington Reference: Geo Group Northwest,' Inc. Geotechnical Engineering Report Project No. G-1061-1, February 29, 2000 David F..vans and Associates, Inc. Site Improvement flans Sequoia Ridge, Edmonds, Washington, Dated November 1999 Dear Ms. Graf: r. uc As requested, Associated Earth Sciences, Inc (AESI) has completed a review of the current Lrading work completed for the Sequoia Ridge plat. The purpose of our review was to determine if further winter graduig work on the plat could be completed during the City of Edmonds Seprernber 30 to April 30 grading moratorium, while maintaining minimum erosion control procedures per the City's development code. Further, AESI has been asked to provide an opinion concerning whether a building permit for Lot 2 should be issued during the moratorium period. Our work has included a review of the above -referenced geotechnical report and related documents prepared by "Lipper Zeman and Associates, and the City of Edmonds, including dcvelopincnt and grading regulations for the Meadowdale landslide area. AESI also made visits to the site on December 6 and 14, 2000! Our services were limited to review of the project pertaining to grading and erosion impacts to the plat and surrounding properties. Our review has not been completed to verify or support the conclusions reached by. Geo Group Northwest, Inc. or others concerning slope stability of Corperate OfFce - 911 F.hh Av!nue. SuuC 100 - K✓k'and. WA 38033 - Phcne 425 817.7701 -Fax 425 527 5424 west Sound Once - 179 Madrone lanC NCrth - Samondae Iiland.'NA 981 10 - Phone 206 780.9370 - Fax 206. 760.94: DEC-22,-2000 FK1 U2:UU FM 4 MA NU. qeo del 04eli • r. UZ) the site, or to confirm the appropriateness of the proposed building setbacks or foundation support. This report has been prepared for the exclusive use of talc City,of Edmonds, for specific nplilication to this project. Within the limitations of scope, schedule and budget, our services have been performed in accordance with generally accepted geotechnical engineering anal engineering geology principles and practices in effect in this area at the time our report was prepared. No other warranty, expressed or implied, is made. Project Description '1'lic subject _parcel consists of a partially wooded slope and ridgeline covering an area of 3.66 acres. 'f le western portion of the property is formed by a ridgeline, which slopes steeply, downward to the west at a gradient of approximately 80 to 100 percent. East of the ridgeline the site slopes steeply downward to the northeast at gradients of 30 to 60 percent. The toe of this slope is bordered by a Category 2 Strewn and North Meadowdale Road. Based on the Sequoia Midge Site Development Plans prepared by David Evans and Associates, Inc. (DEA), dated November 1999, it is our understanding that the plat consists of four lots, designated Lots 1 through 4. Lot 1 is located at the top of the parcel, while hots 2 and 3 step downslope to Lot 4, which is located adjacent to North Meadowdale Road. The site will be accessed through a driveway access road extending southward into the plat from 72tid Avenue West. Sile Ohcervations Currently, Ille plat has been cleared of forest cover and extensively graded. The grading consists of cutting a 2040ot-wide access, and utility easement road along the east slope of the ridgeline. Resulting cut slope heights range from 6 to 10 feet. Excavated material appears to have been placed as a prism of fill on the adjacent slope to level the eastern portion of the access road. These fill slopes arc inclined at approximately 1.51I:1V to lII:1V (Horizontal:Vcrtical). Soil tension cracks were noted along the top of the fill slopes,' Storm sewer manholes and catch basins, aitd portions of exposed storm sewer pipes were noted within the access road. Building, pads have been bench cut into the crest area of the ridgeline on Lots 2 and 3. A partially covered soil stockpile is located on Lot 1, directly above the adjacent cut. slope on Lot 2. Cut slopes along the west and south perimeters of the access road and portions of Lots 2 and 3 have been faced with 8- to 12-foot-high rockeries, Review of field reports -by Geo Group Northwest, inc. indicates that portions of these rockeries have been reinforced using; geogrids. The western Portion of the cut slope along the south perimeter of Lot 2 is standing near vertical and has no erosion protection. .During our visit, the slope was sloughing small blocks of soil following a freezing and thawing cycle. Sire soils were observed to consist of lodgement till (silty gravelly sand) within the upper, exposed cut slope portions of the site, and advance outwash (sand and gravel) at lower elevations. The cut slopes exposed on Lot 2 consisted of dense lodgement till. Cut and fill soils located in Ow access roadway consisted of sandy soils, likely derived from on -site advance outwasb. The slopes within the lower portion of the plat consist of lodgement till fill, or Whidbey Formation soils. i M 'DEC-22-2000 FRI 02:10 PM 4 FAX N0, 425.827 5424 r. u4 Site erosion control consists of a geotextile silt fence and ground cover mulches. The silt fence has been constructed along the base of the fill slopes, at the east margin of the cleared area, wl►ich appears to be in the general location of the wetland buffer line. Sediment eroded off the lill slopes has buried the silt fence in several locations. The lower portion of the site does not contain a sediment trap. Consequently no control of turbidity is being provided prior to release into the adjacent stream. The lower fill slopes located on Lot.4 have been mulched using a thin covering of straw. The mid -slope areas have been partially covered with wood chips generated [luring the initial clearing. Exposed soils within the upper portion of the site are being moderately eroded due to surface runoff. ('r,trr_ union and Recommeudations 'Basul on the project Plans and site conditions described above, it is AESI's opinion, that although the site is •located within the Meadowdale landslide complex, the current�work on the plat does not appear to present stability hazards to the general site or neighboring properties. llowever, site grading work currently does not meet the City of Edmonds erosion control criteria (Code Chapters 18.30, 18.45, 2O.15A), and the temporary erosion and sediment control plan (TESCP) conditions contained within the above -referenced DEA plans have not been fully implemented. Therefore, no further development work should be completed until these conditions are implemented. Please refer to Sheets 2 and 3 of the DEA plans. The plans should be revised as needed by DEA to address the conditions outlined below. Iss»anc.e of a building permit on Lot 2 would require stabilizing the, site against continuing erosion. 1•ije majority of the stabilization efforts would include providing erosion protection for the existing cut_ slope, and provision of adequate road access, site drainage, and ground surface erosion control measures. This work would need to be integrated with the plat TESCP efforts. Subsequent to addressing these issues, winter construction on Lot 2 should not negativcly impact the site. The following minimum elements should be addressed in the plat TFSCP. All TESCP measures should be completed at the site prior to further plat development. 1'lal.Lrst�ion..C�l The existing silt fence should be cleaned of sediment and rebuilt to current City standards. No gravel was noted as key material behind the silt fencing. Sediment wilich has migrated into the wetland buffer should be removed. The drainage trench behind the silt fence should be maintained to prevent flow through the silt fence. The sediment trap specified for Lot 4 should be constructed. The access road and adjacent lot areas should be backsloped to drain away from the • crest of all till slopes and the tops of all rockeries. A shallow rock -lined Swale with check clams should be provided to convey the- surface runoff to the existing catch basins. The crest of the fill slope above Lots 3 and 4 should be provided with a soil berm to prevent surface runoff from freely flowing onto the adjacent slopes. The 3 • DEC-22-2000 FR l 02:10 PM 4 FAX NO. 42b 82 ( b424 V. u5 i,Ytercepted runoff should be directed to a catch basin via surface swale or ADS t.i,htline pipe. All catch basins which receive site runoff should be provided with geotextile silt sack inserts to catch sediment. At a minimum, the sacks should be cleaned of sediment monthly and checked after each heavy rainfall event. 'l'ho fill slopes located adjaccut to the access road, soil stock piles, and exposed cut slope soils located above all rockeries should be fully tarped with plastic sheeting. The long axis of the sheeting should run up the slope and maintain at least 24 inches of lap. The tarping should be held in place with roped and staked sandbags. • The soil stockpile located on Lot 1 should be located no closer than 15 feet from the top of the adjacent rockeries. The remaining plat slopes, predominantly located on Lots 3 and 4, should be heavily mulched with additional straw or the on -site wood chips. We recommend a minimum mulch cover of 3 inches. Let.2_Cir.ading, an 1rosion Control Subsequent to implementation of the plat TLSCP, the following minimum grading and erosion conlrol conditions should be included in a TL`SCP for Lot 2, prior to issuance of a construction pi rrri i 1. The existing cut slope along the southwest perimeter of the lot should be provided with erosion protection. The most feasible means of providing permanent protection appears to be extension of the existing rockery. • The lot should be graded to direct surface runoff away from the west slope crest, and away froin the top of all rockeries. The runoff should be directed into the site catch basin system. To provide vehicle. access to the lot, the portion of the plat road leading to Lot 2, and the lot driveway should be graveled. The entire lot ground surface around the building foundation should be mulched. Runoff from the building roof should be tightlincd to the stonn sewer system as soon as the roof and gutter system is in place. 4 " DEV22=2000 FR I 02 :11 PM 4 1• AX NU, 4eb bet 54e4 r, uo. closure In sumlYlary, it is our opinion that further plat development and construction on Lot 2 could be completed subsequent to full implementation of current TESCP criteria, and modified criteria addressing the erosion control items outlined above. Review, modification, and implcnlenultion of the TESCP should be completed by DEA. The revised TF.SCP should be reviewed by our office, and on site compliance verified by a representative of the City of I:dwonds. AGSI can provide review of site compliance, if requested. Further, as construction ProE;resscs, periodic review of the TESCP should be completed by DEA. The TESCP should then be modified if necessary to maintain site stability and erosion control in compliance with C:ity of Edmonds development code. We hope this information meets your present needs. If you have any questions, please call Sincerely, ASSOCCA`1'ED EARTH SCIENCES, INC. Kirkland, Washington oN M`1 o2/ZL F' 33222 O SSInNAL �� UP I R ES 27 1,2 oa G. Aaron McMichael, P,E- Senior Project Engineer 0 u.r,wia I.D p.Ud\12-00 - WX 1 5 411° `` = CITY OF EDMONDS. 121 STH AVENUE NORTH • EDMONDS, WA 98020 - (425) 771.0220 • FAX (425) 771-0221 DEVELOPMENT SERVICES DEPARTMENT I Planning • Building • Engineering 89,11 December 22, 2000 John Thoresen Sequoia Ridge Partners 15621-481h Place West Edmonds, WA 98026 GARY HAAKENSON MAYOR SUBJECT: Sequoia Ridge Short Plat (S-00-108) — Erosion Control fED-133) Dear Mr. Thoresen, As you know, all grading/excavation work in the Meadowdale Landslide Hazard area was to have stopped by September 30, unless the geotechnical engineer of record determines work can continue. The geotech of record is required ,to inform the City of the extended work period and the provisions and limitations of that period. Because grading has occurred at the Sequoia Ridge site beyond September 30, we have had a third .party geotechnical engineer review the current grading work to determine if further winter grading on the plat could continue. Based on their review, the following erosion control items must be incorporated into your temporary erosion and sediment control plan (TESCP) and completed before further work on the plat can continue. 1. The existing silt fence must be cleaned of sediment and rebuilt to City standards and additional support stakes must be installed to better support the fence. 2. Sediment that has migrated into the wetland buffer must be removed. 3. The access road and adjacent lot areas above the rockery must be back -sloped to drain away from the crest of all fill slopes and rockeries. A shallow rock -lined Swale with check dams must be provided to convey the surface runoff to the existing catch basins. The crest of the fill slope above Lots 3 and 4 must have a soil berm installed to prevent surface runoff, and the intercepted runoff must be directed to a catch basin via surface swale or ADS tightline pipe. 4. The fill slopes located adjacent to the access road, soil stock piles and exposed cut slope soils located above all rockeries shall be fully tarped with plastic sheeting. The long axis of the sheeting must run up the slope and maintain at least 24 of lap. The tarping shall be held in place with rope and staked sand bags. 5. The soil stock pile located on Lot 1 shall not be located any closer than 15' from the top of the adjacent rockeries. 6. The remaining plat slopes, predominantly located on Lots 3 and 4, must be heavily mulched with additional straw or on -site wood chips. • Incorporated August 11, 1890 • 0iclor 1 � Y John Thoresen Sequoia Ridge Partners December 22, 2000 Page 2 / f 7. A temporary sediment pond must be constructed as shown on the approved plans. The exact location can be determined by the Engineer of record. Before we will issue the building permit for Lot 2, the following minimum grading and erosion control measures must be included in the TESCP plan for said lot, and work must be completed. 1. The existing cut slope along the southwest perimeter of the lot shall be provided with permanent erosion protection. 2. The lot shall be graded to direct surface runoff away from the west sloped crest and away from the top of all rockeries. The runoff shall be directed into the site catch basin system. 3. To provide vehicle access to the lot, the plat road and lot driveway must be graveled or provided with an asphalt treated base. 4. The entire lot ground surface around the building foundation must be mulched. 5. Runoff from the building roof must be tightlined to the storm sewer system as soon as possible. Please revise and submit your TESCP for the plat and for Lot 2 to us for review and approval. If you have any questions, please don't hesitate to contact Lyle Chrisman at 425-771-0220, Ext. 1324. Sin rely, a V. Bowman Development Services Director DVB/ALC/cmc GAENGMYLEWhorcsea-sequioa ridge.doc Geotechnical Engineers, Geologists 1 Group Northwest In & Environmental Scientists December 8, 2000 DEC 12 2000. ENGINEERING DIVISION Project No. G-1061 CITY OF EDMONDS Attn: Ms. Jeanie McConnell, CIP Specialist Development Services Department, Engineering Division 121 5 h Avenue North Edmonds, WA 98020 Subject: Wet Season Restriction Waiver Sequoia Ridge Development Edmonds, WA Ref Clearing, Grading and TESC Plan, Sheet 2 of 6 and 3 of 6, by David Evans and Associates, Inc., dated November 1999. Dear Ms. McConnell: As the geotechnical engineer of record for the Sequoia Ridge Development project, it is our opinion that it is acceptable to allow site work to occur during the wet season, after September 30, for both the development of the general plat and construction on individual lots. It is our opinion that adverse impacts, such as site stability issues, protection of homes on individual lots, and off -site environmental concerns will be mitigated during the wet season through a combination of temporary erosion control measures, constructing the homes on deep piles, and the steep slope building setbacks. Geo Group Northwest, Inc. reserves the right to recommend halting site work and construction at any time if changes, in weather or site conditions should warrant. Sincerely, GEO GROUP NORTHWEST, INC. 4y WAS z William Chang, P.E. Principal "cj114 011 i cc: Mr. John Thoresen �arvA►.� �>� 2i t9J zooz !3240 NE 20th Street, Suite 12 • Bellevue, Washington 98005 Phone 425/649-8757 • FAX 425/649-8758 UMI Group November 2, 2000 Northwest, Inc. Mr. John Thoresen Sequoia Ridge Partners 15621 - 48'b Place West Edmonds, Washington 98026 Subject: Lot 2 Steep Slope Setback Review Sequoia Ridge Subdivision Edmonds, WA Dear Mr. Thoresen: Geotechnical Engineers, Geologists & Environmental Scientists G-1061 DECEIVED NOV . 6 2000 PERMIT COUNTER At your request, we have reviewed the steep slope building setback requirements for Lot 2 of the Sequoia Ridge Subdivision. The geotechnical engineering study recommends a steep slope building setback of 25 feet from the top of the steep west -facing slope on Lot 2, and a 15 foot setback on Lot 3 and Lot 4, provided the buildings are supported on deep pile foundation i systems. The Clearing, Grading and TESC Plan by David Evans and Associates, Inc. shows a 15 foot setback for Lots 2, 3 and 4. A 15 foot setback would be acceptable in the northern portion of Lot 2, as shown on the attached Lot 2 Steep Slope Setback Plan. The northern portion of Lot 2 has similar slope characteristics as those found on Lots 3 and 4. The 25 foot setback should be required at the southeast corner of Lot 2. Based on the preliminary site development plans for Lot 2, we understand the building will be located 25 feet from the top of the slope. A 15 foot setback would allow the placement of rockery walls so a yard can be leveled on the west side of the house. In our opinion, landscaping would.be acceptable up to the 15 foot top of slope setback. 13240 NE 20th Street, Suite 12 • Bellevue, Washington 98005 Phone 425/649-8757 • FAX 425/649-8758 • 10 November 2, 2000 Lot 2 Steep Slope Setback Review Sequoia Ridge Subdivision, Edmonds, WA If you have any questions, please contact us. Sincerely, GEO GROUP NORTHWEST, INC. GC G%L �ti J %VAS z � ��o - • ' coo Q William Chang, P. E. Principal' � 23114 Attachment: Lot 2 Steep Slope Setback Plan � �lOiSfAL� �a> 2119J2ooz- Geo Group Northwest, Inc. G-1061-2 Page 2 I /4,221 DLIMIT OFiCLEARING & jk[SING (TYPE SF ` J � <- •'I J 153.897 N01 *17'36"E o • . �� I 10 L cc 15 � ac N01-17'36'PE (�) ST 58.71' r! ;n it •'� w.o o I- _ > �17.5. �300— 007 \ 0-01 LIMIT OF CLEARING fi r?� & GRADING (TV) i � l 123.42' f�EOA RECEIVED NOV 0 610A, VELOPMENT SERVICH CTq, ITY OF EDMON9f )ter Zeman Associates Geotechnical and Environmental Consulting J-720 September 28, 2000 City of Edmonds Community Services Department RECEIVED 250 — 51h Avenue North Edmonds, Washington 98020 SEP 2 9oo� Attention: Ms. Jeannine Graf, Building Official BUILDING plrfft Subject: Geotechnical Review of September 20, 2000 Addendum Letter Proposed Thoresen Residence, Lot 2 of Sequoia Ridge 16521 48th Place West Edmonds, Washington Dear Ms. Graf: This letter supplements our geotechnical review of building permit application documents for the referenced project dated May 5, 2000. This supplement contains our review of supplemental information contained in the Geo Group Northwest, Inc. letter dated September 20, 2000. The plan review number for this project is 00-115. Zipper Zeman Associates, Inc. services were limited to geotechnical review for the referenced project. These review services do not include design, analysis, or engineering recommendations for the project. These review services were provided for the purpose of evaluating general conformance of the documents with City of Edmonds permit requirements. These services were provided for the exclusive use of the City of Edmonds for specific application to the referenced project and purpose. No other warranty is expressed or implied. A summary of the submittal status, as pertaining to geotechnical information, is enclosed with this letter. This summary is updated from our July 7 letter. After we receive additional information, particularly the grading plan to sufficient detail, additional review items may develop. Our July 7, 2000 letter recommended that the submittal be supplemented. Information submitted in response included the Geo Group Northwest, Inc. letter dated September 20, 2000. The following comments are based on the information in those letters, the rockery plan by Bientz Architectural dated July 12, and the rockery submittal by Geo Group Northwest, Inc. dated July 18. The supplemental information attempts to address all of the geotechnical items listed in our previous review comments. Our interpretations and understanding of the supplemental information are listed below. If we have misinterpreted the Geo Group responses, they should let us know. It is our understanding that Geo Group Northwest has analyzed all rockeries planned for the site, and has recommended design and construction criteria to provide f6r a factor of safety of 19231— 36'" Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771— 3304 J720,092700 City of Edmonds 40 0 J-720 Thoresen Residence, Lot 2 of Sequoia Ridge September 28, 2000 Page 2 2 or greater. This will require geogrid reinforcement of certain rockeries, and will require limiting the maximum height of certain rockeries. We have no reason to doubt the conclusions of the design engineer regarding these designs; our only remaining concern regarding the rockeries is confirmation of the design requirements consistent with the planned grading on the site. As an example of the need for such a plan, we have seen conflicting information regarding the design for the rockery between Lots 1 and 2, immediately upslope of the garage entrance to the proposed residence. We note that the rockery has been shown as 15 to 20 feet high, then was planned to not exceed 8 to 10 feet, and on the latest plan (dated July 12) is about 14 feet high. Also, the only submittal we have seen with the specific geogrid details for rockeries retaining fill is GeoGroup's June 6, 2000 response to Landau review comments. We understand that Landau already reviewed some of the rockeries, but are concerned that the height and construction details for the various rockeries are not specified on the plans. In addition to the requirement that the project grading plan reflect the height and construction details of all rockeries, we recommend that the locations and heights of geogrid-reinforced rockeries be shown on the plans. Concerning the rockery planned at the 15-foot setback line west of the house, it is our understanding that the excavation cannot extend closer than 15 feet from the top of slope. It sounds like this will be the case, based on the Geo Group Northwest, Inc. letter dated September 20, 2000. We recommend that the plans be updated to reflect this requirement. Our other comments in previous review letters have described the need for evaluation of the stability of the west -facing slope adjacent to the subject residence. The engineer has provided additional calculations regarding stability of the slope. The factors of safety calculated by the engineer support the engineer's conclusions. The engineer provided a copy of a topographic survey dated 1989 by Dowl Engineers for the downslope property (Lorian Woods). The survey confirms that the slope conditions are generally consistent with those referenced in previous reports. We take no exception to the engineer's conclusions regarding stability of the slope.. We appreciate the opportunity to have provided this review. Please feel free to call if you have any questions or need additional information. Respectfully submitted, Zipper Zeman Associates, Inc. __ (� . 3; 0- John E. Zipper, P. E. President Enclosure: Summary of Submittal Status: September 28, 2000 Zipper Zeman Associates, Inc. 19231 — 36t° Avenue W., Suite B201 Lynnwood, Washington 98036 22611 G4' 1ST ugh" 'EXPIRES J 124 ro (425) 771— 3304 J720,092700 City of Edmonds 0 Thoresen Residence, Lot 2 of Sequoia Ridge Enclosure Proposed Thoresen Residence, Lot 2 of Sequoia Ridge 16521 48th Place West Edmonds, Washington J-720 September 28, 2000 Page E-1 Summary of Submittal Status Ordinance No. 2661 of the City of Edmonds, dated January 27, 1988 and revised February 29, 1988 contains requirements for design, geotechnical analysis, construction, and permit submittal within the Meadowdale Slide area of Edmonds. Paragraph 19.05.000 of the ordinance defines the purpose of the ordinance. Paragraph 19.05.030 describes required application submissions. The following sections of this summary contain our conclusions regarding the submittals received by our office for this project, including conformance with the required application submissions noted in the ordinance. Additionally, this summary comments on conformance with Paragraph 19.05.050 of the ordinance, which describes disclosures, declarations, covenants, and waivers required for construction in the Meadowdale Slide area. The site evaluation checklist utilized for this review is titled "Meadowdale Earth Subsidence Landslide Hazard Area Checklist for Permit. Submittal' and appears to be dated May 1999. The status of the submitted geotechnical report by Geo Group Northwest, Inc. dated February 29, 2000 and additional submittals of June and September 2000 is summarized below: The following submittals are required by the referenced ordinance: Critical areas determination — Not submitted for our review. 2. Lead design professional designation and statement — Complete; 3. Vicinity Map — Complete. 4. Topographic Map — Reviewed; Does not show topography of west -facing slope on subject property. Does not show locations of "known landslide masses or debris flows on or near the site which could threaten proposed structures within 100 feet." Page 6 of the geotechnical report notes that evidence of recent sliding was present on the steep slope in the west part of lots 2 and 3. 5. Environmental Checklist — Complete; also reviewed EIS. 6. Land Clearing/Tree Cutting Plan — Plan sheet "Site" by Bientz Architectural dated 11/16/99, revised 2/28/2000 shows tree locations. A Land/Clearing Tree Cutting plan of the specified detail was not submitted for our review. Given the nature of the site, we recommend that a detailed clearing/TESC plan be submitted and reviewed. 7. Geotechnical Report — The geotechnical report is required to discuss all items within the referenced checklist and to make specific recommendations, as listed in the "Geotechnical Report Guidelines" dated May 1999 by the City of Edmonds. Our comments regarding the geotechnical report are contained in our letters. 8. Drainage Plan — Not submitted for our review. 9. Grading Plan — Plan sheet "Site" by Bientz Architectural dated 11/16/99, revised 2/28/2000 shows final site grades, but not to specified detail. As noted in our September 28, 2000 letter, we Zipper Zeman Associates, Inc. 19231 — 36`" Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771 — 3304 J720,092700 City of Edmonds J-720 Thoresen Residence, Lot 2 of Sequoia Ridge September 28, 2000 Enclosure Page E-2 recommend that the proposed rockery heights, locations, and construction details be clarified on a plan. 10. Architectural and Structural Plans — Reviewed; Pile depth not specified adequately on sheet S-4, detail 2. 11. Affidavit of Notice'of Application — Not submitted for our review. 12. Applicant/Owner Liability and Landslide Acknowledgement — Not submitted for our review. 13. Geotechnical Declaration and Statement of Risk — Reviewed; Considering all of the plan revisions to rockeries that have apparently occurred, engineer should specify which civil, structural, and architectural plans were reviewed. 14. Architect and/or Structural Engineer Declaration — Complete. 15. Applicant/Owner Covenant to Notify and Hold Harmless — Not submitted for our review. Zipper Zeman Associates. Inc. 19231 — 36'" Avenue W., Suite B201 Lynnwood, Washington 98036 1720,092700 (425) 771 — 3304 Geotechnical Engineers, Geologists 1 Group Northwest, Inc. & Environmental Scientists September 20, 2000 G-1061-1 _ F c,e S��t Ms. Jeannine Graf Development Services Department SEP 2 ' 21:O"O City of Edmonds v'l_c," la,: �l r- _ ,� r.r� `'l 121 5`' Avenue North Edmonds, WA 98020 Subject: Response to Geotechnical Review of Addendum Letter, June 6, 2000 Proposed Thoresen Residence, Lot 2 of Sequoia Ridge 16521 48' Place West Edmonds, Washington Plan Review Number: 00-115 Dear Ms. Graf. The purpose of this letter is to respond to the Geotechnical Review of our Addendum Letter dated June 6, 2000 by Zipper Zeman Associates, Inc. for the subject development of the Thoreson Residence. The geotechnical review comments were summarized in a letter by Zipper Zeman Associates, Inc dated July 7, 2000. Mr. William Chang of Geo Group Northwest, Inc. met with Mr. John Zipper of Zipper -Zeman Associates, Inc., Ms. Jeannine Graf of the City of Edmonds, and Mr. John Thoresen, the project. owner, on August 22nd in order to discuss issues raised by the Zipper -Zeman geotechnical review letter of July 7, 2000. It is our understanding that several of the reviewer's questions were discussed and resolved during the aforementioned meeting. The July 7, 2000 Zipper -Zeman letter indicates that we are in agreement with regards to the perched groundwater encountered in Boring B-2. (comment #1). In addition, we have discussed the use of rockeries on the cut and fill slopes at the project site with Mr. John Zipper of Zipper -Zeman of Zipper -Zeman Associates, Inc. As previously noted in our response to the Landau Associates Rockery Review, we have analyzed the stability of the Geo Group Northwest, Inc. �� GiL l/✓� 13240 NE 20th Street, Suite 12 • Bellevue, Washington 98005 Phone 425/649-8757 • FAX 425/649-8758 91 September 20, 2000 G-1061-1 Addendum Letter - Thoresen Residence Page 2 proposed rockeries and cut slopes at the project site, and determined that the rockeries shall have factors of safety equal to or greater than 2. In order to analyze the planned rockeries we have reviewed the Sequoia Ridge site develoment plans by David Evans and Associates, November 1999, the Lot 2 Thoresen Residence plans by the Bienz Architectural Group, dated November 16, 1999 and the "I 2-Foot Rockery with Fill X-Section" diagram prepared by Geo Group Northwest, Inc. (comment #2 & #5). Because the rockeries will be constructed in locations not subject to significant instability and some of the rockeries have been engineered to retain fill, it is our opinion, that the proposed rockeries meet the requirements of "feasible and attendant measures" to reduce the risk of earth movement. With regards to the possible excavation and disturbance within the 15-foot setback from the top of the slope (comment #3), we have provided a list of erosion control measures to be taken in our Addendum Letter (June 6, 2000). In general, disturbance to the vegetation within the 15 foot setback area should be avoided and the area should be re -vegetated as soon as possible after the rockery construction is complete in order to limit the erosion potential. We have listed the remainder of the reviewer's comments below and prepared the following responses. 4.) Comment: Our comment regarding the west -facing slope has not been addressed. The engineer should evaluate all required information for stability evaluation of this slope. Such information includes soil types and properties, groundwater conditions, topography, previous slide activity, and vegetation. The presence of seepage, areas of recent sloughing, and small slumps were reported on the steep west -facing slope. 4.) Response: A qualitative evaluation of the stability of the west -facing slope has been made and effectively Geo Group Northwest, Inc. September 20, 2000 G-1061-1 Addendum Letter - Thoresen Residence Page 3 described in the geotechnical study. Our general conclusions and recommendations regarding the stability of the slope have not changed since the geotechnical report was published February 29, 2000. However, we have performed further slope stability calculations using the XSTABL computer program and produced the following factors of safety with regards to the west -facing slope near lot 2. In addition, we have estimated the risk of failure within a 25 year period for each case of slope failure. Type of Slone Failure Factor of Safety Risk of Failure (25 yr) Shallow sloughing 1.1 10% Deep failure (affecting house) 1.8 1 % We have formulated the risk of failure percentage based upon similar estimates for the surrounding area made by RLA and Geoengineers, our calculated factors of safety, the existing condition of the slope, and the evidence that recent sloughing has occurred on the steep west - facing slope. D Comment: We don't understand how the engineer can comment on stability of the west -facing slope without evaluating topography or geologic conditions on the entire vertical height of the slope. 6.� Response: The topographic and geologic conditions of the entire vertical height of the slope have been described qualitatively in our geotechnical study. Based upon the Exploration Location Plan for the Lorian Woods project (attached) by Terra Associates, Inc. (3/89), the west -facing slopes below lot 2 have slope inclinations in the upper part of the slope ranging between 65 and 80 percent from the horizontal and the lower part of the slope between 30 and 60 percent from the horizontal. Although a specific exploration program Geo Group Northwest, Inc. September 20, 2000 G-1061-1 Addendum Letter - Thoresen Residence Page 4 was not developed on the west -facing steep slopes, we can extrapolate based upon our subsurface . exploration at the top of the slope and explorations by others near the base of the slope, that in general the exposed soils on the slope may consist of up to 20 feet of loose to dense silty SAND with gravel (glacial till) at the top of the slope. The glacially consolidated cap is underlain by a dense to very dense outwash SAND. Underlying the outwash sands, at a point approximately 60 feet below the top of the slope are the very stiff to hard SILTS and CLAYS of the Whidbey formation. Although it is unlikely that the Whidbey formation is exposed at any point along the slope, as forest duff and colluvium are likely the principal surface soils, it is our opinion that the contact between the outwash sands and the Whidbey formation probably exists near the location of the seepage on the steep slope (please see Plate 6 - Subsurface Profile B-B' of our report, 2/29/00). We are in general agreement with the Terra Associates report for Lorian Woods regarding the slope stability of the west -facing slope. Based upon the general topography of the slope and the soil conditions, we are of the opinion that a large proportion of the landslide risk to homes at the base of the slope is due to the possibility of periodic sloughing of the slope. The over -steepened portion of the slope is likely to continue to experience shallow sliding as result of natural weathering and plant growth. In general, it is our opinion, that the risk of deep-seated failure on the west -facing slope is relatively low, based upon our slope stability calculations and the most recent risk assessments performed by Geoengineers which indicate that large global failures have not occurred on the property. The mechanism which could produce a deep-seated slide surface is the washing out of soil at the contact between the outwash sands and the underlying Whidbey formation. We understand that the since the 1980's the groundwater in the Meadowdale area has been reduced through the installation of sanitary sewers, stormwater sewers, and subsurface interceptor drains on and around the project site. Because the proposed project includes the installation of additional sanitary sewers and stormwater sewers, it is our opinion that the risk of global failure at the site may be reduced even further than present calculations indicate following the completion of the project. Geo Group Northwest, Inc. September 20, 2000 G-1061-1 Addendum Letter - Thoresen Residence Page 5 D Comment: The engineer originally recommended, in the EIS documents and the geotechnical report, that specific geotechnical recommendations for pile lengths be further studied after the topography of the steep west -facing slope is better defined. There has been no better definition that we are aware of. Conformance with UBC 1806.5.3 can not be evaluated with the information presented. The engineer has misinterpreted the provisions of UBC 1806.5.3; the UBC setback of H/3 or 40 feet maximum is measured from a 1 H:1 V plane extended up from the toe of the slope, for slopes steeper than 1 H:1 V. In order to vary from the standard UBC setback, we recommend that the applicant be required to demonstrate and adequate factor of safety for the foundations. Response: We have reviewed the subsurface profile B-B' from our geotechnical report and the structural plans for the Thoresen Residence, Lot 2. Based upon the generalized slope profile and the anticipated top of the auger -cast pile foundation at approximately 285 feet, the proposed foundation has been set -back from the slope such that the bottom 19 feet of the auger -cast piles are outside of the 14/3' setback as measured from the 1H:1 V imaginary line from the base of the slope. Currently, the minimum length of the auger -cast piles is anticipated to be 25 feet as recommended in our geotechnical report for the project dated February 29, 2000. It is our opinion that the proposed auger -cast pile foundation meets the purpose and intent of UBC section 1806.5.3 and that it shall provide adequate adequate lateral confinement for the proposed building. Geo Group Northwest, Inc. a 1 0 September 20, 2000 Addendum Letter - Thoresen Residence Geotechnical Declaration and Statement of Risk It is the opinion of Geo Group Northwest, Inc.: G-1061-1 Page 6 a.) That the plans and specifications for the Thoresen Residence, Lot 2 of Sequoia Ridge prepared by the structural engineer conform to the recommendations in the geotechnical report; b.) That the risk of damage to the proposed Thoresen Residence, Lot 2 of Sequoia Ridge, or to adjacent properties, from soil instability will be minimal, subject to the conditions set forth in the geotechnical report, and that the proposed development will not increase the potential for soil movement; c.) That the statistical probability of earth movement within a 25 year period is as follows: Type of Slope Failure Factor of Safety Risk of Failure (25 yr) Shallow sloughing 1.1 10% Deep failure (affecting house) 1.8 1% The susceptibility of the risk or hazard to correction by on=site improvements is as follows: Type of Slope Failure Susceptibility Measures taken to Mitigate Risk Shallow sloughing Low 1.) Minimize disturbance to slope 2.) Install Erosion Control Measures Deep failure (affecting house) Low Indirectly reduce groundwater recharge through the installation of subsurface drainage structures. Geo Group Northwest, Inc. September 20, 2000 Addendum Letter - Thoresen Residence If you have any questions regarding this letter, please feel free to call us. Respectfully Submitted Geo Group Northwest, Inc. Adam Gaston Engineering Technician William Chang, P.E Principal r p,14 C m y11,�9 o rJ � x 20114 TONAL a 2/19J2pCJL. attachment: Figure 2: Exploration Location Plan Anderson Property From Terra Associates report, G-840-1, June 6, 1989 cc: Mr. John Zipper - Zipper Zeman Associates, Inc. Mr. John Thoreson - Sequoia Ridge Partners Geo Group Northwest, Inc. G-1061-1 Page 7 September 20, 2000 Addendum Letter - Thoresen Residence References G-1061-1 Page 8 GeoEngineers, 1985, Report of Geotechnical Consultation, Properly Value Appraisals and Assessments Meadowdale Landslide Area, Edmonds, Washington, GeoEngineers, Inc., for City of Edmonds, February 28, 1985. Geo Group Northwest, 2000, Geotechnical Engineering Study, Sequoia Ridge Short Subdivision, Edmonds, Washington, Geo Group Northwest, Inc., February 29, 2000. RLA, 1979, Final ReportLandslide Hazards Investigation, Meadowdale Area, Edmonds, Washingion, Roger Lowe Associates, Inc., for the City of Edmonds, October 16, 1979. Terra, 1989, Geotechnical ReportMeadowdale Beach Lots 54 to 57, Edmonds, Washington, Terra Associates, Inc., June 6, 1989. Geo Group Northwest, Inc. Is N. MEADOWDALF- RD. 'I. fits' 4.i' 45",..W a07 SO N F 0-tt ik. 4L A, A It v j6 0 N 11111 1 1114,11 '1 1 1 111111 Id, t '1111i I I"I & •{ e ' : ../ ////' I ,/ I 'lam,/.�l l'/'�/��! Z A �� ' III 1 1 I �� 94L Oil Al // lo P1, / Ill lo. I ith it I y1/ ��I� /.1+ /' / .!f t� � Illlullll,! '11,'Illl,,l lyl I1 ( \ .y ..�- .j Q � I IT � �� I ,Ill,n •1' II 11, '�, ,/,1 co r 01 1 11 lit I in / } •(' I �' 1 1 mj it t 011 \ \ � � � l I / I 'till I III I !�,�� \��\ ` I Ni ll l• a O / � // / I� II,II11111U' �'1'I II'' , j 0000 ' it 4'1 9D 35 43' F IZ6 no* I f 1� ;/ f� I I 'ti ��/ I l \L II -4 1 � ,; I' 1, , I � � •.: _ - -.:{, , ', � I (• r,, ; "� ' • �- ,C:' I /� 1 1 �� I 1, . ,`; . �a.. . � `, � (: 11.E "• �� 8 /l l � /('m ' III I _ _ \_ \ � ��Ir• •: jam-'•-!•t,: / /' r. 061 r 4/ ll � �� .� I��II I � � / I �'`, 0) It Ml W LA 0 9 CA71 AL L I M I T E D P A R T N E R S H I P MUTUAL BANCSHARES CAPITAL, INC., GENERAL PARTNER September 19, 2000 Mr. John J. Westfall Fire Marshall City of Edmonds 121 5'' Ave. N Edmonds, WA 98020 Dear Mr. Westfall: • Thank you for your letter of September 12 and our conversation regarding fire protection for lots 2 and 3 at Sequoia Ridge. I am addressing this letter only as it relates to my personal house on lot 2. I have spoken with Trinity Fire Protection Company who is a licensed and bonded installer of NFPA 13 D Sprinkler Systems. After my conversation with them I would like to propose the following for my house on lot 2. 1. Even though the system requires at least a % to 1 inch water line, we will be installing a 1 '/2 inch line to Lot 2 as well as the other lots in Sequoia Ridge. 2. Maximum full sprinkler coverage will be installed. 3. A remote waterflow monitoring system will be installed. 4. A covenant will be established for continued maintenance, monitoring, and period testing of the system. I will submit a design and a permit for your review within the next 30 days. We are anticipating installing the system beginning about November or December. I am told that the installers will do an early test of the system prior to sheetrock being installed. I am looking forward to working with you on this matter. The systems being installed today are very reliable, better engineered, and are being recognized by the insurance industry as a property and life saver. cc. Jeannine Graf 22020 17TH AVENUE SE. SUITE 220 BOTHELL. WA 98021-8486 TELEPHONE: 425-424.0058 FACSIMILE: 425.424.0809 E MAIL: BANCSHARES..LP@MSN.COM 0 CITY OF EDMONDS 121 - 5TH AVENUE NORTH • EDMONDS. WA 98020 • (425) 771-0215 • FAX (425) 775-7721 FIRE DEPARTMENT ncC. 189v GUI'LbING S E P 12 2000 Mr. John Thoreson 22020 171h Ave SE Ste. 220 Bothell, WA 98021 Dear Mr. Thoreson: GARY HAAKENSON MAYOR September 12, 2000 Evaluation of the construction requirement for the existing hydrant to serve your subdivision at 161 xx 72Id Avenue W. indicates there are parcels falling outside of the required hydrant spacing. The following excerpt is from the Edmonds Community Development Code 19.75.140C: In areas zoned for single-family residential use, public hydrants shall be spaced no more than 600 feet apart.. If dead-end streets, or driveways, singly or in combination, are over 300 feet long additional public hydrants shall be installed so that the public hydrant spacing is not over 600 feet. _ The distance to the nearest hydrant for lots 2 and 3 exceed 300' for the purpose of fire flow for the structure along the private drive. Fire access standards and fire protection water standards work in concert with each other. The availability of water within the standard distance may not meet the intent if also standards for Fire access are not provided, allowing the Fire Department to promptly bring that water in to an emergency when it occurs. Water supply requirements for fire protection may be modified by the Fire Chief where practical difficulties exist, provided that the spirit of fire protection and safety is met and substantial justice is. accomplished (Uniform Fire Code 103.1.3). I am willing to review your proposal for an alternative to municipal fire protection water supply. The installation of a residential fire sprinkler system built in accordance with National Fire Protection Association (NFPA) Standard 13D, Sprinkler Systems in One - and Two- Family Dwellings, has been accepted for other properties where fire access or fire protection water supply fall short of City standards. • Incorporated August 11, 1890 • r•.. �•. r r r r I 1 ask that your proposal include the following minimum prescriptive requirements: 1. • Installation of a fire protection system in accordance with NFPA 13 D, Sprinkler Systems in One- and Two- Family Dwellings, 2. Maximum full sprinkler coverage in attached heated garage area, or minimum additional opening protection in area adjacent to the living space of attached unheated garage, and 3. Covenant established to meet continued maintenance, monitoring and periodic testing requirements in accordance with the standard. 4. Remote waterflow monitoring for the system. 5. A separate permit and review will be required for the system installation. State - certified sprinkler designers/installers must be used for the scope of sprinkler work. My office phone is (425) 771-0213 if you have questions. I await your written proposal if you choose to seek an alternate to City fire protection water standards. SWhal) JF cc: Jeannine Graf, Building Official Don Fiene, Acting City Engineer H • • � STREFILE COPY Q ET RECEIVED JUL. 14 20M July 14, 2000 PERMIT COUNTER TO: City of Edmonds Building Department FROM: John E. Thoresen RE: Permit # 00-11�'� I would request a variance for the driveway construction of my home for a portion of the driveway. To ease the "hinge" effect entering the garage, the architect has proposed a portion of the driveway be built at lg% grade with the remainder at 7%. I have enclosed a driveway section to illustrate. Thank you. v 5ARA6E 1� SLOPE 18% SLOP_ 264.00, =- - - - --- — — -- — — - - — -- --- - -- - -- --- -- --- - - - - - - ----- - - - ---- ----- -- -- - 2BO.00' C-L. • 1630140ih Avenue Na Reel We 200 BAUBVUe, W8ehimpfl 88006 (425)146-2"5 Fu (425) SK--29N Tj - Driveway Section c n D y The Thoresen Family P o < Lot 2 Sequoia Ridge Q M Scale:114"=1'-0" July 12, 2000 Grouo Northwest, July 19, 2000 Mr. Jobn .Thoreson Sequoia Ridge ParMm 1562148'h Place West Edmonds, Washington 99026 Subject: Rockery flan Review Tboreson Residence Lot 2, Sequoia Ridge Development Edmonds, Washington Dear M. Tboreson: n Qeoteehnlaal "Inee►s. 0"tugwls tic*6 Environmental solarium 0-1061-1 At your request we have reviewed the architectural site plans, for the construction of rockeries at the proposed Thoreson Residence, Lot 2 of the Sequoia Ridge Development, Edmonds, Washington. We have reviewed the "Rockery Plan" for the subject site created by The Bien Architectural Group, Inc., dated July 12, 2000. Based upon the plan, a maximum 9 foot high rockery will' be constructed near the northwest corner of the house and will rum west from the house and then south along the setback line, a 6 to 8 foot high rockery will be constructed along the setback line running south to the southwest corner of the house and.then running east along the length of the house's southern exterior�wall, and a maximum. 9 foot high rockery will be constructed in the front yard of the new residence, from the house to the (site development) ten foot rockery on the west side of the new roadway. We understand that the excavation for the western rockeries may extend no more than one or two feet into the 15 foot setback area from the top of the west -facing slope on Lot 2. It is our opinion, based upon the proposed location and heights of the mckieries, that the Rockery Plan has been prepared in general accordance with our geotechnical recommendations. We. recommend that the rockeries be constructed in accordance with our geotecbuiteal recommendations in the geotechnical engineering study and the Association of Rockery Contractor's Standard Rockery Construction Guidelines. We appreciate this opportunity to provide you with geotechnical consulting -services. If you have any questions, please call. r 13240 NE 20M Street, Suite 12 • Bellevue, Washington 98005 Phone 4251649.8767 • FAX 425/e4e-875a G-1061-1 July 18, 2000 page 2 Rockery Plan Review-'Thoreson Residence Sincerely, GEO GROUP NORTHWEST, INC. �Gm /d� Adam Gaston Engineering Technician William Chang, P.E. Principal Geo Group Northwest, Inc. A • 12 FOOT ROCKERY WITH FILL X-SECTION TENSAR UX1500 GEOGRID 6 FT CLEAN QUARRY SPALL DRAIN ROCK 1 FT THICKNESS .4 INCH DIAM. PERF. PVC PIPE ROCKERY CONSTRUCTION SPECIFICATIONS 1.) Rock shall be hard, durable 6-Men (7000 lb) rock for basal 3-courses, remainder shall be 4-Man rack. 2.) Long dimension of rock shall extend into earth and each rock should bear on two or more rocks 3.) Drainage material shall consist of clean quarry spans with 3 inch maximum size 4.) Drain pipe shall be 4 inch diameter perforated PVC pipe laid in drain, rock with gradient to discharge tightline 5.) Rockery shall be embedded at least 18 inches and shall bear on native dense soils 6.) Rockery face shall not exceed 1H:6V (Horizontal: Vertical) inclination 7.) Qeo-grids shall be 6 foot length Tensar UX1500 or equivalent, laid flat on prepared level surface, overlap 1 ft 8.) Fill shall be Sand, (travel or Pit -run fi= of deleterious or organic material, placed in 8 inch lifts & compacted 9.) All fill shall be compacted to meet or exceed 90°/a of modified proctor max dry density (A,STM-D-1557) ROCKERY CONSTRUCTION PROCEDURE 3 FT 3 FT ---7K 2 FT —�14 1.) Fill bench shall be excavated, and existing topsoil, loose soils and vegetation shall be removed from the -slope 2:) Fill shall be placed & compacted & geo-grids placed as shown in diagram - up to proposed road subgrade 3.) Placed and compacted fill wedge area shall be cut at proposed rockery location 4.) . Rockery shall be constructed against cut fill wedge at the same time drainage system is installed 07/07/2000 17:55 4257713549 ZIPPER ZEMAN ASSOCIA PAGE 02 a .2 Paper Zeman ocia Yn Gebtechnical and Environmental Consulting City of Edmonds Community Services Department 250 — 5th Avenue North Edmonds, Washington 98020 Attention: Ms. Jeannine Graf, Building Official Subject: Geotechnical Review, of June 6, 2000 Addendum Letter Proposed Thoresen Residence, Lot 2 of Sequoia Ridge 16521 481h Place West Edmonds, Washington Dear Ms. Graf: J-720 July 7, 2000 G 201 This letter supplements our geotechnical review of building permit application documents for the referenced project dated May 5, 2000. This supplement contains our review_ of supplemental information contained in the Geo Group Northwest, Inc. letter dated June 6, 2000. The plan review number for this project is 00-115. Zipper Zeman Associates, Inc. services were limited .to geotechnical review for the referenced project. These review services do not include design, analysis, or engineering recommendations for the project. These review services were provided for the purpose of evaluating general conformance of the documents with City of Edmonds permit requirements. These services were provided for the exclusive use of the City of Edmonds for specific application to the referenced project and purpose. No other warranty is expressed or implied. A summary of the submittal status, as pertaining to geotechnical information, is enclosed with this letter. This summary is essentially unchanged from our May 5 letter. After we receive additional information, particularly the grading plan to sufficient detail, additional. review items may develop. Our May 5, 2000 letter recommended that the submittal be supplemented to address the following general topics: 1. The conclusions of the report. should be re-evaluated in consideration 'of the probable seasonal presence of perched groundwater at higher elevation than assumed. 2. "Employing all feasible attendant measures" to reduce the risk of earth movement requires that an engineered retaining structure be used in lieu of rockeries. 3. Excavation for the rockery west of the house will extend into the 15 foot setback. 19231 - 36"^ Avenue W, sure B201 Lynnwood, Washington 98036 (425) 771 - 3304 1720,070700 07/07/2000 17:55 4257713549 PAGE 03 City of Edmonds 0 Thoresen Residence, Lot 2 of Sequoia Ridge ZIPPER ZEMAN ASSOCIA • J-720 July 7, 2000 Page 2 4.1 Because the stability of the west -facing slope in question affects the foundation support, we recommend that it be analyzed in sufficient detail to confirm that static and seismic factors of safety exceed building code requirements. 5. We recommend that a numerical factor of safety be calculated for all graded areas, including the east -facing slope and areas supporting foundations. 6. The engineer_ should independently determine the statistical 'probability of earth movement within a 25-year period, the susceptibility of the risk or hazard to correction by on -site improvement, and the measures taken to mitigate the risk or hazard. 7. The engineer recommends that specific foundation pile lengths be studied after topography of the west -facing slope is better defined. We recommend that geologic conditions at depth also be better defined, and the stability of the pile -supported house be analyzed in greater detail. The 25-foot setback recommended by the engineer should be compared to criteria referenced in UBC Section 1806.5.3. The June 6, 2000 supplemental letter by Geo Group Northwest contains supplemental information regarding all of the items listed above. Our interpretations and understanding of the supplemental information are listed below. if we have misinterpreted the Geo Group responses, they should let us know. 1. Geo Group concludes that the perched groundwater encountered in Boring B-2 is not significant considering the limited recharge area. We agree. 2. In our opinion, the use of engineered retaining structures should be required on the site for retaining all fills and:all cuts subject to potential instability. The use of rockeries for purposes other than erosion protection of an otherwise stable cut slope does not meet the requirement for "employing all feasible attendant measures" to reduce the .risk of earth movement. The Association of Rookery Contractors guidelines enclosed with the geotechnical report state that a rockery "is not a designed or engineered system." ` In order to provide detailed engineering conclusions regarding the rockeries, a detailed grading plan should be referenced by the engineer. 3. If excavation or disturbance of vegetation in the 15-foot setback from top of slope is not permitted, the grading plan for the back yard should be revised. 4. Our comment regarding the west -facing slope has not been addressed. The engineer should evaluate all required information. for stability evaluation of this slope. Such information includes soil types and properties, groundwater conditions, topography, previous slide activity, and vegetation. The presence of seepage, areas of recent sloughing, and small slumps were reported on the steep west -facing slope. Z(iper Zeman Assodates.Inc. 19231 — 36°i Avenue W., Suite B201 Lynnwood, Washington 98036 (425) 711— 3304 1720,070700 07/07/2000 17:55 4257713549 ZIPPER ZEMAN ASSOCIA PAGE 04 City of Edmonds • J-720 Thoresen Residence, Lot 2 of Sequoia Ridge July 7, 2000 Page 3 5. The engineer indicates that a factor of safety exceeding 2 has been calculated for all graded areas of the site. The detailed grading plan required for permit submittal should be provided to us for review. 6. We don't understand how the engineer can comment on stability of the west -facing slope without evaluating topography or geologic conditions on the entire vertical .height of the slope. 7. The engineer originally recommended, in the EIS documents and the geotechnical report, that specific geotechnical recommendations for pile lengths be further studied after the topography of the steep west -facing slope is better defined. There has been no .better definition that we are aware of. Conformance with UBC 1806.5.3 can not be evaluated with the information presented. The engineer has misinterpreted the provisions of UBC 1806.5.3; the UBC setback of H/3 or 40 feet maximum is measured from a 1H:1V plane extended up from the toe of slope, for slopes steeper than 1H:IV. In order to vary from the standard UBC setback, we recommend that the applicant be required to demonstrate an adequate factor of safety for the foundations. i We appreciate the opportunity to have provided this review. Please feel free to call if you have any questions or need additional information. Respectfully submitted, Zipper Zeman Associates, John E. Zipper, . E. President Enclosure: Summary of Submittal Status: July 7, 2000 11 19231 - 36' Avenue W., Suite B201 Zapper Zeman Associates; Inc. Lynnwood, Washington 93036 cP1R6s f / 24 i d (425) 771 — 3304 J720,070700 07/07/2000 17:55 4257713549 ZIPPER ZEMAN ASSOCIA PAGE 05 City of Edmonds J-720 Thoresen Residence, Lot 2 of Sequoia Ridge July 7, 2000 Enclosure Page E-1 Proposed Thoresea Residence, Lot 2 of Sequoia Midge Summary of Submittal Status 1652148' Place West Edmonds, Washington Ordinance No. 2661 of the City of Edmonds, dated January 27, 1988 and revised February 29, 1988 contains requirements for design, geotechnical analysis, construction, and permit submittal within the Meadowdale Slide area of Edmonds. Paragraph 19.05.000 of the ordinance defines the purpose of the ordinance. Paragraph 19.05.030 describes required application submissions. The following sections of this summary contain our conclusions regarding the submittals received by our office for this project, including conformance with the required application submissions noted in the ordinance. Additionally, this summary comments on conformance with Paragraph 19.05.050 of the ordinance, which describes disclosures, declarations, covenants, and waivers required for construction in the Meadowdale Slide area. The site evaluation checklist utilized for this review is titled "Meadowdale Earth Subsidence Landslide Hazard Area Checklist for Permit Submittal" and appears to be dated May 1999. The status of the submitted geotechnical report by Geo Group Northwest, Inc. dated February 29, 2000 is summarized below: The following submittals are required by the referenced ordinance: 1. Critical areas determination — Not submitted for our review. 2. Lead design professional -designation and statement — Reviewed; Does not include the required statement that engineer has "incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report." 3_ Vicinity Map — Complete. 4. Topographic Map — Reviewed; Does not show topography of west -facing slope on subject property. Does not show locations of "known landslide masses or debris flows on or near the site which could threaten proposed structures within, 100 feet." Page 6 of the geotechnical report notes that evidence of recent sliding was present on the steep slope in the west part of lots 2 and 3. 5. Environmental Checklist — Complete; also reviewed EIS. 6. Land Clearing/Tree Cutting Plan — Plan sheet "Site" by Bientz Architectural "dated 11/16/99, revised 2/28/2000 shows tree locations. A Land/Clearing "free Cutting plan of the specified detail was not submitted for our review. Given the nature of the site, we recommend that a detailed clearing/TESC plan be submitted and reviewed. 7. Geotechnical Report — The geotechnical report is required to- discuss all items within the referenced checklist and to make specific recommendations, as listed in the "Geotechnical Report Guidelines" dated May 1999 by the City of Edmonds. Our comments regarding the geotechnical report are contained in our letter dated May 5, 2000 and supplemental letter dated July 7, 2000. 8. Drainage Plan — Not submitted for our review. J Wiper Zeman Associates, Inc. 19231 — 36'h Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771 — 3304 1720,0?0700 i 07/07/2000 -17:55 4257713549 ZIPPER ZEMAN ASSOCIA PAGE 06 i, n • City o f Edmonds J-720 Thoresen Residence, Lot 2 of Sequoia Ridge July 7, 2000 Enclosure Page E-2 9. Grading Plan — Plan sheet "Site" by Bientz Architectural dated 11/16/99, revised 2/28/2000 shows final site grades, but not to specified detail. 10. Architectural and Structural Plans — Reviewed; Pile depth not specified adequately on sheet S-4, detail 2. 11. Affidavit of Notice of Application — Not submitted for our review. 12. Applicant/Owner Liability and Landslide Acknowledgement — Not submitted for our review. 13. Geotechnical Declaration and Statement of Risk — Reviewed; States that "design and construction plans for Lot 2 dated January 18, 2000" were reviewed. Final plans should be reviewed, and engineer should specify which civil, structural, and architectural plans were reviewed. 14. Architect and/or Structural Engineer Declaration — Reviewed; Does not include the required statement that engineer has "incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report." 15. Applicant/Owner Covenant to Notify and Hold Harmless — Not submitted for our review. Zipper Zemin Associates. Inc. 19231 — 36' Avenue W., Suite B201 Lynnwood, Washington 98036 (425) 771 — 3304 J720,070700 Zi f er Zeman Associates I Geotechnical and Environmental Consulting City of Edmonds Community Services Department 250 — 5`h Avenue North Edmonds, Washington 98020 Attention: Ms. Jeannine Graf, Building Official J-720 July 7, 2000 ��8EET FILE Subject: Geotechnical Review of June 6, 2000 Addendum Letter Proposed Thoresen Residence, Lot 2 of Sequoia Ridge®� 16521 48th Place West Edmonds, Washington Dear Ms. Graf: This letter supplements our geotechnical review of building permit application documents for the referenced project dated May 5, 2000. This supplement contains our review of supplemental information contained in the Geo Group Northwest, Inc. letter dated June 6, 2000. The plan review number for this project is 00-115. Zipper Zeman Associates, Inc. services were limited to geotechnical review for the referenced project. These review services .do not include design, analysis, or engineering recommendations for the project. These review services were provided for the purpose of evaluating general conformance of the documents with City of Edmonds permit requirements. These services were provided for the exclusive use,. of the City of Edmonds for specific application to the referenced project and purpose. No other warranty is expressed or implied. A summary of the submittal status, as pertaining to geotechnical information, is enclosed with this letter. This summary is essentially unchanged from our May 5 letter. After we receive additional information, particularly the grading plan to sufficient detail, additional review items may develop. Our May 5, 2000 letter recommended that.the submittal be supplemented to address the following general topics: �."1. The conclusions of the; report should be re-evaluated in consideration of the probable seasonal presence of perched groundwater at higher elevation than assumed. 2. "Employing all feasible attendant measures" to reduce the risk of earth movement requires that an engineered retaining structure be used in lieu of rockeries. 3. Excavation for the rockery west of the house will extend into the 15 foot setback. :i, 19231 — 36'" Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771— 3304 C J720,070700 . City of Edmonds • J-720 Thoresen Residence, Lot 2 of Sequoia Ridge July 7, 2000 Page 2 4. Because the stability of the west -facing slope in question affects the foundation support, we recommend that it be analyzed in sufficient detail to confirm that static and seismic factors of safety exceed building code requirements. 5. We recommend that a numerical factor of safety be calculated for all graded areas, including the east -facing slope and areas supporting foundations. 6. The engineer should independently determine the statistical probability of earth movement within a 25-year period, the susceptibility of the risk or hazard to correction by on -site improvement, and the measures taken to mitigate thexisk or hazard. 7. The engineer recommends that specific foundation pile lengths be studied after topography of the west -facing slope is better defined. We recommend that geologic conditions at depth also be better defined, and the stability of the pile -supported house be analyzed in greater detail. The 25-foot setback recommended by the engineer should be compared to criteria referenced in UBC Section 1806.5.3. The June 6; 2000 supplemental letter .by Geo Group Northwest contains supplemental information regarding all of the items listed above. Our interpretations and understanding of the supplemental information are listed below. If we have misinterpreted the Geo Group responses, they should let us know. 1. Geo Group concludes that the perched groundwater encountered in Boring B-2 is not significant considering the limited recharge area. We agree. 2. In our opinion, the use of engineered retaining structures should be required on the site for retaining all fills and all cuts subject to potential instability. The use of rockeries for purposes other than erosion protection of an otherwise stable cut slope does not meet the requirement for "employing all feasible attendant measures" .to reduce the risk of earth movement. The Association of Rockery Contractors guidelines enclosed with the geotechnical report state that a rockery "is not a designed or engineered system." In order to provide detailed engineering conclusions regarding the rockeries, a detailed grading plan should be referenced by the engineer. 3. If excavation or disturbance of vegetation in the 15-foot setback from top of slope is not permitted, the grading plan for the back yard should be revised. 4. Our comment regarding the west -facing slope has not been addressed. The engineer should evaluate all required information for stability evaluation of this slope. Such information includes soil types and properties, groundwater conditions, topography, previous slide activity, and vegetation. The presence of seepage, areas of recent sloughing, and small slumps were reported on the steep west -facing slope. Zipper Zeman Associates, Inc. 19231— 36ih Avenue W., Suite B201 Lynnwood, Washington 98036 (425) 771— 3304 J720,070700 City of Edmonds • J-720 Thoresen Residence, Lot 2 of Sequoia Ridge July 7, 2000 Page 3 5. The engineer indicates that a factor of safety exceeding 2 has been calculated for all graded areas of the site. The detailed grading plan required for permit submittal should be provided to us for review. 6. We don't understand how the engineer can comment on stability of the west -facing slope without evaluating topography or geologic conditions on the entire vertical height of the slope. 7. The engineer originally recommended, in the EIS documents and the geotechnical report, that specific geotechnical recommendations for pile lengths be further studied after the topography of the steep west -facing slope is better defined. There has been no better definition that we are aware of. Conformance with UBC 1806.5.3 can not be evaluated with the information presented. The engineer has misinterpreted the provisions of UBC 1806.5.3; the UBC setback of H/3 or 40 feet maximum is measured from a 1H:1V plane extended up from the toe of slope, for slopes steeper than 1H:IV. In order to vary from the standard UBC setback, we recommend that the applicant be required to demonstrate an adequate factor of safety for the foundations. We appreciate the opportunity to have provided this review. Please feel free to call if you have any questions or need additional information. Respectfully submitted, Zipper Zeman Associates, ' • Zj John E. Zipper, . E. m President .e , 2281t �"t' ��GISTEg�9 Enclosure: Summary of Submittal Status: July 7, 2000 jXPIRES _ t / 24! O 1 ;"?ft19231 — 36ih Avenue W., Suite B201 Zipper Zeman Associates. Inc. Lynnwood, Washington 98036 (425) 771— 3304 .. "-RW20,070700 City of Edmonds is Thoresen Residence, Lot 2 of Sequoia Ridge Enclosure Proposed Thoresen Residence, Lot 2 of Sequoia Ridge 16521 48`h Place West Edmonds, Washington J-720 July 7, 2000 Page E-1 Summary of Submittal Status Ordinance No. 2661 of the City of Edmonds, dated January 27, 1988 and revised February 29, 1988 contains requirements for design, geotechnical analysis, construction, and permit submittal within the Meadowdale Slide area of Edmonds. Paragraph 19.05.000 of the ordinance defines the purpose of the ordinance. Paragraph 19.05.030 describes required application submissions. The following sections of this summary contain our conclusions regarding the submittals received by our office' for this project, including conformance with the required application submissions noted in the ordinance. Additionally, this summary comments on conformance with Paragraph 19.05.050 of the ordinance, which describes disclosures, declarations, covenants, and waivers required for construction in the Meadowdale Slide area. The site evaluation checklist utilized for this review is titled "Meadowdale Earth Subsidence Landslide Hazard Area Checklist for Permit Submittal' and appears to be dated May 1999. The status of the submitted geotechnical report by Geo Group Northwest, Inc. dated February 29, 2000 is summarized below: The following submittals are required by the referenced ordinance: Critical areas determination — Not submitted for our review. 2. Lead design professional designation and statement — Reviewed; Does not include the required statement that engineer has "incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report." Vicinity Map — Complete. 4. Topographic Map — Reviewed; Does not show topography of west -facing slope on subject property. Does not show locations of "known landslide masses or debris flows on or near the site which could threaten proposed structures within 100 feet." Page 6 of the geotechnical report notes that evidence of recent sliding was present on the steep slope in the west part of lots 2 and 3. 5. Environmental Checklist — Complete; also reviewed EIS. 6. Land Clearing/Tree Cutting Plan — Plan sheet "Site" by Bientz Architectural dated 11/16/99, revised 2/28/2000 shows tree locations. A Land/Clearing Tree Cutting plan of the specified detail was not submitted for our review. Given the nature of the site, we recommend that a detailed clearing/TESC plan be submitted and reviewed. 7. Geotechnical Report — The geotechnical report is required to discuss all items within the referenced checklist and to make specific recommendations, as listed in the "Geotechnical Report Guidelines" dated May 1999 by the City of Edmonds. Our comments regarding the geotechnical report are contained in our letter dated May 5, 2000 and supplemental letter dated July 7, 2000. 8. Drainage Plan — Not submitted for our review. Zipper Zeman Associates. Inc. 19231 — 36i° Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771 — 3304 J720,070700 City of Edmonds J-720 Thoresen Residence, Lot 2 of Sequoia Ridge July 7, 2000 Enclosure Page E-2 9. Grading Plan — Plan sheet "Site" by Bientz Architectural dated 11/16/99, revised 2/28/2000 shows final site grades, but not to specified detail. 10. Architectural and Structural Plans — Reviewed; Pile depth not specified adequately on sheet S-4, detail 2. 11. Affidavit of Notice of Application — Not submitted for our review. 12. Applicant/Owner Liability and Landslide Acknowledgement — Not submitted for our review. 13. Geotechnical Declaration and Statement of Risk — Reviewed; States that "design and construction plans for Lot 2 dated January 18, 2000" were reviewed. Final plans should be reviewed, and engineer should specify which civil, structural, and architectural plans were reviewed. 14. Architect and/or Structural Engineer Declaration — Reviewed; Does not include the required statement that engineer has "incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report." 15. Applicant/Owner Covenant to Notify and Hold Harmless — Not submitted for our review. Zipper Zeman Associates. Inc. m 19231 — 36'" Avenue W., Suite B201 Lynnwood, Washington 98036 1J720,070700 (425) 771 — 3304 �"�7-loge J CITY OF E D M O 1 V D S GARY HAAKENSON 121 5TH.AVENUE NORTH • EDMONDs, WA 98020 • (425) 771-0220 • FAX (425) 771.0221 MAYOR DEVELOPMENT SERVICES DEPARTMENT 1 v. Planning •Building.• Engineering �c.189 June 28, 2000 Mr. Jack Molver, PE David Evans and Associates, Inc. 1620 West Marine View Drive, Suite 200 Everett, WA 98201 SUBJECT: Sequoia Ridge (Thoresen) -162xx 72"d Avenue West (,S-98-108� Dear Mr. Molver, Before Don Fiene, Acting City Engineer, will sign the subject short plat drawings, he wants information placed on the drawings that reflects concerns expressed in Landau and Associates letter dated June 14, 2000. Enclosed please find a copy of the page from that report indicating Don's concerns. If the information can be placed on the drawing using self-adhesive sheets, please have someone stop by to place them on the drawings. I will. then have Don. sign the. drawings. If you have any questions, please call meat 425-771-0220, Ext. 1324. Sincerely; ADDISON L. CHRISMAN IV Acting Development Services Engineer ALCkmc c: ~`DSC John Thoresen; 15621-48 h Place West; Edmonds, WA 98026 I Incorporated August 11, 1890 • Sister City - Hekinan, Japan . COMMENT AND. RESPONSE 2 Geo Group Northwest has provided a table of geogrid depths, lengths; and type for fill depths, ranging from 4 to 8 ft. See also comment 3 below. COMMENT AND RESPONSE 3 Our comment was related to the construction slope configuration and the potential for more than 8 ft.of fill to be present behind the 12-ft high rockery. Geo Group Northwest states that .the rockery is designed to retain no more than 8 ft of compacted fill; greater depths of fill would either require a design revision or use of another retaining wall type. This limitation should be clearly stated on the rockery design details. '. COMMENT AND RESPONSE 4 �. Geo Group Northwest has provided a revised recommended construction sequence .that appears to be more constructable than the previously recommended construction sequence, although construction of a rockery partly in cut and partly with backfill'on an existing slope is still tricky. ADDITIONAL COMMENTS AND RESPONSE Comments received from Geo .Group Northwest (and telephone comments from Mr. John. Thoreson, the owner of Lot 2) indicate, that the grading in the area of the rockery between a portion of Lots 1 and 2, shown on plan sheet 2 of the David Evans and Associates plans,. does not accurately reflect the grading and additional retaining wall. planned as a part of the house construction.. We understand that the rockery in this area is not planned, to exceed about 8 to 10 ft in height.[We recommend.that plan sheet 2 be revised.to reflect the actual configuration, or a note be added to the plans referring tothe house plans for the current rockery configuration in that area. SUMMARY Geo Group Northwest has adequately addressed our preliminary review comments and. provided needed clarification to their design recommendations. We recommend that Geo Group Northwest develop . a revised rockery cross-section and text that incorporates the additional recommendations and design criteria provided in their June 6 response .letter, and the comments in this review letter. This revised.. cross-section. and text should either be included in the .David Evans and Associates plans or specificallyreferenced on the plans. W14/00 S:IWPR0C1074M9Vocheryrev_lel•Eoc LANDAU ASSOCIATES. 2 7 ENGINEERING June 16, 2000. John Thorson 22020 170' Avenue SE Suite 220 Bothell, WA 98021 .� 2W85 �4 L©� EXPIRES 09 / 05 / 20 Subject: Thorson Residence, 1652148"' Place West, Edmonds, WA Lead design declaration statement. Job #99122 Dear Mr. Thorson, This letter is to inform you that our office has reviewed the geotechnical report from GeoGroup Northwest, Inc. and B-Twelve Associates, Inc, No. G-1061 dated July 16, 1999, and understands its recommendations. The review indicates that the lot is in an area subject to ground failure. It is impossible to guarantee future slope stability, regardless of how well it is investigated or engineered, and risks are always associated with construction in a known hazard area. Among these risks is the possibility of the loss or damage to your property and life, as well as the property and life of neighbors, public and private, due to soil failure. Because of the unpredictable nature and wet condition of soils, owners must assume the responsibility for risks of building and living in this known hazardous area. The reports, recommendation, opinions, designs, and specifications associated with this project are professional opinions only and are not to be construed as a warranty, expressedor implied, against loss or damage. DECLARATION STATEMENT To the best of our knowledge and understanding, the building plans submitted with the permit application substantially incorporate the above -mentioned reports' recommendations. We have incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report. Careful and conscientious application of the above referenced recommendations during and after construction will apparently not increase the potential risk of injury or damage from earth movement associated with this site. Thank you, RECEIVED JUN 16 2000 STREET FILE DEVELOPMENT IOF EDMONDS C7R. C 4M ENGINEERING June 16, 2000 ca John Thorson 26385 22020 17'h Avenue SE Suite 220 �S�ONALO Bothell, WA 98021 EXPIRES Oa / OS / ZO Subject: Thorson Residence, 165214e Place West, Edmonds, WA Structural design declaration statement. Job #99122 COPY Dear Mr. Thorson, This letter is to inform you that our office has reviewed the geotechnical report from GeoGroup Northwest, Inc., and B-Twelve Associates, Inc. No. G-1061 dated July 16, 1999, and understands its recommendations. The review indicates that the lot is in an area subject to ground failure. It is impossible to guarantee future slope stability, regardless of how well it is investigated or engineered, and risks are always associated with construction in a known hazard area. Among these risks is the possibility of the loss or damage to your property and life, as well as the property and life of neighbors, public and private, due to soil failure. Because of the unpredictable nature and wet condition of soils, owners must assume the responsibility for risks of building and living in this known hazardous area. The reports, recommendation, opinions, designs, and specifications associated with this project are professional opinions only and are not to be construed as a warranty, expressed or implied, against loss or damage. DECLARATION STATEMENT To the best of our knowledge and understanding, the building plans submitted with the permit application substantially incorporate the above -mentioned reports' recommendation. We have incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report. Careful and conscientious application of the above referenced recommendations during and after construction will apparently not increase the risk associated with this site. Thank you, #11-� 4ail—li Greg Millen, PE "TREET FILE RECEIVED J U N 16 2000 DEVELOPMENT SERVICES CTR. CITY OF EDMONDS • 0 COPY Geotechnical Engineers, Geologists 1 Group Northwest, Inc. & Environmental Scientists April 18, 2000 Ms. Jeannine Graf Building Official City of Edmonds 121 Fifth Avenue North Edmonds, Washington 98020 RECEIVE® JUN 16 2000 DEVELOPMENT SERVICES CTR. CITY OF EDMONDS Subject: Geotechnical Declaration and Statement of Risk Sequoia Ridge Short Subdivision Edmonds, Washington Dear Ms. Graf: G-1061-1 . Geo Group Northwest, Inc., has prepared this letter regarding our review of the design and construction plans for the proposed Sequoia Ridge short subdivision in Edmonds, Washington. The project site, which consists of 3.66 acres, is proposed for subdivision and development into four single-family residential lots. We reviewed the design and construction plans for Lot 2 dated January 18, 2000. Based on our review, Geo Group Northwest finds that the foundation plan and relevant specifications are in conformance with the recommendations presented in our geotechnical engineering study report dated February 29, 2000, for the project site. In the judgement of Geo Group Northwest, Inc., the above -referenced plans and specifications prepared by the civil engineer conform to the recommendations in our geotechnical engineering study report dated February 29, 2000. The risk of damage to the proposed development or to adjacent properties from soil instability will be minimal, subject to the conditions set forth in our geotechnical report, and the proposed development will not increase the potential for soil movement. For the project site, the estimated probability of earth movement within a 25-year period is five (5) percent, based on the geotechnical investigation reports prepared by Roger Lowe and 13240 NE 20th Street, Suite 12 • Bellevue, Washington 98005 ST�� Phone 425/649-8757 • FAX 425/649-8758 V 77A 66�74 �rx.) • • April 18, 2000 G-1061-1 Ms. Jeannine Graf - City of Edmonds Page 2 Associates, dated 1979, and by GeoEngineers, Inc., dated 1985. We concur with this estimated probability. On -site improvements and measures to mitigate the risk or hazard of soil movement at the site include the following: • establishing building setbacks of 15 to 25 feet from the top of the steep west -facing slope at the site; • providing the p'roposed residences with connections to the local sanitary sewer and storm drain utility systems, and tightlining all roof, foundation, and wall drains and driveway catch basins to the storm drain system; '• incorporating City General Development Standards and implementing an Erosion and Sedimentation Control Plan during construction, • supporting the proposed residences located near the steep slope on deep pile foundation systems to protect the homes from potential damage by future sloughing events on the steep slope, and • establishing covenants between the City and the residents regarding vegetation and landscaping practices on the lots, maintenance of sewer and storm drain systems, and regulating construction of improvements such as swimming pools and ponds. The above items and additional measures are discussed in our geotechnical engineering study report, which should be consulted for further information. It is the judgement of Geo Group Northwest that these measures will reduce the susceptibility of the risk of soil movement and will mitigate the risk to the proposed structures. Respectfully Submitted, GEO GROUP NORTHWEST, INC. William Chang, P.E. Principal cc: Mr. John Thoresen, Sequoia Ridge Partners NM Q& 4 xmsas 211942pJZ C � ENGINEERING 111 Main Street Suite 106 Edmonds, WA 98020 Phone: 425.778.8500 Fax: 425.778.5536 June 16, 2000 John Thorson 25386 �a 22020 17"' Avenue SE Suite 220 �'S'�'ONAL � Bothell, WA 98021 _EXPIRES 09 / 05 / 20 Subject: Thorson Residence, 1652148`" Place West, Edmonds, WA Structural design declaration statement. Job #99122 Dear Mr. Thorson, This letter is to inform you that our office has reviewed the geotechnical report from GeoGroup Northwest, Inc., and B-Twelve Associates, Inc. No. G-1061 dated July 16, 1999, and understands its recommendations. The review indicates that the lot is in an area subject to ground failure: It is impossible to guarantee future slope stability, regardless of how well it is investigated or engineered, and risks are always associated with construction in a known hazard area. Among these risks is the possibility of the loss or damage to your property and life, as well as the property and life of neighbors, public and private, due to soil failure. Because of the unpredictable nature and wet condition of soils, owners must assume the responsibility for risks of building and living in this known hazardous area. The reports, recommendation, opinions, designs, and specifications associated with this project are professional opinions only and are not to be construed as a warranty, expressed or implied, against loss or damage. DECLARATION STATEMENT To the best of our knowledge and understanding, the building plans submitted with the permit application substantially incorporate the above -mentioned reports' recommendation. We have incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report. Careful and conscientious application of the above referenced recommendations during and after construction will apparently not increase the risk associated with this site. Thank you, Greg Millen, PE RECEIVE® JUN 16 2000 DEVELOPMENT SERVICES CTR. CITY OF EDMONDS Group Northwest, Inc. June 6, 2000 Mr. Greg Guillen CE Engineering 111 Main Street, Suite 106 Edmonds, WA 98020 S T RL F I L E RECEIVED J U N 16 2000 DEVELOPMENT SERVICES CTR, CITY OF EDMONDS Subject: Addendum Letter / Response to Geotechnical Review Proposed Thoreson Residence, Lot 2 of Sequoia Ridge Edmonds, Washington Plan Review Number: 00-115 Dear Mr. Guillen: Geotechnical Engineers, Geologists & Environmental Scientists G-1061-1 copy The purpose of this letter is to'respond to the Geotechnical Review by Zipper Zeman Associates, Inc. for the subject development of the Thoreson Residence. The geotechnical review comments were summarized in a letter by Zipper Zeman Associates, Inc dated May 5, 2000. We have listed each of the reviewer's comments below and prepared the following responses. In several instances we have referenced reports by others. A list of the cited references is attached to this letter. 1. Comment: The engineer interprets the depth to groundwater as greater than 30 feet on Lot 2, although Boring B-2 encountered seepage in the upper 2 or 3 feet during May 1999. The conclusions of the report, including stability of the west -facing slope, driveway cut and east -facing slope, should be re-evaluated in consideration of the probable seasonal presence of perched groundwater at higher elevation than assumed. Geo Group Northwest, Inc. 13240'NE 20th Street, Suite 12 • Bellevue, Washington 98005 Phone 425/649-8757 9 FAX 425/649-8758 June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 2 1. Response: We refer to the presence of a small amount of seepage in our report as "A very thin zone of wet soil (about 1 foot thick) was noted in the surficial weathered soils on top of the very dense glacial till in the boring on Lot 2" (Geo Group Northwest, 2000, pg 6). The area in question has very limited recharge. potential due to the fact that it is located on a ridge. It is our experience that in general, small seepage zones or areas of particularly wet soil may develop at the contact point between weathered and un-weathered glacially derived soil types as a result of the changing silt content and density of the soil. It is our opinion that the minimal seepage zone at 2 or 3 feet below ground surface will not affect the overall stability of the west -facing slope, driveway cut, or east -facing slope. The erosion associated with excavating the driveway cut shall be further minimized by the construction of a rockery which will provide permanent erosion protection. 2. Comment: In general, we are of the opinion that the City of Edmonds requirement that "employing all feasible attendant measures" to reduce the risk of earth movement requires that an engineered retaining structure be used in lieu of rockeries. The engineer should re-evaluate the use of tiered rockeries, and rockeries in the height range proposed. 2. Response: It is our opinion that the proposed construction of rockeries at the site are not for earth retaining purposes, but is a "feasible attendant measure" to reduce the risk of erosion potential and surficial soil sloughing at the driveway cut locations on the east facing slope. In order to further reduce the risk of earth movement, the 12 foot high rockeries with some fill will be reinforced by installing geo-grid and compacting all fill to structural fill specifications. It is our opinion that the proposed rockery sections, including the tiered rockeries and driveway access road on the east - facing slope, have a factor of safety equal to 2. In general, the site soils at the rockery locations Geo Group Northwest, Inc. 0 . 0 June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 3 consist of loose to medium dense silty sands to a depth of 4 feet. Accordingly, it is our opinion that the site soils may be susceptible to surficial sloughing and erosion. The installation of rockeries will provide protection from erosion and mitigate some of the risk of surficial sloughing on the steep slopes. 3. Comment: The plans seem to indicate that a rockery will be constructed west of the house at the "15 foot undisturbed area line". We expect that excavation for the rockery will extend into the 15 foot setback. The engineer should provide criteria to avoid disturbance in this area. 3. Response: We understand that the excavation for the rockery to be constructed at the "15 foot undisturbed area line" may extend no more than one to two feet into the 15 foot setback from the top of the west -facing slope. We recommend that the following measures be taken to avoid disturbance in this area: • Vegetation removal within the 15 foot setback area should be minimized; • The location of all temporary stockpiles, excavating equipment (trackhoes and backhoes), and rockery rocks shall be to the east of the 15 foot setback line; • All exposed soils shall be covered with visqueen during rain events; • The rockery shall be constructed in accordance with Association of Rockery Contractor's construction guidelines. 4. Comment: Geologic mapping of the west -facing slope would be a reasonable means of providing a geologic cross-section for stability evaluations. The subsurface profile B-B' in the geotechnical report does not accurately reflect the planned setback and grading. Because the stability of the slope in Geo Group Northwest, Inc. June 6, 2000 G-10614 Addendum Letter - Thoreson Residence Page 4 question affects the foundation support, we recommend that it be analyzed in sufficient detail to confirm that static and seismic factors of safety exceed building code requirements. 4. Response: The subsurface profile B-B' in our report shows locations of the planned setbacks and grading based upon the preliminary site planning. Based upon our understanding of the project the only addition to the B-B' profile is a level grade for the western yard of lot 2 (except for the `undisturbed area') and rockery as described above in #3. We have not been provided with detailed topography of the west -facing slope. Consequently, we have performed our slope stability evaluations of the west -facing slope based in general on the "Generalized Geologic Cross -Section and Topography" provided by the Terra Associates report for the Lorian Woods property to the west of the project site (Terra, 1989). We have analyzed the slope stability of the west -facing slope with regards to the foundation support for each of the lots, and determined that the pile supported foundations on lots 1,2, and 3 and the spread footing foundations on lot 4 will bear on the dense site soils far enough away from the steep slopes that the probability of sloughing and subsequent undermining of the building foundations is very low. Because the buildings.on lots 1, 2, and 3 will be supported on piles embedded 25 feet into the dense site soils, it is our opinion that there is very little, if any increased risk, of surficial sloughing or erosion on the steep slopes as a result of the new buildings. In our geotechnical report for the site we have provided recommendations based upon our understanding of the static and seismic soil conditions at the site. It is our opinion that the static and seismic factors of safety with regard to foundation support exceed building code requirements. 5. Comment: Similar stability evaluations are recommended for the east -facing slope. We recommend that a numerical factor of safety be calculated for all graded areas, and areas supporting foundations. Geo Group Northwest, Inc. June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 5 5. Response: Our analysis indicates that all graded areas and proposed rockeries at the project site will have a factor of safety equal to 2. It is our opinion that factor of safety calculations for the foundation areas near the east -facing slope are not necessary as the buildings on lots 2, 3, and 4 will be supported on deep foundations. The residence at lot 1 will be supported on a spread footing foundation which will bear on the dense site soils. Consequently, it is our opinion that the factors of safety for all foundation areas exceed 2. 6. Comment: The engineer seems to base his conclusions regarding stability on the probabilities described in the GeoErigineers report and predecessor report. It is our interpretation of the City's requirements that the engineer should independently determine the statistical probability of earth movement within a 25-year period, the susceptibility of the risk or hazard to correction by on -site improvement, and the measures taken to mitigate the risk or hazard. We recommend that the City determine whether this requires the property owner to mitigate the risk posed by the west -facing slope to downslope property. 6. Response: We used established and accepted criteria of risk for the Meadowdale area. We agree with the existing study in that the proposed building areas have not moved in the past, and that the slight risk is due to possible erosion and surficial sloughing. Therefore an estimate that a very site specific determination of earth movement probability is not appropriate at this time. We have used our site exploration as a verification that the geologic conditions at the project site are similar to those found in the previous studies, by GeoEngineers and others. Our subsurface exploration of the project site verifies that the surficial soils at the site are susceptible to sloughing and small scale surficial movement and that deeper movements are much less likely as a result of Geo Group Northwest, Inc. June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 6 the dense condition of the glacially over -ridden soils. Accordingly, we agree with the probabilities of earth movement which others have determined. According to the geotechnical reports by RLA (RLA, 1979) and GeoEngineers (GeoEngineers, 1985), the steep slopes along the southwest part of the proposed project site have a 5 percent probability of failure within 25 years, and the slopes in the north and northeast part of the site have a 2 percent probability of failing within 25 years. The reports characterize the landslide risk in the west part of the site as involving slumps of material that has not previously failed. The landslide risk in the north and northeast parts of the site are characterized as debris slides in material that has not previously failed. . The report by RLA (RLA, 1979) and to a lesser extent the report by GeoEngineers (GeoEngineers, 1985) provide recommendations and opinions regarding the overall susceptibility of risk reduction by site improvements. Based upon our exploration at the project site we concur with their recommendations that the most economically feasible and practically efficient way of lowering the risk of slope failure is to continue maintenance of existing drainage facilities in the Meadowdale Landslide Area and promote the installation of stormwater and sanitary sewer drainage systems with new development. Properly maintained stormwater and sanitary sewer drainage systems installed within the landslide hazard area can provide the advantageous effect of limiting the groundwater recharge within the landslide area. It is our opinion that lowering of the groundwater table on the project site will provide an increase in the stability of the slopes and a decrease in the risk of slope failure, at the project site. We understand that the site development plans include the addition of stormwater and sanitary sewer drainage systems in the roadway access areas. In order to further mitigate slope stability risks at the project site, we recommend that the footing, basement wall, and roof downspout drain lines be tightlined to the stormwater collection system. Geo Group Northwest, Inc. June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 7 7. Comment: The engineer recommends that specific foundation pile lengths be studied after topography of the west -facing slope is better defined. We recommend that geologic conditions at depth also be better defined, and the stability of the pile -supported house be analyzed in greater detail. The 25- foot setback recommended by the engineer should be compared to criteria referenced in UBC Section 1806.5.3. 7. Response: We have evaluated the pile foundation lengths based upon the "Generalized Geologic Cross - Section and Topography" provided in the Terra Associates report (.Terra, 1989). It is our opinion, that the minimum pile foundation lengths of 25 feet into the dense native soils as recommended in our geotechnical report is sufficient to allow for adequate slope confinement of the building foundations. The UBC Section 1806.5.3 indicates that the setback for buildings at the top of a slope where the slope is steeper than 1H:1 V may be measured from an imaginary plane 45 degrees to the horizontal projected upward from the base of the slope. Using the generalized topography of the west facing slope provided by the Terra Associates report (Terra, 1989) we have verified that the 25 foot setback for lot 2, 15 foot setback for lot 3 and 4, and 50 foot setback for lot 1 are within the acceptable setback requirements specified by the UBC. If you have any questions regarding this letter, please feel free to call us. Geo Group Northwest, Inc. • • June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 8 Respectfully Submitted Geo Group Northwest, Inc. William Chang, P.E. AT. T �02 0 Principal ..� 2et14 Pt pL cc: Mr. John Thoreson - Sequoia Ridge Partners fTP z Geo Group Northwest, Inc. • June 6, 2000 G-1061-1 Addendum Letter - Thoreson Residence Page 9 References GeoEngineers, 1985, Report of Geotechnical Consultation, Property Value Appraisals and Assessments, Meadowdale Landslide Area, Edmonds, Washington, GeoEngineers, Inc., for City of Edmonds, February 28, 1985. Geo Group Northwest, 2000, Geotechnical Engineering_Study, Sequoia Ridge Short Subdivision, Edmonds, Washington, Geo Group Northwest, Inc., February 29, 2000. RLA, 1979, Final Report, Landslide Hazards Investigation, Meadowdale Area, Edmonds, Washin Loon, Roger Lowe Associates, Inc., for the City of Edmonds, October 16, 1979. Terra, 1989, Geotechnical Report, Meadowdale Beach, Lots 54 to 57, Edmonds, Washington, Terra Associates, Inc., June 6, 1989. Geo Group Northwest, Inc. Z er Zeman Associates . Geotechnical and Env' onmental Consulting TREET FILE J-720 May 5, 2000 City of Edmonds Community Services Department 250 — 5th Avenue North Edmonds, Washington 98020 Attention: Ms. Jeannine Graf, Building Official Subject: Geotechnical Review Proposed Thoresen Residence, Lot 2 of Sequoia Ridge 16521 48`h Place West Edmonds, Washington Dear Ms. Graf: This letter presents our conclusions and recommendations concerning our geotechnical review of building permit application documents for the referenced project. These services were requested with your letter of transmittal dated March 29, 2000. The plan review number for this project is 00-115. Zipper Zeman Associates, Inc. services were limited to geotechnical review for the referenced project. These review services do not include design, analysis, or engineering recommendations for the project. These review services were provided for the purpose of evaluating general conformance of the documents with City of Edmonds permit requirements. These services were provided for the exclusive use of the City of ' Edmonds for specific application to the referenced project and purpose. No other warranty is expressed or implied. Ordinance No. 2661 of the City of Edmonds, dated January 27, 1988 and revised February 29, 1988 contains requirements for design, geotechnical analysis, construction, and permit submittal within the Meadowdale Slide area of Edmonds. Paragraph 19.05.000 of the ordinance defines the purpose of the ordinance. . Paragraph 19.05.030 describes required application submissions. The following sections of this letter contain -our conclusions regarding the submissions for this project, including conformance with the required application submissions noted in the ordinance. Additionally, this letter comments on conformance with Paragraph 19.05.050 of the ordinance, which describes disclosures, declarations, covenants, and waivers required for construction in the Meadowdale Slide area. A summary of the submittal status, as pertaining to geotechnical information, is enclosed with this letter. After we receive additional information, particularly the grading plan to sufficient detail, additional review items may develop. Based on our initial review and our understanding of the building permit submittal requirements, we recommend that the geotechnical report be supplemented as noted below. 19231— 36'" Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771 —3304 J720,050500 City of Edmonds Thoresen Residence, Lot 2 of Sequoia Ridge ® J-720 May 5, 2000 Page 2 • The engineer interprets the depth to groundwater as greater than 30 feet on Lot 2, although Boring B-2 encountered seepage in the upper 2 or 3 feet during May 1999. The conclusions of the report, including stability of the west -facing slope, driveway cut and east -facing slope, should be re-evaluated in consideration of the probable seasonal presence of perched groundwater at higher elevation than assumed. • In general, we are of the opinion that the City of Edmonds requirement that "employing all feasible attendant measures" to reduce the risk of earth movement requires that an engineered retaining structure be . used in lieu of rockeries. The engineer should re-evaluate the use of tiered rockeries, and rockeries in the height range proposed. ►l • The plans seem to indicate that a rockery will be constructed west of the house at the "15 foot undisturbed area line". We expect that excavation for the rockery will extend into the 15 foot setback. The engineer should provide criteria to avoid disturbance in this .area. • Geologic mapping of the west -facing slope would be a reasonable means of providing a geologic cross-section for stability evaluations. The subsurface profile B-B' in the geotechnical report does not accurately reflect the planned setback and grading. Because the stability of the slope in question affects the foundation support, we recommend that it be analyzed in sufficient detail to confirm that static and seismic factors of safety exceed building code requirements. Similar stability evaluations are recommended for the east -facing slope. We recommend that a numerical factor of safety be. calculated for all graded areas, and areas supporting foundations. • The engineer seems to base his conclusions regarding stability on the probabilities described in the GeoEngineers 'report and predecessor report. It is our interpretation of the City's requirements that the engineer should independently determine the statistical probability of earth movement within a 25-year period, the susceptibility of the risk or hazard to correction by on -site improvement, and the measures taken to mitigate the risk or hazard. We recommend that the City determine whether this requires the property owner to mitigate the risk posed by the west -facing slope to downslope property. The engineer recommends that specific foundation pile lengths be studied after topography of the west -facing slope is better defined. We recommend that geologic conditions at depth also be better defined, and the stability of the pile- supported house be analyzed in greater detail. The 25-foot setback recommended by the engineer should be compared to criteria referenced in UBC Section 1806.5.3. 19231 — 30h Avenue W., Suite B201 Zipper Zeman Associates. Inc. Lynnwood, Washington 98036 (425) 771— 3304 «eu-J720,050500 City of Edmonds J-720 Thoresen Residence, Lot 2 of Se oia Ridge May 5, 2000 Page 3 We appreciate the opportunity to have provided this review. Please feel free to call if you have any questions or need additional information. Respectfully submitted, Zipper Zeman Associates,,, 21 t wAs�1 John E. Zipper, P. E. President Enclosure: Summary of Submittal Status: May 5, 2000 Zipper Zeman Associates. Inc. 19231 — 36t6 Avenue W., Suite B201 Lynnwood, Washington 98036 J720,050500 If IV. 22611 w ��G15TER4� �SSIa11Al, EXPIRES 1 / 24 / o i (425) 771 — 3304 City of Edmonds Thoresen Residence, Lot 2 of Sequoia Ridge Enclosure Proposed Thoresen Residence, Lot 2 of Sequoia Ridge 16521 48`e Place West Edmonds, Washington J-720 May 5, 2000 Page E-1 Summary of Submittal. Status Ordinance No. 2661 of the City of Edmonds, dated January 27, 1988 .and revised February 29, 1988 contains requirements for design, geotechnical analysis, construction, and permit submittal within the Meadowdale Slide area of Edmonds. Paragraph 19.05.000 of the ordinance defines the purpose of the ordinance. Paragraph 19.05.030 describes required application submissions. The following sections of this summary contain our conclusions regarding the submittals received by our office for this project, including conformance with the required application submissions noted in the ordinance. Additionally, this summary comments on conformance with Paragraph 19.05.050 of the ordinance, which describes disclosures, declarations, covenants, and waivers required for construction in the Meadowdale Slide area. The site evaluation checklist utilized for this review is titled "Meadowdale Earth Subsidence Landslide Hazard Area Checklist for Permit Submittal' and appears to be dated May 1999. ' The status of the submitted geotechnical report by Geo Group Northwest, Inc. dated February 29, 2000 is summarized below: The following submittals are required by the referenced ordinance: Critical areas determination — Not submitted for our review. 2. Lead design professional designation and statement — Reviewed; Does not include the required statement that engineer has. "incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report." 3. Vicinity Map — Complete. 4. Topographic Map — Reviewed; Does not show topography of west -facing slope on subject property. Does not show locations of "known landslide masses or debris flows on or near the site which could threaten proposed structures within 100 feet." Page 6 of the geotechnical report notes that evidence of recent sliding was present on the steep slope in the west part of lots 2 and 3. Environmental Checklist — Complete; also reviewed EIS. Land Clearing/Tree Cutting Plan — Plan sheet "Site" by Bientz Architectural dated 11/16/99, revised 2/28/2000 shows tree locations. A Land/Clearing Tree Cutting plan of the specified detail was not submitted for our review. Given the nature of the site, we recommend that a detailed clearing/TESC plan be submitted and reviewed. " 7. Geotechnical Report — The geotechnical report is required to discuss all items within the referenced checklist and to make specific recommendations, as listed in the "Geotechnical Report Guidelines" dated May 1999 by the City of Edmonds. Our comments regarding the geotechnical report are contained in our letter dated May 5, 2000. 8. Drainage Plan — Not submitted for our review. Zipper Zeman Associates. Inc. a^- 19231 — 36i6 Avenue W, Suite B201 Lynnwood, Washington 98036 (425) 771— 3304 r:� • J720,050500 City of Edmonds J-720 Thoresen Residence, Lot 2 of Sequoia Ridge May 5, 2000 Enclosure Page E-2 9. Grading Plan — Plan sheet "Site" by Bientz Architectural dated 11/16/99, revised 2/28/2000 shows final site grades, but not to specified detail. 10. Architectural and Structural Plans — Reviewed; Pile depth not specified adequately on sheet S-4, detail 2. 11. Affidavit of Notice of Application — Not submitted for our review. 12. Applicant/Owner Liability and Landslide Acknowledgement — Not submitted for our review. 13. Geotechnical Declaration and Statement of Risk — Reviewed; States that "design and construction plans for Lot 2 dated January 18, 2000" were reviewed. Final plans should be reviewed, and engineer should specify which civil, structural, and architectural plans were reviewed. 14. Architect and/or Structural Engineer Declaration — Reviewed; Does not include the required statement that engineer has "incorporated into the design the established measures to reduce the potential risk of injury or damage from any earth movement predicted in the report." 15. Applicant/Owner Covenant to Notify and. Hold Harmless — Not submitted for our review. Zipper Zeman Associates. Inc. 19231— 36'" Avenue W., Suite B201 Lynnwood, Washington 98036 J720,050500 (425) 771 — 3304 111c.18ojv CITY, OF E D M O N D S GARY HAAKENSON MAYOR 121 5TH AVENUE NORTH. EDMONDS, WA 98020 - (425) 771-0220 • FAX (425) 771-0221 DEVELOPMENT SERVICES DEPARTMENT Planning • Building • Engineering April 10, 2000 BUILDING J U N 2 6 2000 Mr. Jack Molver, PE David Evans and Associates, Inc. 1620 West Marine View Drive, Suite 200 Everett, WA 98201 CHRON CORM Mailed o jg /eo�Z Faxed SUBJECT: Revised Site Plan for Thoreson at 160xx-72"d Avenue West (S-98-108) J Dear Mr. Molver, The City Engineer reviewed your revised civil site design. He noted the following revisions/corrections must be made before he authorizes construction. • The approximately fifteen feet high proposed rock .wall must be structurally designed and approved by a structural engineer, as it is proposed to retain fill material. When crossing utility lines, special provisions must be made. It appears that you propose ductile iron pipe for that reason.. The Engineer must approve that consideration. • Provide details for construction of the turnaround at the end of 72"d Avenue West. No existing contours or planned profile are provided, so it is impossible to ,ascertain how it will be constructed. If retaining walls are to be provided, they too will require structural design. • On the plan view of sheet 4/6, show the invert elevation for CB A-3. When the revisions are complete, .please submit one copy of the revised plans for final review. A bond for $160,000 must be put in place. Forms are available at the Development Services Department. Engineering review and inspection fee of $3,219 must be paid prior to construction authorization. If you have any other questions, do not hesitate to contact me at (425) 775-7744. Sincerely, GORDON C. HYDE Development Services Engineer GCH/cmc c: John Thoreson; 15621-48t° Place West; Edmonds, WA 98026 R:\ENGRIG0RDW108b.dm Incorporated August 11, 1890 • Sister Citv - Hekinan. Japan March 31, 2000 Memorandum TO: City of Edmonds Community Development Department FROM: John E. Thoresen RE: Lot 2 Sequoia Ridge Subdivision 161XX 72"d Ave W. I have submitted building plans for the above referenced lot. The accuracy of all permit submittal information is warranted by me in a form. which relieves the City of Edmonds and its staff from any liabilityassociated with reliance on such permit application submittals. While an application may reference the reports of prior public consultants to the city, all conclusions shall be those of myself and my design professionals (ECDC 19.05.030), and that I understand and accept the risk of developing in an area with potential unstable soils and that I will advise in writing any prospective purchasers of the site, or any perspective lessees of structures on the site, of the slide potential of the area. Sig Jo/ Thoresen Date 731e Subscribed and sworn to before me this `r day of , 2000. •9FAxn r, r:: •• GAsgy�, �• �•�,.u.ni:,sue. exP;• .9L otary Public in and for the State of Was ' gton s,, P�6 o';e'=v Residing at 'j'OF .° STREET FILE GARY HAAKENSON MAYOR 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 • FAX (425) 771-0221 DEVELOPMENT SERVICES DEPARTMENT Planning - Building • Engineering CH RON COPY Mailed o 3/3 BUILDING Faxed Mr.. Jack Molver, PE J U N 2, 2000 David Evans and Associates, Inc. 1620 West Marine View Drive, Suite 200 Everett, WA 98201 SUBJECT: Revised Site Plan for Thoreson at 160xx-72°d Avenue West (S-98-1081 Dear Mr. Molver, The Engineering Division reviewed your revised civil site design. The review team notes the following revisions/corrections. Please contact the review team members directly for questions regarding their comments. Storm Drainage — Don Fiene Assistant City Engineer at (425) 771-0220, Ext. 323 • The drainage calculation report is approved as submitted. Please be aware that the 27year control is not required. I • On' sheet 4/6, there appear to be some conflicts between the pipe slope data and the invert elevations. Please verify. • Provide a profile of the storm system and show utility crossing to confirm that there are no utility conflicts. Water/Sewer —Jim Waite Water/Sewer Supervisor (425) 771-0235. Ext. 349 • The water meter locations must be revised to show them being placed on the -property line. • The blow -off must be placed on the property line. Install it in a box alongside the meters. The existing waterline and fire hydrant location is not as depicted on the plans. Tra c • There is no need for thickened asphalt edge and extruded concrete curb. The thickened edge and detail can be removed from sheet 5/6. When the revisions are complete, please submit three copies of the revised plans for additional review. A bond for $160,000 must be put in place. Forms are available at the Development Services Department. Engineering review. and inspection fee of $3,219 must be paid prior to construction authorization. If you have any other questions, do not hesitate to contact meat (425) 775-7744. . Sincerely, GORDON C. HYDE Development Services Engineer I. GCH/cmc c: John Thoreson; 15621-48`h Place West; Edmonds WA 98026 R:IENGRkGORDY18108a.doc Sister City - Hekinan. d6oan • CITY OF EDMONDS . • 121 5TH AVENUE NORTH • EDMONDS. WA 98020 • (425) 771-0220 • FAX (425) 771-0221 DEVELOPMENT SERVICES DEPARTMENT Planning • Building • Engineering January 5, 2000 Mr. Jack Molver, PE , U N 2 6 2000 David Evans and Associates, Inc. 1716 West Marine View Drive, Suite C Everett, WA 98201 CHR ON COPY -- BARBARAFAHEY MAYOR SUBJECT: Proposed Short Plat for Thoreson at 160xx-72"d Avenue West (S-98-108� Ste" Dear Mr. Molver, The Engineering Division reviewed your civil site design. The review team notes the following revisions/corrections. Please contact the review team members directly for questions regarding their comments. Storm Drainage — Don Fiene. Assistant City Engineer at (425) 771-0220. Ext. 323 • Per item #10 of.Engineering Requirements and per ECDC 18.30, the SCS methodology is required for greater than 5000 square feet of impervious surface. ECDC requirement based on this site condition is that the 2-year, 10-year, and 100-year storm runoff should be detained and released at predeveloped one-half of the 2-year, 10-year and 100-year rates. • Provide soil stabilization note. • Provide dike and/or sedimentation pond to protect wetland. Water/Sewer — Jim Waite, Water/Sewer Supervisor (425) 771-0235. Ext. 349 • The existing waterline and fire hydrant location is not as depicted on the plans. • The existing sewer in unopened 72"d Avenue West is'not shown. • Show required upgrade to the existing water line in 72"d Avenue West. • Meet Edmonds Fire Department requirements for provision of fire hydrants or fire suppression system. • Sewer service for more than two lots is required to be 6" with manholes at connection point and angle points and ceanouts located every 100 feet to the end of the line. Cleanouts are also required at the property lines. The sewer line. is to be private. ra tc • Per item #1 of Engineering Requirements, show required turnaround meeting ECDC requirements and show required dedication. • Incorporated August 11, 1890 • Sister City - Hekinan, Japan * Jack Molver, PE. * • David Evans and Associates, Inc. January 5, 2000 Page 2 • Per item #3 of Engineering Requirements, required minimum access is 16 feet wide.plus curb and gutter. Extruded curb is acceptable; however, a 12" wide asphalt gutter must be provided. Two feet of clear distance should be provided between the face of the curb and the face of the proposed rockery. • Provide a profile of the proposed roadway. Per item #3 of Engineering Requirements, the grade of the road cannot exceed 12%. • Show proposed barricades and guardrails as needed for traffic safety. • Show proposed location of driveway to Lot 4, and provide sight distance calculations. • Show proposed location of required fire and aid address sign. When the revisions are complete, please submit two sets of drainage calculations and three copies of the revised plans for additional review. It will be necessary to provide a construction cost estimate for City staff to determine the Engineering Division fees. 'If you have any other questions, do not hesitate to contact meat (425) 775-7744. Sincerely, GORDON C. HYDE Development Services Engineer GCH/cmc Enclosure c: John Thoreson; 15621-48' Place West; Edmonds WA 98026 R:\ENGRkCTOPDY\9108.DOC �. '' BARBARA FAHEY CITY F EDMONDS MAYOR 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 • FAX (425) 771.0221 DEVELOPMENT SERVICES DEPARTMENT InC. 189� Planning • Building • Engineering July 15, 1999 Bancshares Capital 22020 17th Avenue SE Suite 220 Bothell, WA 98021-8486 RE: Sequoia Ridge Project status meeting Dear John, STh�E�� FILE As you know, we have requested further information and analysis from the consultant before the City issues the draft EIS for public comment. It is unfortunate that the EIS schedule has not been maintained. Staff would like to suggest that a meeting with the key players from both the City and your design team be held, to specifically discuss what each side can be doing in the meantime so that the next steps will hold no surprises and the process will move ahead smoothly and hopefully swiftly. It is becoming clear that the earth movement window for work in the Meadowdale Landslide Hazard Area is closing fast and the potential for receiving the proper permits for 1999 is unrealistic. EIS completion, short plat decision, engineering review and approval of construction permit application, and subsequent buildin permit review and approval, cannot be accomplished before the September 30R Meadowdale deadline. This meeting is intended to identify what is expected from each side in order for the review and approval of the engineering construction and building permits to occur so work may begin as soon as the window is open again. If there is work that can be done during the wet months, we can discuss them at this meeting. If possible, staff would like to schedule this meeting for Wednesday July 21st at 10:00 am. Please let me know if this is a reasonable date that works for you. We would like to have your Civil Engineer and Architect working on this. project present at this meeting so they can hear first hand what items of the Meadowdale permit apply to their work. I would like to confirm this meeting with the other department as soon as possible but I will wait to hear from you before doing so. My hope is that this meeting will • Incorporated August.11, 1890 • Sister City - Hekinan, Japan i enable all of use to leave, feeling confident as to what the next steps are and what materials are needed in order to move forward with this project As I have mentioned before, it is imperative that you fulfill your end of the 3-party contract by establishing the City account to pay for the EIS consultant. If you have any questions please let me know. Sincerely, IKarissa Kawamoto Planner CC: Mayor Fahey Development Services Director City Engineer Planning Supervisor/SEPA Official building Official File NO. S-98-108 �V ,h� g 0 BARBARA FAHEY CITY OF EDMONDS MAYOR 121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 • FAX (425) 771.0221 DEVELOPMENT SERVICES DEPARTMENT COPY Planning • Building • Engineering July 12, 1999 S�Re�T FILE Geo Group Northwest 13240 NE 20th Street Suite 12 Bellevue, WA 98005 RE: Sequoia Ridge Pre -Draft Limited Scope EIS Staff Comments Dear Bill, Staff has had an opportunity to review the preliminary EIS received on July 1, 1999. There are several areas within the document that we feel were inadequately addressed and need further attention. It appears as if further analysis and clarification in accordance with the original scope of work is necessary before the City feels the draft can be issued for public comment. The following is a list of the major areas in which we feel the pre -draft was lacking: 1. The required EIS cover letter (pursuant to WAC 197-11-435) was missing. 2. A signed and stamped geotechnical review of the proposed home, road and storm drainage locations was expected. It should support the findings and conclusions made in the EIS. 3. The document conclusions themselves were unclear. The level of impact between the alternatives was not quantified and therefore staff could not determine whether construction of 4 homes with adequate mitigation on the property is equal to construction of fewer homes. 4. The no -build alternative is not one that the City can entertain without condemnation of the property and is therefore not seen as a viable option. The property owner already has the ability to build one house. The scope specifically identified option development of 1-4 lots. With the no -build and the one lot alternative being considered the same, the document only analyses 2 scenarios. 5. It does not appear as if the 12 "tasks" from the scope of work expected to complete the EIS were followed. Specifically, items 1, 4, 6, 10, 11, and 12. • Incorporated August 11, 1890 • Sister City - Hekinan, Japan Page 2 of 2 eo Group Northwest Inc. 7/12/99 Either the items were briefly mentioned with no analysis or they were missing entirely from the review. 6. It is unclear whether the 20-foot wide ingress/egress and utilities easement can contain all elements of road construction including the pavement, utilities, retaining walls/rockeries, handrails etc. A cross-section analysis and determination of whether the road can be constructed to meet the Edmonds Community Development code was not included. Maintenance of the road and retaining structures by the property owners was also not addressed. 7. It was unclear whether analysis of the impacts of surface water interception by the impervious surface over time would negatively impact the wetland and stream. 8. Staff would like clarification as to the dry season construction mitigation and whether it was intended to restrict it only to those months. We currently allow for weekly consultation from the project geotechnical engineer on whether the construction window can be extended past September. If that is not recommended in this case, then the mitigation does not need modification. In general, staff felt the document did not contain specific analysis of the 12 items from the scope of work. The no -build, one -lot and four -lot alternative analysis was not acceptable. It was difficult to determine the level of impact predicted by the development in the alternatives and how the proposed mitigations would help alleviate the proposed alternative to equal or lessen the impacts verses the other options. In order to maintain a timely schedule, we would like to see a revised pre -draft by 12-noon, Friday, July 16,1999, with issuance of a draft early the following week.. Please contact me as soon as possible if you would like to set up a conference with staff to discuss our concerns in more detail. Sincerely, Enclosure: Original Scope of Work cc: John Thoresen Mayor Barbara Fahey Ray Miller, Development Services Director Jim Walker, City Engineer Jeff Wilson, Planning Supervisor/SEPA Official Jeannine Graf, Building Official THORESEN SCOPE OF WORK The City of Edmonds has received a four -lot subdivision request for a 3.7 acre piece of property located within the Meadowdale Landslide Hazard Area. The site itself is designated as Environmentally Sensitive by the City and the applicant has confirmed that the majority is eligible for a Critical Area designation as defined in the Edmonds Community Development Code (ECDC) Chapter 20.15B. The preliminary geotechnical report describes the property as having an average 31 degree slope over 140 feet of vertical relief. A wetland delineation was performed and a 1.12 acre mixed palustrine and riverine forested, scrub -shrub and emergent Category 2 wetland was determined. An unnamed stream of Category 2 quality was also found, however, the City has reclassified the stream as a Category 3 due to the lack of salmonids. Critical Areas Ordinance Chapter 20.15B defines all three environmental factors as critical areas. Development is subject to additional buffers and building setbacks from the defined critical area boundaries. As currently proposed, the subdivision would require intrusion or alteration of the three critical areas. Building footprints for the four proposed homes, driveways (if any) and access easement would be constructed within the steep slope critical area. Wetland buffer averaging and elimination of the wetland building setback is shown, as is a stream culvert and driveway within the stream critical area.. The City is requesting environmental review regarding whether development of this site can be accomplished with minimal negative environmental impacts. Because the property is located within an Environmentally Sensitive Area, SEPA is automatically required. The SEPA official has determined that a limited scope EIS is necessary to provide the information needed to approve a subdivision that creates stable, buildable lots. Geotechnical/Structural The consultant will review the proposed development, site improvement (access and utilities) plans, construction techniques and options for future home construction to determine feasibility of development for each building site. Each lot must eventually comply with the requirements found in ECDC Chapter 19.05 for development. The installation of roads, driveways and other infrastructure as well as eventual lot development must be accomplished in a manner which maintains a stable slope within the definition of ECDC Chapter 19,05. Detailed plans demonstrating the ability of the proposal to meet the engineering standards for driveway slope and storm drainage will also be required. Analysis should also be made of potential impacts of development on the wetland and stream. Recommended mitigation and suggested construction techniques are to be included in the final report. Wetland Study The consultant is to analyze the proposed development and report the potential impacts the downslope wetland may experience as a result of the construction into the steep slope to support the new home(s) and the access drive. Outline measures needed to protect the quality and function of the wetland. Provide detailed plans and specifications on the proposed wetland buffer addition/compensation area. Stream Study Identify the impacts of the proposal on the Category 3 stream and recommend protection measures and replanting suggestions. The following items expected to complete this task would include: 1. Creation of development alternatives for the site, ranging from 1 up to 4 new lots. 2. Define specific building sites, if any, suitable for single family construction activities. Recommendations of outdoor residential uses (i.e. in ground sprinkler systems, swimming pools, tree removal etc) to determine site compatibility in relation to maintaining slope stability. 3. Determine use limitations of the home sites if necessary to prevent future impact to.the wetland and slope stability. 4. Geotechnical review of the proposed home and road construction for their ability to meet the City of Edmonds Engineering Division standards. 5. Review of potential construction techniques necessary to achieve compliance with ECDC Chapter 19.05 as necessary to preserve the stability of the steep slope environment. 6. Analysis of the proposed storm drainage plan for the development. 7. Recommend construction techniques and materials to safely develop the site without negatively impacting the critical areas. 8. Review applicant proposal for wetland replacement and/or buffer alterations. 9. Remedial measures proposed during construction phase to minimize environmental impacts. 10. Post -construction monitoring and contingency plan. 11. Replanting plan, including species, installation specifications for the wetland and stream. 12. Analysis of potential downslope impacts of construction to the wetland and stream. LS 10�� # I/DATE RECEIVED, 0 <91 �� '[PERMIT EXPIRES USE PERMIT CITY OF EDMONDS ZONE NUMBE CONSTRUCTION PERMIT APPLICATION JOB ADDRESS S, Itif�/APT# l I�/J OWNER NAME/NAME OF BUSIN S ,•,JC/>1'.l7'7/0s2e.Stnr PLAT NA2UOME/ 4 DI ISI N NO. LOT NO. LID NO. % 1C7 5 / � _ �ljt LID FEE $1;?t CC W MAILING ADDRESS TESCP Approved Q 3 c _ r �j PUBLIC RIGHT OF WAY PER OFFICIAL STREET MAP RW Permit Required,. )0 O / J L� /' Street Use Permit Req'd CITY ZIP TELEPHONE t%� EXISTING PROPOSED Inspection Required T/ _ Sidewalk Required A'O 0 �^ (j��yZ`� ��1; REOUIREDDEDICATION FT Wiringgrogntl �i ,"1 T 7 7 Unda re eaed yf� to NAME // METi-150" IZE 1 LINE $I /, NO. OF FIXTURES PRV REQUIRED O L) �`�N Z �2G�U YES NO ❑ w F ADDRESS REMARKS Z x /% OWNER/CONTRACTOR RESPONSIBLE FOR EROSION CONTROL/DRAINAGE yG� t7 a 4!� .. ��%/i� %fi/C a �i Exll�/N F7�r iJ%1 S/- f r.r :�n_i An- ' G� 7 �Ko ian w CITY ZIP TELEPHONE i ARA�Erwi iNF 9Uco �lf� FI ✓C?U/rt tl�f �+ ue A NAME S _// 38 i 2 �"r Irri6K-V route �s �,� a 'Or !� J ach v,✓ ENGINEERING REVIEWED/DA E IX S Cv ADDRESS Q ��9 � - �t zi ov FIRAZ4Mn Y DAT w o CITY ZIP TELEPHONE /�/,� r� LL / RIANCE OR C SHORELINE OR AOB# INSPECTION BOND STATE LICENSE NUMBER %► / EXPIRATION DATE /` r C1 ICKED BY:- ❑ RED'D P TE V S C�/ ✓ �� 4I\rW � I bC - D / (y//-I Xv YES I R A HEIGHT J 5 SEPA REVIEW- S GN A. E a PROPERTY TAX ACCOUNT PARCEL NO. MP TE ;EXEMPT«., ';ALLOWED PROPOSED' ALLOW PROPOSED W W J 6JT� Ex . _� +'.•-I�- �a �� .- �/ "'LOT COVERAGE,' 9EOUIIRED.SETBACKS`(FT.) ?ROPOSED;SETBACKS(FT.) M NEW RESIDENTIAL PLUMBINGJMECH ALLOWE =PROPOSED FRONT SI E-: REAR FRONT: .UR IDE REAR / " O COMPLIANCE OR ' l /0 w Z AUDITION COMMERCIAL. ✓ r] (/ (� Z / ❑ ❑ ❑• .CHANGE OF USE PARKING. . LOT AREA P R EWED B DACE' g ❑ REMODEL ❑ . APARTMENT. ❑ SIGN REQ'D PROVIDED a yy� FENCE ❑ REPAIR R��Dy �� CYDS ❑ ( X FT)` R RKS Ja2.LL I ❑ DEMOLISH ❑ TANK ❑ OTHER ` oQ..:� � ►� u P Z GARAGE 1�RETAI NING WAL L QIAP9R7 RENEWAL ' 4 AM ` Ma K 0 - F. (TYPE OF USE, BUSINESS OR ACTIVITY EfT a CHECK BY YPEOFCONSTRUC ION COD.`,' OCCUPANT i /".� GROUP U `/ W NUMBER i✓ MBER OF - - - CRITICAL %u, , m OF LLING ••� AREAS SPECIAL INSPECTOR {OA - - Z_ ANT O STORIES NITS -NUMBER REQUIRED YES DESCRIBE WORK TO BE DONE REMARKS t7 PROGRESS]NSPECTIONS PER:UBC;-a08/FINAL INSPECTION REO'D - v to - 0/�.S /iEPO/LTr9Y �i�O�C 3 gOD Z S-7&AelsrxuClLNL'13Y ARE1[rLLEw, E o PL n / .. .. VALUATION FEE 1.11,6/S AN CHECK FEE HEAT SOURCE LAZING % LOTS OPE1 ^T A-CCJ BUILDING v s%+ �JJ PLAN CHECK NO: VESTED DATE PLUMBING -300 00-- I MECHANICAL l THIS PERMIT AUTHORIZES ONLY THE WORK NOTED. THIS PERMIT COVERS WORK TO t- BE DONE ON PRIVATE PROPERTY ONLY. ANY CONSTRUCTION ON THE PUBLIC GRADING/FILL f DOMAIN (CURBS, SIDEWALKS, DRIVEWAYS, MARQUEES, ETC,) WILL REQUIRE �prY o SEPARATE PERMISSION. oW~fr 10 STATE SURCHARGE -fig PERMIT APPLICATION: 180 DAYS w a PERMIT LIMIT: tYEAR -PROVIDED WORK IS STARTED WITHIN 180 DAYS ENG. REVIEW FEES Ile5 SEE BACK OF PINK PERMIT FOR MORE INFORMATION U In 'APPLICANT, ON BEHALF OF HIS OR HER SPOUSE, HEIRS, ASSIGNS AND SUCCESORS ENG. INSPECTION FEE N Zn U W IN INTEREST, AGREES TO INDEMNIFY. DEFEND AND HOLD HARMLESS THE CITY OF L•AM999r4pfNG w-/ �/� Cr EDMONDS, WASHINGTON, ITS OFFICIALS, EMPLOYEES, AND AGENTS FROM ANY AND IN8PPr-TInfI FI;E 1&0 LIB//►'Yr Z (i� / Cr EDMONDS, CLAIMS FOR DAMAGES OF WHATEVER NATURE, ARISING DIRECTLY OR INDIRECTLY x FROM THE ISSUANCE OF THIS PERMIT. ISSUANCE OF THIS PERMIT SHALL NOT BE PLAN CHECK DEPOSIT RECEIPT o DEEMED TO MODIFY, WAIVE OR REDUCE ANY REQUIREMENTOF ANY CITY ORDINANCE r 7 0 NOR LIMIT IN ANY WAYTHE CITY'S ABILITY TO ENFORCE ANY ORDINANCE PROVISION.- REC IP •7 TOTAL AMOUNT DUE (J (/ 1 HEREBY ACKNOWLEDGE THAT I HAVE READ THIS APPLICATION; THAT THE INFORMATION qp LIGATION APPROVAL GIVEN IS CORRECT; AND THAT I AM THE OWNER, OR THE DULY AUTHORIZED AGENT OF \ / THE OWNER. I AGREE TO COMPLY WITH CITY AND STATE LAWS REGULATING CONSTRUC- CALL This application is not a permit until signed by the /J(\ TION; AND IN DOING THE WORK AUTHORIZED THEREBY, NO PERSON WILL BE EMPLOYED Building Official or his/her Deputy: and Fees are paid, and IN VIOLATION OF THE LABOR CODE OF THE STATE OF WASHINGTON RELATING TO FOR INSPECTION receipt is acknowledged in space provided. WORKMEN'S COMPENSATION INSURANCE RC 18.27. OFFICIALS SIGNATURE DATE R AG NT) DATE SIGNED (425) Z /p/ 'w 3 _ �-Cx7 771-0220 ` RELEASE BY DATE ATTi4TION EXT1333 IT IS UNLAWFUL TO USE OR OCCUPY A BUILDING OR STRUCTURE UNTIL 771-0221 A FINAL INSPECTION HAS BEEN MADE AND APPROVAL OR A CERTIFI ORIGINAL- FILE • YELLOW - IN PECTOR CATE OF OCCUPANCY HAS BEEN GRANTED. UBC SECTION 109 FAX PINK -OWNER - GOLD -ASSESSOR DRAINAGE REPORT SEQUOIA RIDGE SHORT SUBDIVISION EDMONDS, WA Prepared for: John Thoresen 15621 48" Place West Edmonds, WA 98206 425-424-3049 G� M0 v�;ti 20777 CWAL E ' ExPiAEs�,-------- Prepared by: DAVID EVANS AND ASSOCIATES, INC. 1620 W. Marine View Drive Everett, WA 98201 425-259-4099 RECEIVE 0 THOR0001 MAR / 3 2000 Revised: DEVELOPMENT SERVICES CTR, CITY OF EDMONDS March 3, 2000 DAVID EVANS AND ASSOCIATES, TABLE OF CONTENTS SITEINFORMATION........................................................................................................................................ 1 PROJECT DESCRIPTION..................................................................................................................... 1 EXISTING CONDITIONS..................................................................................................................... 1 DEVELOPED CONDITIONS................................................................................................................ 1 DOWNSTREAM CONDITIONS........................................................................................................... 1 APPENDIX.......................................................................................................................................................... 2 DRAINAGECALCULATIONS............................................................................................................ 2 SOILSMAP......................................................................................................................................................... 5 EXISTINGCONDITIONS................................................................................................................................. 7 DEVELOPED CONDITIONS........................................................................................................................... 9 BASINMAPS...................................................................................................................................................... 11 DOWNSTREAM DRAINAGE SYSTEM......................................................................................................... 14 Targeted Drainage Report Page i Sequoia Ridge Short Subdivision March 3, 2000 SITE DESCRIPTION PROJECT DESCRIPTION A four lot subdivision is proposed for single family residential development. EXISTING CONDITIONS The 3.66 acre site lies on the south side of Meadowdale Beach Road and adjoins the west side of the unopened 72nd St. W. right of way. Vegetation consists of second or third growth forest with dense underbrush. A small spring fed stream runs along the northerly portion of the property and enters a 12- inch intake near the northwest property corner. The site is bounded by residential development to the south and west. A hogsback ridge, which descends from south to north, runs along the west side of the property. Soils consist of Alderwood gravely sandy loam. Some Everett series soils may be encountered in this area. DEVELOPED CONDITIONS ' Four residences will be built along the ridge line, set back as prescribed by the city and geotechnical engineer. Three of them will be accessed by a private road extended down from the existing terminus of 72nd Avenue W. The fourth will take direct access off of Meadowdale Beach Road. The drainage from the site will be tightlined and routed to an underground CMP detention pipe. The 80', 84" pipe will detain the developed site runoff, discharging the developed 2-yr storm at 50% of the predeveloped 2-yr rate, the developed 10-yr storm at the predeveloped 10-yr rate, and the developed 100- yr storm at the predeveloped 100-yr rate. The resulting discharge will be routed into the existing system under North Meadowdale Road. DOWNSTREAM ANALYSIS Upon entering the enclosed system in the city street, drainage crosses the road in a 30 foot long 12 inch diameter culvert and connects to a type II catch basin on the north side. Drainage from most of the road and from the tributary drainage to the north enters this CB and is carried north about 105 feet to another 1 type II CB equipped with a flow splitting device. A minor amount of the flow to this CB is discharged to a natural ravine which flows to the northwest. Discharge to the ravine is by means of a 6" CMP. This outlet is equipped with a "FROP" tee, and the lift gate is currently in the open position. Primary drainage flows down the road in an 18 inch diameter culvert to the intersection with 75th Pl. W., then continues to the southwest down to the easterly margin of the BNRR right of way. This point is about 770 feet downstream from the proposal. This enclosed drainage system then turns to the south and parallels the BNRR right of way a distance of about 510 feet where it turns to the west, crosses the railroad tracks, and discharges into the sound just south of the boat house dock. Targeted Drainage Report Page 1 Sequoia Ridge Short Subdivision March 3, 2000 I APPENDIX 1 1 11 DRAINAGE CALCULATIONS Detention will be provided by an underground CMP pipe sized in accordance with ECDC 18.30. The 2-yr developed storm will be released at 50% of the predeveloped 2-yr rate, the developed 10-yr storm at the predevloped 10-yr rate, and the developed 100-yr storm at the predeveloped 100-yr rate. METHODOLOGY & ASSUMPTIONS • SBUH METHOD AND SCS CURVE NUMBERS WERE USED FOR HYDROGRAPH GENERATION • THE "LEVEL POOL ROUTING" TECHNIQUE WAS USED FOR DETENTION PIPE DESIGN • STORMSHED SOFTWARE (FORMERLY WATERWORKS) WAS USED FOR HYDROGRAPH GENERATION AND DETENTION DESIGN • 24-HOUR DESIGN STORMS WERE USED AT THE VARIOUS RECURRENCE INTERVALS LISTED BELOW WITH RAINFALL DEPTHS FOR THE EDMONDS AREA INTERPOLATED FROM ISOPLUVIAL MAPS OF 24-HR STORMS • WEIGHTED RUNOFF CURVE NUMBERS WERE USED FOR DEVELOPED CONDITIONS AS ALLOWED BY DOE, FOR CURVE NUMBERS WITHIN 20 CN POINTS OF EACH OTHER. • THE SCS SOIL SURVEY INDICATES ALDERWOOD GRAVELY SANDY LOAM AS THE SOIL TYPE, THUS HYDROLOGIC SOIL GROUP "C" WAS USED FOR COMPUTATIONS PROJECT PRECIPITATION DEPTHS [6mo] 0.99 in [2 yr] 1.55 in [ 10 yr] 2.25 in [25 yr] 2.60 in [100 yr] 3.25 in HYDROGRAPH DATA BasinID Peak Q Peak T Peak Vol Area Method Raintype Event (cfs) (hrs) (ac-ft) ac /Loss PREDEVELOPED 0.04 8.67 0.0369 1.30 SBUH/SCS TYPEIA 2 yr PREDEVELOPED 0.13 8.17 0.0832 1.30 SBUH/SCS TYPEIA 10 yr PREDEVELOPED 0.31 8.17 0.1634 1.30 SBUH/SCS TYPEIA 100 yr POST -DEVELOPED 0.21 8.00 0.0845 L 0 SBUH/SCS TYPEIA 2 yr POST -DEVELOPED 0.40 8.00 0.1499 1.30 SBUH/SCS TYPEIA 10 yr POST -DEVELOPED 0.69 8.00 0.2496 1.30 SBUH/SCS I TYPEIA 100 yr Targeted Drainage Report Page 2 Sequoia Ridge Short Subdivision March 3, 2000 1! APPENDIX DRAINAGE AREA: PREDEVELOPED Hyd Method: SBUH Hyd Loss Method: SCS CN Number Storm Dur: 24.00 hrs Area CN TC Pervious 1.30 ac 81.0 0.40 hrs Total 1.30 ac Supporting Data: Pervious CN Data: Second growth forest 81.0 1.30 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Initial sheet flow 300.0 ft 35.00% 0.40 23.65 min Channel stream 200.0 ft 7.50% 23.0 0.53 min Tc = 24.18 MIN DRAINAGE AREA: POST -DEVELOPMENT Hyd Method: SBUH Hyd Loss Method: SCS CN Number Storm Dur 24.00 hrs Area CN TC 1.30 ac 90.98 0.19 hrs Total 1.30 ac Supporting Data: CN Data: Impervious 98.00 0.54 ac Landscaping 86.00 0.76 ac TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Shallow Shallow Flow 300.00 ft 35.00% 0.150 10.79 min Channel Pipe Flow 400.00 ft 25.00% 42.00 0.32 min Tc = 11.11 MIN ' DETENTION PIPE PERFORMANCE DATA 2 yr Match Q: 0.0182 cfs Peak Out Q: 0.0186 cfs Peak Stg: 178.40 ft Active Vol: 2814.92 cf Pipe length: 85.00 ft 10 yr Match Q: 0.1289 cfs Peak Out Q: 0.0994 cfs Peak Stg: 178.46 ft Active Vol: 2842.34 cf Pipe length: 85.00 ft 1 100 yr Match Q: 0.3108 cfs Peak Out Q: 0.3139 cfs Peak Stg: 179.23 ft Active Vol: 3150.64 cf Pipe length: 85.00 ft OUTFLOW HYDROGRAPH DATA HydID Peak Q (cfs) Peak T (hrs) Peak Vol (ac-ft) Cont Area (ac) OUT2 0.02 24.17 0.0695 1.3000 OUTIO 0.10 11.50 0.1350 1.3000 OUT100 0.31 8.83 0.2346 1.3000 Targeted Drainage Report Page 3 ' Sequoia Ridge Short Subdivision March 3, 2000 APPENDIX CULVERT Desc: 84" CMP Detention Pipe Start El: 172.28 ft Max El: 179.28 ft Length Diam 85.00 ft 7.00 ft (84") MULTIPLE ORIFICE CONTROL STRUCTURE Descrip: Multiple Orifice Riser Orif Coeff: 0.62 The pipe control structure will consist of a Type 2-54"diameter catch basin Bottom Elev: 171.28 ft with a 8.5 foot, 2-orifice, 12" diameter riser inside. The riser will have a Outlet Elev: 173.28 ft restrictor plate with a 9/16" diameter orifice and screen welded to the base Max Elev: 179.78 ft (Elevation = 171.28 feet). The second orifice with a 3-7/16" diameter will be Lowest diam: 0.5500 in at an elevation of 178.40 feet. The top of the riser will extend up to an Outlet to 2nd: 5.12 ft overflow elevation of 179.78 feet. Diam: 3.4500 in Targeted Drainage Report Page 4 Sequoia Ridge Short Subdivision March 3, 2000 1 I I SOILS MAP � J 1 1 1 II Targeted Drainage Report Page 5 ' Sequoia Ridge Short Subdivision March 3, 2000 RIM- PRIv RA fl. �'V `�< k• 'may x? sra Mir ke F Oil ✓�, it ,' r, ,t n. �x wry; p� � _'� s� � ��M�✓S�'?"t;��' ,`d �� „Z: ,� F,ys.'+x - r�ld !1 �".i'�'�.. lrr.E• '�„ D} t ',w �... } � r v �� W S�� t h l4 p •� 1 J� "i � �i'r 7' r t- !'L .. F. �1.1y -'. � M, 1 i n L 1 EXISTING CONDITIONS O Targeted Drainage Report Page 7 Sequoia Ridge Short Subdivision March 3, 2000 r 1 11 F 1 r by CATCH BASIN /1 TOP 225.60—mac yy N 30 4b' '\ � EXPOSED 12' C-P IE 296.24-9" lur zn.oz � 210.89- ,,. �•�.•� / SS MANHOLE - SD SO Sd TOP 219. 50 SS - IE 209 52-8' - _SS55 / ' / �, f . • .. .. pP TOP .� BANK CAT ASN TOP 215.40 /;�% 40 GARAGE it I TOP 202.08 3 / %/ / / / /. /, 4ti_ / •/ �.)�/�` SS MANHOLE f I92. E 10E -FP IE 19194-8'W CATCH ASH TOP 197.71 i' i \ / / / /. / 'L2 / �' Y� ' / GARAGE WATER MANHOLE (PRV)00 • /• T ; ./ /. \t;�'°' _ 2 I /f�. / J /a 7�b / /. /, / /•YY LAWN EX HOUSE ) /.Av� d yy v�/ IE�168.81 (CP) Ny N CAi BASIN / y17 SS MANHOLE \ \ OP 150.79 IE 143.09-8E Iw SW T.o 6 .\ N I LAM VA �,`v� BANK SO BENCHMARK INVERT OF SANITARY SEWER MANHOLE AT N.W. CORNER OF PROPERTY ELEV. 143.09 DATUM: CITY OF EDMONDS LEGEND ❑ CATCH BASIN 04 WATER VALVE M GAS VALVE UTILITY POLE w/ GUY WIRE TO TELEPHONE CLOSURE OOCbD ROCKERY X-X FENCE O SANITARY SEWER MANHOLE fi FIRE HYDRANT ) —SS— SANITARY SEWER LINE --0P— OVERHEAD POWER LINE —SD— STORM DRAIN LINE —W— WATER LINE --�— EDGE OF ASPHALT H HEMLOCK OF DOUGLAS FIR C CEDAR S SEOUOIA EXISTING CONDITIONS 1 11 11 1 r 1 I 1 DEVELOPED CONDITIONS � Targeted Drainage Report Page 9 Sequoia Ridge Short Subdivision March 3, 2000 A PORTION OF THE SW1/4, SECTION 5, T. 27 N., R. 4 E., W.M. y� s CONSTRUCTM NOTES 1D41 O CONSTRUCT PAVED EMERGENCY VEHICLE TURN -AROUND AT EXISTING PUBLIC = c. ROAD END PER CITY OF EDMONDS STANDARDS. _ r::.: ;7.;., I O2 MATCH EXISTING PAVEMENT EDGE AND ELEVATION. y/— O3 INSTALL STORM DRAINAGE DETENTION SYSTEM PER DETAIL 5, SHEET 5 OF 6. - A HYDRAULIC PROJECT APPROVAL FROM W.O.F.W. SHALL BE OBTAINED FOR :['•�`'" -s CONSTRUCTION WITHIN THE STREAM. Ll 7bd AVENUE / W / ( / _/ ( — _ J —� �• '-,(NOT OPEN) / j_-._*,I-._—.__�.�/vLw°�1ti-�"'"" O RESTORE STREET PER CITY OF EDMONDS STANDARDS. q// / / OS WATER SERVICE TO LOT 1 TO BE INSTALLEDBY CITY OF EDMONDS FORCES AT TIME OF HOUSE CONSTRUCTION. I I—T'7 T• O6 PAVED ACCESS ROAD TO BE USED AS FUTURE DRIVEWAY FOR LOT 4. („ /4 // ,-,�- \ / // / i / / $,•�/ // / / / O7 RESTORE GROUND TO PRECONSTRUCTION ELEVATIONS, iJ` / //,y // / / / I �/ / // / / // 5 / �•� c/�i ' �•� O off`' 8 INSTALL W.S.D.O.T. STANDARD BEAM GUARDRAIL O9 INSTALL FIRE DEPT. AND EMERGENCY AID ADDRESS SIGNS FOR \ 6 / • / �// \ \ / / I r I I / / / / / / / / / I { \ LOTS 1, 2 AND 3 WHERE SHOWN. iv l EXISTING HYDRANT�� 1 // // I/ /% 1 / // / // / NO N i ES $ EGTE55 i' IQ / / / / / I UTILITY EASEMENT 11 =A- 5I 0049 IN TGP.,eR50 CONS POCT OVER EX a SS G/E.: III E-,7157-IEN I 0 \/ / \ // / / / 2 C e - TYSE.E DO 8-3\ -S T1P INSTALL AT END 6 1 CP (RATE-1 E-17L91 EX - lY NEW iE=17 . 1 CATn 9A4N i[TC ' GA9 [A T[i BASN 4 N J• CF T.91 N by AtcN @ASN T � E�17400 A- E-te100-4 351 17 _;° / C OFy(YOP/ TOP [ • 25000 D 4A� SO � 7pP aAN,f � / `, S 17.5 OF A. 1 LONER TO EX ev,N ,-1EX1ovE oosnec PWG e THTUST TAAGONc 1-Y GTE YAl`E (YJA) + i-r aor-GIY AsgueLr 1-� FLTIC rya) ( TNIp15T 8L0001G z s J AL 9 in lz _ c t <° 0 ACC 0: � O c W y W F- i z g _ d V 0 t ` 1 APPROVED FOR CONSTRUCTION z s Ott OF EDMONDS ENGINEER GTE q p a 4. BASIN MAPS Targeted Drainage Report Page 11 ' Sequoia Ridge Short Subdivision March 3, 2000 `%'�. � "'�"'!`'u.e!�»�' < :;tfF u. . T Jr R°°`y:'�; ,r ry �dC>, '. y: , `'0 '' i � ^A•*i?E?'�.'"•`•5 'r41 ¢' '�x� 71K •'.'t'"3:."'+w...�;3 �!<e r !y<- <fa:S' c.✓ "5!!!IP >,%<y :/:/ 1enj"ot..''�,"••nor ,�'<;, <t yAF < ;,� ♦ , tiN` `!J7�4. yy. :Q' !'r �,, �3•^fo ° 'F.^ J,i,M r., '<�OC�`A �' b' > <�'�". �Mk•.r...y." .<>L .,C.i�°t :Y' v s: mow: ',F � Gt rn n,? � i'fl�., y, :?mac �.fit .0 '\ <y t `µ.. w ,.� � Q •a O o' ffr ! ', A' ... �- /< A> c ,'iay��r� s 2' Yon y �'�d,�e' r � xf d c �.; i �" •'� , - /Giy ",; - t;'°S•.'': . .. op.J• .Rowx �x�<• 7 X z t � Y S :•. rrr ,69gf,Q o.,,,f '> ' 4 "f`F,�4'vi<'3; '/.rT9' lC�,•< �R. '6' d �• J Y' � �X'zo!•!r< f<E°Z a•o�a OD01— LO war r �,�" ""•,< ry, CC) Yx w 6/ x s cr O>t` > ¢<4� 10 ts 4' goµ /! ', . __,� —� !1.&>' ^ ,�.....••-""'� ,..... a • \ y¢¢5v�,z.. �4,� �,;.A » a T - e . •' < ..,fN•,/N A ro, Xto s„ .,,6 • •' ,y�,ee, ••,xv^� ' ate•, � ,� ,. £ � � � ° ��rC� � � � �� ^ � 36i• °,� cn A::z _tli3� x f :,o" `.r,.., LYi�; ., Pc v �< f .2a. „$s'•, �� • f� r..c0%fN < 'xVr^>,.-__ row',. q l�,S � ,S RY' � JKk'ad°�S V h,�>��'Y,�.,bC�, �� ° Z:•:� �. �F / Y,•�`.,,..�.�,�• � yc ! R . % v^ rQ r J ¢ ff ,,,� r f, �,y,� t% c � k f ,2J r• "72wJ> ��• Beebe;,;; /.r "% `Co /R�r; r- y fA� �6 ` c •z<� vkr �k jrYl wM Ilk.: J.�!£ : �. e F <<¢>i i•<¢so„GiE;; w �. ! gy°. .Gs's bt '.,,, 4,z S••,.•:',. `',z'a�`' f(.,y V./ <,r' I ' � y r f �� RY» z�A \ `2•k?t. � , � cK, - ,J ' �, � fr : `�s`•" � "°6 ��.`'y'�a�� `w � � ` cA c ��`p �?'�°`f � / awr . �k•T°'� J r �' < w r. � t• ��` yya, °ao£ . � �' 'tt h i r, ... �� •t�yFy <- \ w..': , s t �'f R' v I �� < < �`".. � j{),��a > .CaMc<• < �,V . 'HCF" � % ' ,Ae RY � <.R"'° Y R,N�! ie,. �i '• T. da .+'' � .}4i ' a,'.;`bo, ,. � �,3{ C .,° � lhii > :C oy'<,C „y x �.. < '• '•r� ,'.�' pc• �+S \ � � o > x ,f�� s, . � �'., .��>• ,. �^' ::`x, f ,� xy ¢ !� °' R ie `f4, �ut'ieq.� .t,^ :o&t�:. �� .' }•, '. �_�. '%. `vy, Y'?•%jk10'.c•. '. `"t :3�o'g " 'o � ,C ', /A' a¢'••\�,,.,; ................00• ^^^`"o•'� � '" 'C 9 Atf� 3 r< ' w`?'�O /� � / 1 S'' 'E � yi:. °• °�' 4 ,> i f I r/Jr` , / o�n" • ! f Y• y 'A y 3� x x� Ar„` r¢z�'�'`'� .X,� . �k � 3S z � '' :i. � ec@�3° ,.`, °'fY."•.� � �`•z`:.Y.�.;,/ .>:' f f • ° ..3j tC Pik r.. d�:', f < �.�..,,�/ . � ,,•,../ { � �,.N � < '�""' :.:mw;x >,.3Y � a >' ' c �� ` `� t;; .aFcy � n ti , >0` ve,•�� "< ,: i. i is s '�+r�.". ^�J'� �, �? 4<i'0� F 3 a> S<� K•c ` ¢ `:�Y' �,�:%s �3�'v� ..» '�'inz� �`�-.«�✓�',[ .,.fit 4t�..s y� : �,� ' J ` v.. � w.er .':Y"w' % �F �4K'i • �� f Chi' 7`.J ' , t < ' �? ' �a3;'9 oQG1' `6Ro,��fjp➢/u zui!' z �, •�, � A ?K,.. ,, " 31,ee•�•,• .ee r:r�A'�' `'..'►..�,.. os� ^' J �•^ ."'^-� �F , mot"" ,xL O S!0Y /� "�,y . �' � ^!i ' By. , Mr,•.w.•.r,!'."'<<7'L'tli�� 'k7h $) '� � k.,, . '. r.: "� � :. •"s�keyoc ° 9\ox, ;� `••+r"""•`.r ,,.° R,o�i, .: �. �' • R\Q'T'. eeo. ¢ R.y, a• -yf :: !. E�„ •s: y ^ ,�: w .`p Ju.. y;'< ,rkv- "�'. a.« I DOWNSTREAM DRAINAGE SYSTEM Targeted Drainage Report Page 14 ' Sequoia Ridge Short Subdivision March 3, 2000 m 15714 15631 ^ 15709 15707 680118 in —i 13722 1-156 1371£ 68M 1-9 1-119 1372! 13729 1572B 15724 < A l37e3 h 15720 i I -t3l 1-144 43 - 15732 1 `� 158TH 1-142 1-140 1-1 157-V , 1-166 1-150 7400 1-2 SB10 PIE Zl] 1-141 15808 ( 15814 15821 ru� 24 W 15914 13800 - 49 i 15809 NO�TI-� ' 3 1315810 824 i-128 = 13818 1-7 l „ + 15812 1-t4e =zoo' 15924 CD 1-27 lS�J 15926 13828 1-5 l5908 2 15B27 �� 1=146 1-31 1 -3 15904 } 3 t_ o..�. 5 ►T 13902 1-4 1-29 2 15911 l3907 J 15910 1-27 a` 15910 Q 5906 N 1-174 Z t-19 1/2 15" 1-178 159r79 13912 1-26 -76 CU 5.9,17 15915 PIEZO 7309 — 15920 1-19 1/4 13 r.oti o d .A-T-2w � E..1E1_ 1601A0 1' 1-79 1-791-77 �,0 1 1 2 „ ( 15926 6911 1_16909 13920 1-3 1-74 1-24 t-21 1-n 160TH T SW 1-t -231-22 1-81 16012 1 2 1-73 13931 1612! Eis'20 - 1-33 600 1600 ` 1 85 3 16008 6970 6910 t 1-84 16010 t-tt2 160P4 1600 12 N 1 ` Z 1-87 1-36 > 6 916 826 1601 6031 6010 ! 00 16119 16115 16020 I -to 0 I 1T' 1-171 11 1-71 6960 692D r 3 ,6038 161 16109 1-134 t- 33 1-11 1-111 161 �- 1 v� 10 t-170 1-70 68LT9 l611! GRND v ER , 12 16209 6919 f� 6803 l51 69I2 1ra7 SYSTEM L-1 t-169 CM 6944 6 S T P 16l0 1610 t � 1-92 1-450\ 1-584 16100 -6 16215 1-133 I 6804 t_� ' 16115 4 611 1 8 -137 1-136 0 16131 6 6121 6J22 (Z ' P a/c— 6217 I MIS bi .1-43 t-175 ND WATER 1 1 38 / ' 1 1-89 1-44 IMTE TOR SYSTEM ; Q t-90 1-08 �' 16202 16209 16216 �, i A P ZO I621J 1-161 -101 OPCN SPACE �Q' T BE '� 16209 Q 6P31a4 1-35 69e5 I 1-13 ' 1-41 Q 1-� 16213 1-a0 660! 16220 2e0 _87 16522l9 6923 t-t4 16310 1-39 1-53 162P3 1-100 6805 t-102 163e0 16238 !� 6224 16228 '13 1 1-39 1-163 ` 16225 69e! 1622e 1 27 1-99 1-103 16232 164l1 t-31 1-16e 1 6908 t-l5 6317 -919 1-104 1 16330 199 6915 6802 �- 1 ~ fLi t 64 ►� l6318 16315 16320 1-177�1�� 16319 ` 63 6�6901 9 16404 PI ZO TUIE r-Lp�.i cv LI l- 31 163 1+-93 7 4 0 l-% -180 16429 a ', 7109 16323 16322 l6321 ,P 1-1 �_ 1-t79 1-34 1-30 1-47 1;94 1-93 6904 A ki �' NA9 S-98-108 Col— WAS- 20777 I . . . . . . NAL FE�P71RES -7 -Z 6. CITY OF EDMONDS WASHINGTON R r:. aE g V F. D SEP 2 8 1998 PLANNit"i DEPT. THOR0001 DAVID EVANS AND ASSOCIATES, PROJECT DESCRIPTION A four lot subdivision is proposed for single family residential development. EXISTING CONDITIONS The 3.66 acre site lies on the south side of Meadowdale Beach Road and adjoins the west side of the unopened 72nd St. W. right of way. Vegetation consists of second or third growth forest with dense underbrush. A small spring fed stream runs along the northerly portion of the property and enters a 12 inch intake near the northwest property corner. The site is bounded by residential development to the south and west. A hogsback ridge which descends from south to north runs along the west side of the property. Soils consist of Alderwood gravely sandy loam. Some Everett series soils may be encountered in this area. DEVELOPED CONDITIONS Four residences will be built along the ridge line, set back as prescribed by the city and geotechnical engineer. Three of them will be accessed by a private road extended down from the existing terminus of 72nd Avenue W. The fourth will take direct access off of Meadowdale Beach Road. An oil water separator will be installed at the end of the private road and drainage from all of the impervious surfacing and yard areas will be tightlined to the existing storm drainage system in Meadowdale Beach Road. DOWNSTREAM CONDITIONS Upon entering the enclosed system in the city street, drainage crosses the road in a 30 foot long 12 inch diameter culvert and connects to a type H catch basin on the north side. Drainage from most of the road and from the tributary drainage to the north enters this CB and is carried north about 105 feet to another type H CB equipped with a flow splitting device. A minor amount of the flow to this CB is discharged to a natural ravine which flows to the northwest. Discharge to the ravine is by means of a 6" CMP. This outlet is equipped with a "FROP" tee, and the lift gate is currently in the open position. Primary drainage flows down the road in an 18 inch diameter culvert to the intersection with 75th Pl. W., then continues to the southwest down to the easterly margin of the BNRR right of way. This point is about 770 feet downstream from the proposal. This enclosed drainage system then turns to the south and parallels the BNRR right of way a distance of about 510 feet where it turns to the west, crosses the railroad tracks, and discharges into the sound just south of the boat house dock. Based upon the attached drainage calculations and the assumptions therein, and assuming that. the system was properly installed and kept in reasonable repair, the downstream system is shown to be adequate to accommodate the undetained flows from this proposed development. 0"S TCH BASIN CATCH P 154.76 TOP 167.16�YA"... f I.E. .81 � ss � (N� -Op �y0 / .. C T A IN `� d ^� TOP 171.90 i 3� ,.� S CATCH A IN I.E.OP 171.90 WATER MANHOLE ECP 158.9� r �^ � •Ty,�;� � (PRV) > SS MANHOLE EAM BUFFER TOP 200.74 IE 192.09 8 N C T li BASIN IE 192.04-8"E 2. r 4 TO 197.71 IE 191.94-8"W TF /n O 15 J \ ly CATCH BASIN I O \ Ir TOP 202.08 r \ OSED •D�� # •' �, „ K' ---EXISTING HYDRANT cj DI�Z�X SS F^ T IN N�f O DP 26�' ti�\ ,��¢ ry0o, I TOP 215.40 ,222`SF/ �. _ 9�\ c� \ 0,9 SS MANI �\ \ \ h S �F TOP 219 \ C�l T�YP I�0 pos ,�6 ,,o•E _ _ �¢ 40 STTtEyAM AND \ IS s3 25' STREAM BUFFS WETLAND BOUNDARY p\P'QGS.1 �►� ��52,248\SF \ \�oo \a5' SEME T FOR \ \ DR� A \ o IDS WER C cn 51222 SF DP 6.i 5 9 u7-�p5�'\ S � N 1 �Q3 Ml 011�U. %t��R 'n I f 4-1 E 260 \\ \ \ -Als \� / \' CATC BASIN d i BSMt'2% \ \ \ N a�1' / \ '� ( g TOP 215.19 _ 1Lo 46,891 SF \ `JEANINE L.CA' \ � --CATCH W PROPOSED —+F• i9Q. \ -- / TOP 224.3, HOUSE O �J \ \ \ \ --� \ " \ \ / / I�OCATI ON TYPICAL) \ 3 / �V. S9,1PLEANO 41 _ `� EXPOSED 12 / \ \ N (OUTFALL SYc `\� \�\\\\ \� `�\ �.\ // WESTMONT F��Q8\ \lcv —I o n D4 Napo ��` \� \ LJ ✓ — ��- z \\ lcv < N89'38'04" \ IN, \ 122.07' TOP OF BANK G EGORY S. Ci JOHN L. JOHNSONcv r� EDGE OF ASPHALT TOP OF \ "1- BANK v 4 C Co�c AL Df_-Vf_,L0FV.FtJ_F 09) N X N G H .4 N v WA. i 17. PO Y I., 1 ilk 'VIA � 1, W.W. A INK Its- ZE ilk Z1. NR Vfrvy NU . . . . . . . . . . �11 MIWAMIM�W_ y _ ... •drS .6 'P:.. 'Y:' `~ :. .:k y is t w „�. n 4t w ( a6•' /y wt.<?. � 'fif �S:yO 9° 6r=> c > ,c, �¢>y`6;yY r : yg =< > aS' .� n� K �Y'T p,t>�tri;•9. �¢ /�� c, � /i t �w ., �� `''�@Ys? ,.>. r ri a % �`�' �'�'sb°)` '0S'` )r Y :. x S ..:Jr •y'� ac r) >' °'c�':c' `r%f7r �d }T, �h q. c �` i 'r4 Cy^.. \ :.pit* :•^:'- qo r J'ti,.,c r SF� s :.: .:..'> �tiati' ,.'� �.�pli► y,c < c /`°. ,.. r'<'• ti ^�: >�rha �<: ' «i, <cf =N»S�:.!. •^. °�'..,,.-ior%Cq�'; ;aa r< .:`w'y?>,A<• ,;'- 6r+.'y:• .:::F3'•,,,'W. ^ry, ':r'•."", '•� '•'.>'?" ,.°h::.."�k.w^n,�<• F%r .�,q v..(�, �;c Aa vS,; A. ,�;. N vk, ; '*.Am •wo iyr��r� a .aa Y> r '_` A i �:. x e^, a , %<> < - i'vy •ram 1 ° > c a°LES?`q >' y €•yyi ..` twi:'M>''', �•'(� 1 J {i�r S •,.� ?�P 8.6:. S`k ¢'rc`., � <;.,� S t? � ,' tt�-a*! Mq'' \,v t' w"rp` .•>:�>.s> /' f' \ i�o t c '°Pxy r< 6:. •.5� P <Sa`,rF=;.r T , N Z q .�' ry,yaes Y W < aT ` So , G irr ,� rea^ev'c !• �, ' Q a r x t vi P � <ov J w<.?oj r; yw , J � � c c iA a � , Z CooY . I r OD J \V; ` ^ °. _ ;s /c"+/r`•ni r r � s �Ts )/,>uF r L• xe`r \ ya. ; tia on ) d �%`' L. K 1t /h L<°t' ) - �'. ` 6>:. >�b • »i). r',(' ;. r w%bk rf. iN.•a r ,,s, rf >'t� c y 2 v •'s.�\�� t'e'!"':'r JeL� �::..w y «°`r, ""obrO M�'.R r y %-"'e ` > o.>'".s�'�it'Ae%:✓,v4 �'Q1 ,x, 9s K ,.:/Cie% d�f < a, c' •4 �` y3 •',� "�`•e ,• �':'�ttea i'�.,r: -::. ;• .fcc ffi ?aY;u vif d' r `w'!.v �x -. w' '`SR ve x'- Xf ^�•� ems" �C�, qw ,�seea. I� %;vya1 : ✓,.�:,F dcY i.:- ,,y t.A J a� c - % y= es$'Y,�t'4„ys, f fh Lfl' rrb:iY ix yF'�% S rx<v` n c «kx o v""dte 'ski r :. i'li r <^^,'' ..:r :fig x w r yAy♦ r X ; _, > 9 ryy ' w ».. y, ,a, 'r3 Pc,,�>.� ey. o S "• o«¢'sc•Jh Aa ;ik ? �' yX'i :fig 1 >'<: '�� ^>t l°iF �6yad').. x'�2�.:r a i % X , �S' ^ ` f nc 0 A•r` a 'ts i) � ): n „Lf \x F< �eV>r w° vRwQr Ly% )?<�qr � ) 1 °ofw YS;> z .4 ••:c t c c , � '�4fe b= :'rr y: PFa, L=Z� o �"v, ..>� ,Ri` a t . .3'rT>'i)L E> c,C, r n ; ... w< c.:/,<' <?'zb �o,° c r r �i`d,� '''y s v 4e RnfE `tw'L c, t o,ha <:,Y`s•,';< Ys..•.... ;, • rl Y •� rt `..i ii N yo9 ,`i,G 4 , ,�.Y= , „k k, . ..... �"' �'7 .. •� :: y P :s? " .� n�. ti' > y .ay;,. ^ Su,\"�•`.c '2' q P ri\ '` yr p i, c �5•'(S � s.:.X r � ua s r P '. .. _ . _ _ _ - S, at% _ ^ ..• s< c c r' Y• .:i. <w Y%y ^ a S R .z�• 3 f,.o '3 yP _ » attJ 1. fy : y - � - - - �- � - - -• u) ''rv"•L e' k J )'<h bi "^.s ' .o' -F+7 rxoP- ; < N -. "S >, h y R/ r'� - 3' o•:; y, c� cfs . i \_�a' Y'b(i ' .g• ': r i i . S - M J ; � > >x, at w'"<x "y"' ,� `>Axc °•"' !Y C � o A` y�r � f'� ia, %S to ! 'YS'2' � � ..... f'�.•'F? S< ,> w+ Lri�`Ja, <:.,.„o X , P`Ar ,x �� ^6`' � \�+, h �s ':.' <,.. � .��„/ < o q, : T1 X S: ? h f ,i�'w, %ti^' Y taJ,�'o 'Y• ? '� a Ny \m >j"�. , 'r r � a� � £: ;. i�.YFr,y '.. %) i. a <{,, : +�✓ t ,x,' y �5S:: MR L/ Y, Si<,Sa ,Va, y rcc°�ara ;'??' �v � �6w fercr°�tay �.: s'j R' � �• s - 5 f" r<+? � �) }i> 'T\ >.v�1<y�� yJf`. ,)rJq c^` ./ r <�: .+ ,00i« � i� 'c1�� <L,tiY.�'' - r ,>•>A9;y�•,; � b `• \ a "?' �� P J f y� \ °wry = f a (�u y Z "� srn � i r'/cyynx':'ss> a'b�^� �'s m n I ' ?.� »cis s' :, a ..:t, wa w �i '•> p r �v '•g �"� M? K a. <^E � .y; . <'�.y . ^. e;, .e '~ a '.•r;. Y e L" ' °� �� %L:: .io •. wY laty \ ' »� \'�4< r c�i,a a• t" rw va � � > "�<:."?:9�e . , 'fl?? ,�y,y �c x J^'d `'f/y� >a> ,w,tt L oc �-r � f:?y F,i:, •>'• .a `Fi � \ .f Vf a .c'>GW ` »� c' �'..: 9? / ''"J < `7. �,"- Pro r� v< y, �;.. _ ;:a 4"'a✓' �o,, b 'oa c. - I r S"i � ,� .fi; .� J a. • : ar r . •;, �Q,s ..x cy w.. �_,,, v ,� ,� �• ,tz w :/, w ry Py � a,.2 .00R .�'' �o.� / rvi I'L• na P''4a,: -N./ '� � �>~ ' ,� !�% ' xy w'^ P ` ^ A � :3«v 8' y;: ? �: ,.2?: : r,,•.c ' S,, �.>e ; y:'So.''�t Pg t8: ' • aa. «,`: sp; �, ,�s✓-•,>3e�ya� r%:'b�q s a „xefw .Yf%<, S.-.�... 4;;<a�y, .s>^ y,. >Z Z,, ;yo ✓' , r,^i /, <vi?..,y ;�jF�; ?s;:, t�" >' ,. �` E �'' +2J<, x . r b J '.a o , �.. '< 1/ %� 1:: nf>tf^.ci'c. .. .:s<2� >sta�LO' ,., : xw ':bs�i�`•gex b:. e.,�.. �A... . ,r. Ex`. `+.....: ... ..-.�,< :•�;"�;'<.e. yt,, 1.::':L "�... ... � . ,.b° ,,...,,. .�:e�/f::;. v.:x>R'.5m:. ^. .v`fl a`�... < ,. is '.:i=�•�I' KV... �._.,�,:.r. ,-..,;/c•••, �P,:: 2 f �yS wz ?> K i-., or r. `k b: .:.y� ;'Yf<r ,eo ,Fy ,<�<. ,>y-.�„>.. ,w.xf:. _ ;� , a..y3`i'`+,H'l+.t»."" r'.�;,i' y� 'S� ;%3 7cf2P e✓,^ raw " > Y ,^� <� ;"'"�<•�.:::. r` ) R � �,�rir'Er ..s.� .<'� :, f, \c �: i.e o. o �i^;wr } s. <(,f•:.:o.iy r'Sa: e'< , :>""<�w.rry "'�rre.w.yfiy � > �; .. YP. � �� •.�yr '� <a �y'.�. ,v,.�b'° �_'V �, ,<��.:> < ' y! i2 � „Q RY x �`S�'tio \ `s$'\""7r' G`,i�' r "v ' y ,`. �' off'• , •ar::: �: FaJ"ELw!!!�►'. ,w.<.r {{2yrrL-;:<`„',« y ww�"eM",>; •:... icV t:: y < ...' «ywiov.>•:wi A? <C, �� ''` .6��'�'' !K ;�. ?�7ie'�c r ;S' /?� S o/ r fir. = AL �, >ki r yyu f roo.FPt 'iy \`9a w .r�k.> ��o �cb .6J ::� r>G,: : > �!Mr -YiG3 2 is ^'R' a �,.< `w'• � R`'c S .: D+" ..^s v !:�. f �o^.�F <3'% �;) ✓ 6j' a > ,;;)T�r,,o >:' r.>�"'r?t > ,� cut �'»�wr "�.w-»+�.««.> yc..,H:.: < o`+a''y.� \'.:. <- `PyR: �^ �yo. :c e, �' E d• , 4f 'J" he.w • , J S ��:' r.,: ^.d: 32r y%`.. /z, >nt PfgL�K• ^f�.. •' , ,SZ> s y.n., 'Aff"r,vcwxy «, .:.. �•.. ::. �y ia' >: ,,; .: o o>tiv^• Ja r} A' ._ ycaZ Q \., y 'y,c»ii^« X '6tt^iG).2...«+: � f` 'BrB .. S :'ro Jx � •� g d ,.>,.: / •. ,� �s��.. der X i,+yTa ,^ea.3r »•'_" e§'x ::. i � :y J /Q, r ^� tao ^r lf1 > ct� ;, .�., \ .. a ��' k"v tr 'Ge. b^a Q1 'h �'r s _ - 0 9 e•i' `�'t \` <' < 2'aYo y °°' ✓<,f ' ', a / aK X S y, -' jfs:°C c ." x � �. y, ti, G; ,^ ;2. d�:< •w' �tf yY@ ♦ •� (D �<f. < v .•ri t x Yi�>.a� � p,:, 00 x 2,.:>»%eos.< YS"F< <. Yo •S .n.awb. ¢o`.•+ fi;go. � �A•/ '�'�• 'aa:29'rs'2 i1t�e ;.. � F. ',g` J w � Y. _ w Vim. �a z k%w it' \ ,•^><a a L a r ,+ ? t f. v;;• { :a„ c'`x ,�. / r ' .. ji-�J"y 2a•' � X\ ..;?>.'. C Zaa ;� ,, ,r?c;' a«a) <i S• > \ eq - p�2, ,z \ b `r' F„L, "�. \ \: ' "' Wo,;.<!�Og •w yA �' 8y bS. rO.. .. r �, � ?� ',., ��,. N .. `Fv<' > ays 8fd3 two w,n• ?<,;,�• f}y°�c'?�'r t .>i y. ��`'$�'. eq..V .moo.-«.-.."-S ,.,.,.> �: yo' \ oil ds<y, ,w�J '°•?y \ o°. -`,may' . X 3F,_.- 2 r'�� y. '•e.:,. ' X 'i.� f S;, 'Y: � `•g, �v <3?. � X4' y L 2 •y A for /�\ 0° :> »yr aar a Y a .--��; ^off ^ �F�� `>) i A !✓" 6r "i «w. ','1 ' c •�'c;-Y be',!'� Ly.. C.<.f t K:. >f >7>J?*`^ A >,y�' f Sxrf`.• c k n, xt< y. r��Cra! " <t,�s, `" :�,`a. � %;•. b...!+..wnr+w.�M. ow... w:ey :: ... .� .Y <� •.< >dtv s:};, ex•. <'4 �xy<.. °Fe��. ',,,t �y Lam/M � 3Y: W f Ya`1' / . a.' - b LS ? o t.:c t s::w? �<a8 > `" �i?'A Q e>� °' =d,••V• ',a ; ' rb yJv :wA;.: ..: bY"' n rn . . o •%� 61< e 4. ; r/ y:�a' ?�<'t% ay<; yv . -'> i'> "b `>�.,k:6,3i?.st' : ` "«, a>• :;;,, ' F `" "t? 'd+°r''' d"'^ Jj r9 ,E�,f: �r t,' b, z �s. c , '. fy> y t t, v',a •.,_>: Lx•• ice.: ::i: ••... to '9Ri ^c':".bA✓' �' i ?\ 2 ,'. iE': b?XCB ?. '- t VOic:. C F > >,.'. '.. ,;Svc.'. '� r 3 % � cb,• Jr^rr , S?ck :c a'S4 ` v e. `tcz�% '• ,� t, a:, % .. r ° '. _ >G>". ° w>S r C"> 'S•,Y' < �„<. r °./ 4• $'e> ails (.'�bt .f" v : ^^�if,f yy<,.,�. �Y..'°°wt°lGS4:s. 4j:' Kc. ;.:. a..e.::' � ^"° c.,�:.`6 >`�� "6 f e ).y t, <:il�,z ),yJ b °� ,� KS� :yy�?t?• : \2�r os y'<\'<` r .� '.d Asv�L � ':.+�+..r-�..,�� `°)�°,.c >:i �'O�a f r 'k') off <y, a$ 2 y wy L� ao:`+\ ,2 i J S�'W... •�_� 4,�'R� f �y '>./ �: !a ,'r:" '"g i etis^'' k :bc E >• � k;R "f :>;;f � .,y.. .� � ', I y�a�syY �:. "`') .<m,3kcrt.,cw :o k•2R. > yPt. ; Y'K e e .•has ,,� ,•, a 1 '! ,:� 8 ✓ >> rxra �..�- .!�, j.�"i>sx/< S 4 r .aJe < �. t `: �<� '- 4<., _ 'SIB %>o\)�.: /". '�sfYn <>9/ 7. : f �f .:T , wy „I„;• r •�•-:Y/ "` < "";; ! ze « '� i5 '' " t� , '. •cam P sz' yri .. „' 2 ,» �.� �'^ r ><�, : • '1q£.of'a' :y'., ro*fT<. ,� F2•�,: „<?. '.;c � : ti', r•.;: .: `;'\ is �`- .r ",:i',a o q` M ...« Rt. .r�� . "`�v6$ G'2 {` >:22 •^34 2 `i:'•: 'et �y. W�> k;�{a:�s. ,^ q., �°� � . ♦.. � `� t „ r r E` `' '. ia. '?.. °' :• if��: a'ir.:! gY�9'^'..6R� y' :; "•a«> n ?eilYa' <"�' o. `; y o.¢t"�"'^' .�f•.. _�, .A�a y �ea �J/ r ,a✓e <°» ,d�� •i. s; ,� J^8 > rcfr <�, Wd: ;%�'4 ;�Geo3 � tf .<:sq:.> , c� :• �c a •'y<s, ", ,>''�„•em v Yr/,t y'�° ' s:�F" ?fy /W%M'' �`> .,b•. ^ �y:: ApkL:6; ,t e �w. '.�6< • ", r fFc g %y : 'ei?' >� �' . y`, � , • ��j,�` ';; c6 ' • K�:y" �.c .4iA <r� .., :'"� >� ' '6J 3::�. /G,p.r„ �::, '> r';;''e: /f ,,as'nf.? �� RYP; ;z" s).. 19�,>,.;.,?Y?: '�F,?,aip. :<,.✓ wi tr . w "vSy.a %./ x. a �P?Gx Yctk' , ,, , i ?nP.>ia`' ::h v: >k!, ,Y^ A y-r. 'o w,ofiat .i>.; •h�:. • <+ � tyyi,) >.> SA>,f<�f S „ �fi^ � ''�.. ' .�.. . � ,9 `�, :. fl • f ': .,.. f .,f:-, q >n ✓.•.ryf: a� �yM .• wY''. ,>4 .(�y.'•• r. ,yA. .y Y Q�. ",�f»,a,„„ ..y. ' f6<^"' ' ,y.,y� ,f, L: '>L 'y, , V ^ •t, x- .Ja' .+. .e `F n�C' ''\Y' W> , vl . �y"%'�y�'t°- � ,: Sr e r • :Y, 'f<•,::; .��, .y, �. dr esyL,., rrk," ^ � :�! .;,/>/J� ', �:c � J `�ec.y ).. d`f��:. �I.ok .s'. �.°4 >' +E^ .w. %• � %Sb. P l°' tY'; "C?.J a;@.: . � � \ d•"J ' n, 9' `?o:.. :Lcg,, 0>> aN a,�. r�'q• � q ,» f q v. � o•..., ,m. r � Y. rJF< ,..�,;:A;Si�� /� ..w.,;6� cJa >Yd:.'P' : f ,. ;;., .. A% �yi5%x>�'4 i� ' � lit c : i ^. Yc>.4/ > Y.ti>�odzc> .. � ,o •r'.« i e'"�r`F° `�Fo�,�. �>{ f¢ » A V 0'1 � -` ,.a< F. a :: J ' •_7'^a uoi : ^ C f� L < q� +'Y, a (! ) ..> V iw /,./��''e% ><9' Wi 'ryGP '. i��' R �y < ab/ . 4� """) •f•,gr„'G° : i' f� Sj, >, Q. �t� w, •:- y 4 •?3� � (,'��.,F'Y•<,.;r:...^ > c ` f � o• a x rCr w: w , �) K: J j �� ':S<Y '^, t�w�,..R wC'f „,.•r /Y>!'.:. �' ��f ,1 � �' a+. «. R e.� t�� d �"S ♦)If`� !,[ ^ °b .sf'.',. .<�< e2YV ��` � • '� r w <, b � `f$ � S w...i> 1. °� ,,°.> � sb � e fy��jl'� y � de'f •• wx ': SOJ or \ w yy �. - x.., `p,y�.�// ). yyyk •JH\., f i xw,3✓,/�vi fn f> ''YgL>•+a" 1 `..�,.". �• F�� r Z•��'°Sh' SYro:.� .S<;,,'� � v •�• .'�.f .tf" 'a` \ r3Y�" i N +a,d� '` � »iy, P . "�0 ".< f '� . { "W •y� � ,is,•. �'� •°`�R' � Z 'YM .adi- .fy.. w `•>' '�'loe:a wo' <.q' ft' � r `:.� ...,. �y Y .j?'n�wf;",% ...r � a ; � � A'. ,�?y�:.. :. 2.>'td�.?� : 4 RC;'' : t�>^ � • vPr Sii: \�•iY Y�r: i'. a^ � f,F A� ,.;Y �• ,�'•''f=i r ',2„H;°'?a p; . A _ if : %': w >t :an :ys'.. ' r `;,�,° �r.> 'i r \ ..d,�",� • ' 0.. '.;� u0o'• i»!�!^' Q' - 3. � F �':. r y a : ; A,rj fz$c. 6 `j�i',i'' 3. ja �� ' a• °r a . ' ^ � X�:, d?:z?if.•, ,!^ts ai%q<y, ;.y, .>::: y'«' ;.!/<. � W i�� µ�..�.� �� Y,l >�•.%- s �.> dJ y�)1111f�f =�. � o'� y, >'"y S6 SJt �" �`� .,h �'ic >�• ,. 9 � , :z. : fdog'y, Jr: •� r, ��ll<<s4�� r r i,'> s ;i y ,rr , fS` .R'wzg»zao',sk L>3!>r' ,•y a ',�y:.i e. v.°�gbyo>` wr YrL' Y N >r, .r- , Y�,,V y.+. v �"'.'.�, ... .i5e•K',!•' / 6• c �! ,y� ��w :y A'• <>> H Pi` wK ..e' ' Y°.° a; //� :; �.. ;•, �.r'. v„ P.Ns '�. '` 0t;?Y °\'s - a L, : v. ^,.,�•��Si?i4o-. "`� � 704?.� ��:> r KrY >�t ,�q>'� � �S':5?M `•, RS�e �'>'�`3 c?,.. >s"'a f'�bA�M'•%'%ei"�"<4•.f"�AJ"�...�w""° N, o r. •'S' 9 «�f�?: n `•' .c '<:i` �.c>� �:Zf�", E �y" \ � `.f'? r;;.`Y,":;•.e,�,..;;,�� • < :ro ;Jzb/�'• .. k4. ;k 6� c° " Vim= ? y : r r, K ibJ,: • t ofY l ? ;P2a, i ��..� Ye6 \ •, A. ' � p� f°' ' a A.. t, � •R.v/C:. 0.,:c,., y � w. a `';c �c, ''a ' �e�' '. ,v>�s E`<` Ni'' �:. w. I .;� kf!<� ,c z ••. •! `. "'...,oco• y' rd,.. � � ,'• 'v �•Sy'.f>i9y� a �.... gY '•; a� � � />' \ •8>' :. �� a: cia•'�� , ' :», �`�"^>' '•�^^'�""eY�`� j° 0i�.e> , y c i 'fia` � ...,y,�2 �yc„^,,. Av '!T�,• '°> '•^ I , •••R��> 4z >: ^aF� .: '�%FW' .:. �� ., : :?;t: �° « ,\•v�, °V'" v. cerJ>,.. �. 'Z 17 �,. «^ r �, '' � ,x r o>^ ox " rR �• v.i A`V ,, �..> •• w�« a r yR . •:�;: � �'. �,�, <ox ` a`r.: �" f^,jt1 �✓, r ,y-�•w....::;,,t,•r'�.'c�a �" xy ,si�''au'� �a ' •�<�t,� ��,r`:f .2.•..t:.`v.° �� ' q>a . X ,..t• ..a w0 rid . /: `r. r,�`a�F A.K °° K �? • ^r c w w . a>. , ,, )'6s `"'•,::ad""; " • 'w �'^� A or+s' • A4 ^'; i. �i I •A 3f. _ �. b>.: �• _....�� 2'L i.--a__ - ,>.iNw..� ,�FR�• '��" � ..,. :y �r x: Sit 68a ' a, 15714 15631 ^ 15709 15707 118 ? 15722 137Ie Lij 6808 S �/ t-8 - 1-136J > 1-119 15M 157ZB 15724 15729 1J7PJ � h � �� I5720 -tit 1-t44 - 43 I5730 l5732 1 �° 1 1-166 158�ri-i 1-142 1-140 1- 1-150 7¢00 5810 PIEZtI 1-141 1-2 lS808 15814 TUBE 41 15Bl4 IJ800 1590 73P4 - 49 > IS809 } No�TH 3 138P4 t-►28 = 15810 15818 1-7 e � Zoo • 158l2 1-t48 0 � p f -]27 15824 1382J ~ il- I5BP6 i 13828 I-� 1-147 15827 15908 t=146 1-3t 15904 _3 _ 1-29 } J t. l5911 JS907 1J902 1-4 _ J5910 Q 5906 15910 1-27 ^ 1-174 Zt/2 15902 1-1 159 0P lJ912 1 26 -76 tU (� 5917 t-19 1i4 _ 159I5 15920 PIE ZU �" 16000 1_ 1-79 f-781-77 Zio t- 1� rr t 15926 691I 1-I17 b909 13920 1_3 < -•ate , 1-74 160TH T SW l- L 1-24-231-22 1-211-23 1 2 i-81 16121 1-116 - 16012 1-73 15931 /6123 Moe 6c720 6910 t- 600 1600 ` 1-as t- 6970 1-84 16me t-tt2 160P4 1600 12 N f �,�Z 1-87 1-36 6916 6826 1601 603I 00 16119 16115 16020 1-10 6010 i-l7 6960 Q ! l l 1-171 t-71 6920 ls03B 3 1-u Q u I61 0 16109 ,9 1-t34 L-i33 , 1-111 1611! 16! GRMD v E �v- 10,6 1-170 1-75 J6209 69J8 6809 6903 161 Q4.1 B ALL INT OR SYSTEM t-169 CM 1' S T P. l610 1610 t-12 v' 1-456 16100 -6 16215 1-133 6604 t-9a t-�, t-136 t-42 4 611 l6113 I 8 -t37 t3 LLJ Q l6131 6 6I21 16122 6217 16116 h 1-43 1-173 ND WATER 1 38 Q f-89 INTERCEPTER 1-44 SYSTEM 16209 16P16 0� A 1-90 t-88 Moe\ / J6e11 1-16t _101 OPEN SPAC£ 1-13 v P 20 T BE 16209 Q 6PI4 t-� 1-SS 692J 1-4t d • ,Q 16220 1'40 ti 2e0 16219 6923 6801 t-14 -S7 -52 1-100 t-102 l6310 1_gg 16P38 /� 1-33 16c'P3 622d 16278 '0 1 6805 l63P0 1-38 1-163 � 16225 1 2! 16991 1-103 I62 3P 16232 ! 6908 1-15 l6IU Z 1_l� /6317 1-90 6919 1-104 16330 �� t- w 6915 6802 1-13a` 1 N t 64 163I8 /6315 16320 l -177 ,6909 16404 16319 1- 38 1 6901 1-93 1_165 163 1-16 PI ZO TUBE 7 0 �t-p�.i �v(�LI _1B0 16429 .� ", ^ 1109 163?3 163c'2 - 16-70 p c• 1-1" 1-% 1 t-6 4 '� 1-54 1-30 1-47 1-'14 1--93 6904 l-l7! z 0 H U V JN. 1�- gf� OCD DAVID EVA.NS AND ASSOCIATES, BY j�j CLIENT _jQq_}`!--��QSHEET _QIOF —_ SHEETS JOB DESCRIPTION l _.� . -�—�— --(—D---- — DATE I i c� 4-2 7--t Ql-J ! j F �L'�-:--TI+-�c� Gop �-r �a►�S G�J _ Tc�T-4 t s 3. (1... (11 ACITZ �s -3 1 Till O. �a•5s12, ,.�4��01. 1 I , _ 1 X �O JN. -PAv 000� DAVIDVI EVANS ANASSOCIATES, By J \ A CLIENT -j Gl {- J ��-i`� �j�l� 1 - _- _-- - SHEET 2 OF -- - SHEETS P JOB DESCRIPTION DATE I ' j 1 l 8Co; ,Ut-� �r ' b7 ---- -�.2�'L. 1 I - i GN_ -_ X 1 �T 1 r� U l Z " l N T►G - - -- -- - � I call 1 �.=:0-74 5 Q Loci = I,OCo DAVI D EVANS''jAND ASSOCIATES, ' CLIENT J [[�_jJ T i JOB DESCRIPTION JN. T� OC�O I BY�, ) jj��I SHEET (�3 OF SHEETS DATE - I /2�-/5 - Ll3+ v,-7 4 = 1,'l G� I �xts�►�v, �� (��- �� Q �� I Pow pr--o, t r•.�A-G �S ,�� i JN.o DAVID EVANS AND ASSOCIATES, By ' CLIENT"O _- Q j�L SHEET -OF -SHEETS JOB DESCRIPTION( ,IGQ I-� C1 DATE _ I_� �✓/�,� _ C- I 7¢ o JZ- 1 `L�(�Pl Cvo s� � � N �0�� - �, -►-- -ram . - �, Z-r �,.. I I I �� T I ►�- � 15�.-0 � - -- _ -�-Q old -�� ---o � --- �-------- SPECIFY STORM OPTION: S.C.S. TYPE-lA RAINFALL DISTRIBUTION NTER: FREQ(YEAR), DURATION(HOUR), PRECIP(INCHES) 5,24,2.5 ******************** S.C.S. TYPE-lA DISTRIBUTION ******************** ********* 25-YEAR 24-HOUR STORM **** 2.50" TOTAL PRECIP. ********* ---------------------------------------------------------------------- NTER: A(PERV), CN(PERV), A(IMPERV), CN(IMPERV), TC FOR BASIN NO. 1 86,86,.44,98,6.3 DATA PRINT-OUT: IAREA(ACRES) 1 1.3 PEAK-Q(CFS) .53 ENTER PERVIOUS A CN .9 86.0 T-PEAK(HRS) 7.83 IMPERVIOUS A CN .4 98.0 VOL (CU-FT) 7508 TC (MINUTES) 6.3 [d:][path]filename[.ext] FOR STORAGE OF COMPUTED HYDROGRAPH: SPECIFY STORM OPTION: ,1 S.C.S. TYPE-lA RAINFALL DISTRIBUTION ENTER: FREQ(YEAR), DURATION(HOUR), PRECIP(INCHES) 1100,24,3.0 ------------ ---------------------------------------------------------- ******************** S.C.S. TYPE-lA DISTRIBUTION ******************** ********* 100-YEAR 24-HOUR STORM **** 3.00" TOTAL PRECIP. ********* ---------------------------------------------------------------------- ,ENTER: A(PERV), CN(PERV), A(IMPERV), CN(IMPERV), TC FOR BASIN NO. 1 .86,86,.44,98,6.3 'DATA PRINT-OUT: AREA(ACRES) ' 1.3 PEAK-Q(CFS) .68 ENTER PERVIOUS A CN .9 86.0 T-PEAK(HRS) 7.83 IMPERVIOUS A CN .4 98.0 VOL (CU-FT) 9610 TC (MINUTES) 6.3' [d:][path]filename[.ext] FOR STORAGE OF COMPUTED HYDROGRAPH: SPECIFY STORM OPTION: ISL.C.S. TYPE-lA RAINFALL DISTRIBUTION ,ENTER: FREQ(YEAR), DURATION(HOUR), PRECIP(INCHES) 25,24,2.5 ---------------------------------------------------------------------- ******************** S.C.S. TYPE-lA DISTRIBUTION ******************** ********* 25-YEAR 24-HOUR STORM **** 2.50" TOTAL PRECIP. ********* ---------------------------------------------------------------------- ENTER: A(PERV), CN(PERV), A(IMPERV), CN(IMPERV), TC FOR BASIN NO. 1 2.73,79.2,.44,98,6.3 DATA PRINT-OUT: ' AREA(ACRES) 3.2 PEAK-Q(CFS) IENTER 74 PERVIOUS A CN 2.7 79.2 T- PEAK (HRS ) 7.83 IMPERVIOUS A CN .4 98.0 VOL (CU-FT) 12025 TC(MINUTES) 6.3 [d : ] [path] f ilename [ . ext ] FOR STORAGE OF COMPUTED HYDROGRAPH : SPECIFY STORM OPTION: 11 S.C.S. TYPE-lA RAINFALL DISTRIBUTION ENTER: FREQ(YEAR), DURATION(HOUR), PRECIP(INCHES) 100,24,3 ---------------------------------------------------------------------- ******************** S.C.S. TYPE-lA DISTRIBUTION ******************** ********* 100-YEAR 24-HOUR STORM ****, 3.00" TOTAL PRECIP. ********* ---------------------------------------------------------------------- ENTER: A(PERV), CN(PERV), A(IMPERV), CN(IMPERV), TC FOR BASIN NO. 1 2.73,79.2,.44,98,6.3 ' DATA PRINT-OUT: AREA(ACRES) ' 3.2 PERVIOUS A CN 2.7 79.2 IMPERVIOUS A CN .4 98.0 TC(MINUTES) 6.3 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) ' 1.06 7.83 16318 ENTER [d : ] [path] f i lename [ . ext ] FOR STORAGE OF COMPUTED HYDROGRAPH : SPECIFY STORM OPTION: '1 S.C.S. TYPE-lA RAINFALL DISTRIBUTION ,ENTER: FREQ(YEAR), DURATION(HOUR), PRECIP(INCHES) 25,24,2.5 ---------------------------------------------------------------------- ******************** S.C.S. TYPE-lA DISTRIBUTION ******************** ********* 25-YEAR 24-HOUR STORM **** 2.50" TOTAL PRECIP. ********* ---------------------------------------------------------------------- 'ENTER: A(PERV), CN(PERV), A(IMPERV), CN(IMPERV), TC FOR BASIN NO. 1 74,77.9,13.6,98,8.7 DATA PRINT-OUT: ' AREA(ACRES) ' 87.6 PEAK-Q(CFS) ' 18.70 ENTER PERVIOUS A CN 74.0 77.9 T-PEAK(HRS) 7.83 IMPERVIOUS A CN 13.6 98.0 VOL (CU-FT) 322312 TC (MINUTES) 8.7 [d : ] [path] f ilename [ . ext] FOR STORAGE OF COMPUTED HYDROGRAPH : STORM OPTION: ,SPECIFY 1 S.C.S. TYPE-lA RAINFALL DISTRIBUTION 'ENTER: FREQ(YEAR), DURATION(HOUR), PRECIP(INCHES) 100,24,3 ---------------------------------------------------------------------- ******************** S.C.S. TYPE-lA DISTRIBUTION ******************** 100-YEAR 24-HOUR STORM **** 3.00" TOTAL PRECIP. ********* ---------------------------------------------------------------------- ENTER: A(PERV), CN(PERV), A(IMPERV), CN(IMPERV), TC FOR BASIN NO. 1 74,77.9,13.6,98,8.4 ' DATA PRINT-OUT: AREA(ACRES) PERVIOUS IMPERVIOUS TC(MINUTES) ' A CN A CN 87.6 74.0 77.9 13.6 98.0 8.4 PEAK-Q(CFS) T-PEAK(HRS) VOL(CU-FT) ' 27.17 7.83 438160 ENTER [d:][path]filename[.ext] FOR STORAGE OF COMPUTED HYDROGRAPH: L j DE 0i-,: i.N*i L- f,`v i i- L v-,-R. CITY OF t-'D f-A, G N D S Group Northwest, Inc. Gootechnical Engineers, Geologists & Environmental Scientists GEOTECHNICAL ENGINEERING STUDY SEQUOIA RIDGE SHORT SUBDIVISION EDMONDS, WASHINGTON G-1061-1 Prepared for Mr. John Thoresen Sequoia Ridge Partners 15621 - 48`h Place West Edmonds, Washington 98026 February 29, 2000 GEO GROUP. NORTHWEST, INC. 13240 NE 20' Street, Suite 12 Bellevue, Washington 98005 Phone: (425) 649-8757 1 Geotechnical Engineers, Geologists Group Northwest, Inc. &Environmental Scientists February 29, 2000 G-1061-1 Mr. John Thoresen I Sequoia Ridge Partners 15621 - 48' Place West Edmonds, Washington 98026 Subject: Geotechnical Engineering Study Sequoia Ridge Short Subdivision j Edmonds, Washington Dear Mr. Thoresen: Geo Group Northwest, Inc., is pleased to present our Geotechnical Engineering Study report for the Sequoia Ridge Short Subdivision in Edmonds, Washington. This report was prepared in accordance with our proposal dated September 22, 1999, and the City of Edmonds guidelines for geotechnical reports. It is the opinion of Geo Group Northwest, Inc., that the site is geotechnically suitable for the proposed development, provided the recommendations in our report are followed. Although i there is some inherent risk in any proposed development located in or near to areas of steep slopes or geological hazards, it is our opinion that the proposed development will not increase the potential for soil movement at the site. Please refer our report for a detailed discussion of our conclusions and recommendations. We appreciate this opportunity to provide you with geotechnical engineering services for this project. Please feel free to call us if you have any questions. i 13240 NE 20th Street, Suite 12 • Bellevue, Washington 99005 Phone 425/649-8757 • FAX 425/649-8758 February 29, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page ii Sincerely, Geo Group Northwest, Inc. William Chang, P.E. Principal �q 2014 � �GtSry'E+�� fJiVAL Lefts 2/194200 2- Geo Group Northwest, Inc. TABLE OF CONTENTS G-1061-1 Page 1 INTRODUCTION......................................................I 1.1 Project Description ................................................ 1 1.2 Scope of Work ................................................... 1 2 SITE CONDITIONS....................................................2 2.1 Site Description................................................... 2 2.2 Geologic Conditions ............................................... 3 2.2.1 Regional Geology ........................................... 3 2.2.2 Soil Survey................................................5 2.2.3 Site Geology ............................................... 5 2.2.4 Groundwater...............................................6 2.3 Wetlands........................................................7 2.4 Geologic Hazards.................................................8 2.4.1 Erosion Hazard ............................................. 8 2.4.2 Steep Slope and Landslide Hazards ............................. 9 2.4.3 Seismic Hazard ............................................ 10 2.5 Geologic Hazard Area Buffers and Setbacks ........................... 11 3 CONCLUSIONS AND RECOMMENDATIONS ............................ 12 3.1 General........................................................12 3.2 Site Stability Evaluation ........................................... 13 3.3 Site Preparation and Earthwork ..................................... 14 3.3.1 Temporary Slopes and Excavations ............................ 15 3.3.2 Subgrade Stabilization ...................................... 15 3.3.3 Structural Fill ............................................. 17 3.3.4 Pipe Bedding..............................................18 3.3.5 Trench Backfill............................................ 19 3.4 Erosion and Sedimentation Control .................................. 20 3.4.1 General Development Standards ............................... 20 3.4.2 Erosion and Sedimentation Control Plan ........................ 21 3.5 Foundations ...................................................22 3.5.1 Deep Foundation Systems .................................... 22 3.5.2 Shallow Foundation Systems ................................. 23 3.6 Building Floors .................................................. 25 3.7 Permanent Basement and Conventional Retaining Walls .................. 25 3.8 Modular Block Walls ............................................. 27 3.9 Rockeries.......................................................28 3.10 Site Drainage ...................................................30 3.10.1 Surface Drainage ........................................... 30 3.10.2 Footing and Wall Drains ..................................... 30 3.11 Pavements......................................................31 3.11.1 Driveway Support .......................................... 31 3.11.2 Driveway Stream Crossing ................................... 32 3.12 Post -Construction Soil Stabilization and Re -vegetation ................... 33 4 CONSTRUCTION MONITORING AND ADDITIONAL SERVICES .......... 33 5 LIMITATIONS.......................................................34 REFERENCES ILLUSTRATIONS Plate 1 Plate 2 Plate 3 Plate 3A Plate 4 Plate 5 Plate 6 Plate 6A Plate 7 Plate 8 Plate 9 APPENDIX A Site Vicinity Map Site Plan Development Plan Vicinity Drainage Map Geologic Map Subsurface Profile A -A' Subsurface Profile B-B' Subsurface Profile C-C' Landslide Hazard Map Basement Wall Backfill Details Typical Footing Drain Soil Boring Logs (Geo Group Northwest, 1999) Hand Auger Boring Logs (Nelson-Couvrette & Associates, 1995) APPENDIX B Rockery Construction Guidelines 1 GEOTECHNICAL ENGINEERING STUDY SEQUOIA RIDGE SHORT SUBDIVISION i EDMONDS, WASHINGTON � G-1061-1 1 INTRODUCTION r- 1.1 Project Background Sequoia Ridge Partners proposes to subdivide and develop the subject site located in the Meadowdale neighborhood of Edmonds, Washington, into four single family residential lots. The proposed short subdivision would be named Sequoia Ridge. The four proposed residences would be built on the western part of the site, near the top of a steep west -facing slope that offers views of Puget Sound and the Olympic Mountains. The site location is illustrated in Plate 1 - Vicinity Map. The proposed lots, labeled Lots 1 through 4, are indicated on Plate 2 - Site Plan. Access to Lots 1 through 3 would via a proposed driveway that would extend from the northern terminus of 72" Avenue West. The driveway for the proposed residence in the northwest part of the site (Lot 4) would be via a driveway from North Meadowdale Road. The north driveway would cross a small stream on the north side of the site. 1.2 Scope of Work I ' The scope of work performed for this study was consistent with generally accepted geotechnical engineering practices and with that presented in our proposal dated September 22, 1999. The scope of work included the following tasks: • Use the results from the - . i U eon site subsurface investigation work previously performed during the Limited Scope Environmental Impact Study completed by Geo Group Northwest, Inc., in 1999 (Geo Group Northwest, 1999), and the results from a preliminary geotechnical investigation of the site reported by Nelson-Couvrette & Associates (NCA) in 1995 (NCA, 1995), to assess soil and groundwater conditions at the site. Perform engineering analysis for foundation support, grading considerations, pavement section design, utility trench backfilling, and earthwork criteria for on -site soils and imported soils. Geo Group Northwest, Inc. 1 February 25, 2000 G-1061-1 r Mr. John Thoresen - Sequoia Ridge Partners Page 2 • Prepare a report that summarizes our activities, findings, and conclusions regarding the proposed development of the site. The report will contain recommendations for the - geotechnical aspects of the proposed development at the site, including; - Pile -supported foundations and floor slab support, - Subgrade preparation, - Concrete and asphalt pavement section design, - Soil parameters for rockery and retaining walls, - Rockery construction guidelines, - Bedding and backfill requirements for utility trenches, - General grading and earthwork criteria, Site drainage, - Geotechnical recommendations for the driveway stream crossing, and - Suitability of on -site soils as structural fill. Detailed construction plans for each of the four proposed residences were not available at the time this study was conducted. Geo Group Northwest did receive and review construction plans for Lot 2 at the site, but not for Lots 1, 3, and 4. A geotechnical review of the construction plans for the other three lots can be performed when the plans are available. 2 SITE CONDITIONS -� 2.1 Site Description The site is an 3.66-acre parcel of undeveloped land located in the Meadowdale neighborhood of r Edmonds, Washington. The site vicinity is illustrated on Plate 1 - Vicinity Map. The site is bordered by North Meadowdale Road on the north, by undeveloped land on the east, by residential property on the south, and by a residential development at the bottom of the slope to the west. A small stream (Meadowdale Creek) runs across the north part of the site, adjacent to North Meadowdale Road. Utility improvements in the site vicinity include a municipal sanitary sewer system and a system of interceptors drains and trenches that capture drainage and convey it the local storm drain system. Site conditions and proposed storm drain and sanitary sewer �� Geo Group Northwest, Inc. i r February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 3 systems are illustrated on Plate 2 - Site Plan, and the currently proposed residence locations are shown on Plate 3 - Development Plan. The drainage system installed by the City of Edmonds in the Meadowdale area to mitigate potential landslide activity in the vicinity of the site is illustrated in Plate 3A - Vicinity Drainage Map. The site is characterized by moderate to steep slope topography. A narrow ridge with moderate to steeply sloping sides runs roughly north -south along the western part of the property, and broadens eastward along the south margin of the property. The slope on the western side of the ridge consists of a steep slope (portions of which consist of near -vertical bluffs) and is thickly vegetated. The upper part of this slope on site has an overall inclination of about 45 to 60 degrees (equivalent to 100 to 173 percent), but tends to flatten out somewhat further downslope. !� The east side of the ridge is moderately steep in its upper portion, having slopes of about 24 to 30 degrees (45 to 58 percent) and also becomes flatter to about 16 degrees (30 percent) downslope. The height of the steep west -facing slope ranges from about 40 feet at the north end of the site on Lot 4, to about 110 feet below Lot 3, to approximately 130 feet at the south end of the site on Lot 2, based on topographic data for the site (shown on Plate 2), and available topographic data for the adjacent property to the west presented in a geotechnical engineering report prepared in 1989 by Terra Associates, Inc. (Terra, 1989). As noted above, the slope varies in steepness, with the uppermost portions typically being steepest (up to vertical in places). Below the steeper, upper part of the slope, groundwater seepage and silty soils are present. Most of the slope is thickly i vegetated with shrubs, vines, grasses, and deciduous trees. 2.2 Geologic Conditions i2.2.1 Regional Geology The proposed project site is located in the Puget Lowland physiographic province, a north -south trending topographic and structural basin. Geologic processes including tectonic uplift and subsidence, glaciation, and erosion by streams have acted to shape the physiography of the area. The site vicinity is underlain with Quaternary -age sediments associated with past glaciation of the Puget Sound region,, as illustrated on Plate 4 - Geologic Map. Limited areas are underlain with younger alluvium deposited by streams, and some of the sloped areas may have a surficial Geo Group Northwest, Inc. February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 4 layer of colluvium. The majority of the glacial sediments are from the Vashon Stade of the Fraser Glaciation, which occurred approximately 13,000 to 11,000 years ago. Some pre-Vashon age, non -glacial to transitional environment sediments also are found below the Vashon sediments in the proposed project area (Minard, 1983). The Vashon-age glacial sediments present in the site vicinity consists of (in downward succession) compact till (composed of unsorted mixtures of silt, sand, and gravel); moderately to very dense, fine-grained advance outwash sand and silty sand; and'dense silt with lenses of silty sand. At the site, the pre-Vashon age deposits consist of silts with some interbedded fine sand interpreted to be the Whidbey Formation. The geologic contact between the Whidbey Formation silts and the overlying outwash sand often is an area of groundwater springs and seeps. The site is located immediately east of the Meadowdale Landslide Complex, which was mapped and characterized by Roger Lowe and Associates (RLA, 1979) and GeoEngineers (GeoEngineers, 1985). The Meadowdale Landslide Complex is a large area of historical landsliding (slumps and debris flows) extending about 3,200 feet north -to -south and up to 650 feet. east -to -west. The steep west -facing slope on the site forms the eastern margin of the landslide complex, and is the head wall of the landslide zone. The initial movement of the landslide is believed to have occurred about 7,000 years ago. Active landsliding in the area has primarily occurred within a 400 feet wide zone immediately east of the Burlington Northern railroad tracks (the zone would be located about 100 to 200 feet west of the proposed project The most recent movements - - site). o ements m the landslide complex (m 1946 47, 1955 56, and 1970 71) have occurred in the middle and western portions of the complex, away from the site. The previous studies determined the primary cause of ground failure in the Meadowdale Landslide Complex has been a combination of shoreline processes at the bottom of the slide area and erosion caused by groundwater flowing from springs and seeps on slopes at the contact between the outwash sand unit and the underlying silt deposits. Erosion of the base of the affected area was the primary cause of the initial large-scale landsliding and of subsequent smaller slumps and movements in the middle to western parts of the slide complex. Sloughing and small slumps in the eastern portion of the complex (including the west side of the site) that occurred after the initial large-scale landslide event have been caused primarily by erosion by springs and seeps in the steep west -facing slope Geo Group Northwest, Inc. 1 ill I February 25 2000 �G-1061-1 ,i Mr. John Thoresen - Sequoia Ridge Partners Page 5 2.2.2 Soil Survey Surficial soils at the proposed project site consist of Alderwood gravelly sand loam on 8 to 15 percent slopes and Alderwood-Everett gravelly sand loam on 25 to 70 percent slopes, according to the U.S. Department of Agriculture Soil Conservation Service (SCS) soil survey for Snohomish County (SCS, 1983). Alderwood-type soils are typically moderately well drained, have a depth to the hardpan (glacial till substratum) of about 35 inches, and are developed on till plains. Alderwood-Everett soils are typically moderately well to excessively drained, have a depth of up to about 60 inches over hardpan and glacial outwash, and are found on nearly level to very steep slopes on till plains, terraces, and outwash plains. Permeability of the Alderwood P h' soils is relatively rapid above the hardpan and very slow through it, while permeability of the Everett soils is rapid. 2.2.3 Site Geology Based on the findings from site exploration performed by NCA in 1995 and by Geo Group Northwest in 1999, surficial soils on Lots 1 and 3 consist of glacial outwash sand to at least 30 feet bgs. We encountered a surficial veneer of gravelly, fine to medium grained sand in the soil boring drilled at the proposed building location on Lot 1. This surficial soil corresponds to the ' uppermost part of the outwash sand unit where it was directly overlain by glacial till. A cap of glacial till may have been cut from this part of the site when the residence immediately to the south was constructed. Surficial soils at the proposed building location on Lot 2 consisted of at least 12 feet of very dense glacial till soils composed of silty fine to medium grained sand with gravel. Shallow hand auger borings completed further east on Lot 2 encountered outwash sand and not glacial till soils. Based on this information, the extent of glacial till soils on the site is anticipated to be limited to the western part of Lot 2. Silt and silty sand deposits identified as transitional between the outwash sand and the pre- Vashon age Whidbey Formation deposits were found at the ground surface on Lot 4. Encountered soils consisted of a surficial layer of fine sand and silty sand (similar to glacial outwash sand) about 4 feet thick, underlain by interbedded silty sand and silt to 30 feet bgs. �' Geo Group Northwest, Inc. 1 February 25 2000 _ �� G 1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 6 A soil classification legend and logs for the soil borings drilled by Geo Group Northwest in May 1999 are provided in Appendix A. Soil logs from hand -auger borings performed by NCA in 1995 also are included in Appendix A. A south -to -north subsurface profile of Lots 1 through 3 on the site is presented in Plate 5 - Subsurface Profile A-A'.A west -to -east profile across Lot 2 is presented in Plate 6 - Subsurface Profile B-B'. A south to north subsurface profile of Lots 3 and 4 is presented in Plate 6A - Subsurface Profile C-C'. It should be understood that the proposed locations and configurations of the homes and driveways on Lots 1, 3, and 4 are schematic at this time. Final locations and elevations of these features will be determined at a later time. "! During our site investigation, we observed small slumps and areas of relatively recent sloughing on the steep slope in the west part of Lots 2 and 3. A silver -colored tarpaulin was observed to be covering one such area of sloughing along the steep slope near the boundary between Lots 2 and 3. We observed no evidence of significant soil movement on the north and east -facing slopes on site, and NCA reported that they did not observe any indications of deep-seated soil instability on the site, but did notice some evidence of surface soil creep. 2.2.4 Groundwater During our subsurface exploration of the site, we encountered groundwater at a depth of approximately 30 feet in the soil boring drilled on Lot 3. Groundwater was not encountered in the borings drilled on Lots 1 and 2, but is suspected to be present at a greater depth (the borings on Lots 1 and 2 were located at much higher elevations than the boring on Lot 3). A very thin zone of wet soil (about 1 foot thick) was noted in the surficial weathered soils on top of the very dense glacial till in the boring on Lot 2. These findings are consistent with the geologic literature for the area, which describe the presence of groundwater in the glacial advance outwash deposits on top of the underlying silt deposits. Groundwater was present within the silty sand lenses in the silt soils encountered in the soil boring drilled on Lot 4. These observations are consistent with similar findings reported in the literature. We observed that the steep west -facing slope on Lots 2 and 3 of the site has a distinct zone of seepage and springs located at the boundary between the overlying fine sand layer and underlying silt layer. This zone is located at elevations of approximately 220 to 230 feet. Water from these ' Geo Group Northwest, Inc. I • - - February 25, 2000 G 1061 1 Mr. John Thoresen - Sequoia Ridge Partners Page 7 springs flows downslope off site and infiltrates into the soils on the Lorian Woods property, or is diverted into catch basins connected to the local storm drain system. Seepage from the west= facing slope on Lot 4 was not observed during May or June 1999, but was observed further downslope on the adjacent residential development property. The elevation of the stream as it passes through the site, according to the topographic survey data on the site plan, ranges from approximately 215 or 218 feet at the northeast corner of the site to less than 180 feet in the northwest part of the site. A comparison of the stream elevation to the seepage and springs elevations indicates that the seepage elevation is not lower than the elevation of the stream. Thus, the stream does not appear to provide recharge to the seepage and springs at elevations of 220 to 230 feet on the west -facing slope. The source of these springs and seeps appears to be local precipitation and recharge from higher areas to the south and southeast. 2.3 Wetlands r One wetland and one stream are located on the site. The wetland edges and the stream were delineated by Pacific International Engineering, P.L.L.C. (PIE), in May 1998 (PIE, 1998). The wetland and stream areas delineated by PIE were surveyed and plotted by David Evans & Associates, Inc. (DEA), and appear in Plate 2 - Site Plan and Plate 3 Development Plan. Wetlands on the site total 1.12 acres. The wetland is channelized near the northwest corner of the site and is more accurately described as a stream. Off -site to the west the water resource continues as a stream. Off -site to the northeast, the wetland edge is disturbed and bounded by a storm drainage line and fill from residential yards. Thus, the majority of the wetland is located within the Sequoia Ridge site. The majority of the wetland consist of mixed palustrine, forested, scrub -shrub wetland. Within 1, the stream corridor and flood zone, the wetland meets the definition of a riverine, forested, scrub - shrub classification. Small areas of uplands are located within some parts of the wetland. These upland areas appear to be both natural knolls and remnants of site manipulation (road fill, side cast, and fill piles) and are included within the wetland boundaries. Under ECDC regulations, the wetland meets the criteria to be classified as a Category 2 wetland due to its size (greater than one acre) and presence of two or more wetland classes. Under this Geo Group Northwest, Inc. 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 8 classification, a 50-foot wide buffer is required adjacent to the wetland edge and a 15-foot 41 building setback area is required beyond the wetland buffer area. A small stream (Meadowdale Creek) enters the site at the northeast side of the site. This stream appears to be supported by storm water from the unopened right-of-way for 72°d Avenue West and from groundwater seeps in the wetland areas on site. This stream appears to have been ditched through the wetland. The stream channel terminates at a catch basin under North Meadowdale Road. The stream flow eventually discharges to Brown's Bay in Puget Sound. No evidence of fish presence has been observed in the stream on site. This stream is not identified in the Washington Department of Fish and Wildlife "Catalog of Washington Stream i and Utilization -Puget Sound". The stream is not likely to be an anadromous fisheries stream due to the presence of downstream barriers. Parts of this riparian area also include the wetland areas identified as riverine, forested, scrub - shrub habitat. The stream channel shows evidence of carrying "flashy" flows due in large part to the storm water discharge from off site to the east. The stream channel is vertical sided, incised in several locations, and lacking vegetation along the steepest sidewalls of the ditch. The stream appears to be perennial, carrying water from groundwater discharge and flow from the wetland. Under ECDC regulations, this stream meets the criteria for classification as a Category 2 Stream. ECDC regulations require a 25 foot buffer adjacent to a Category 2 stream and a 15-foot building setback area beyond the stream buffer area. 2.4 Geologic Hazards 2.4.1 Erosion Hazard 7 The soil types present on the proposed project site have moderate to high erosion potential, according to the SCS soil survey (SCS, 1983). The Alderwood soils at the site have medium erosion potential and are susceptible to sheet wash and rill erosion, if exposed. The Everett soils at the site have high erosion potential and are susceptible to sheet wash, rill, and gully erosion. 1' Geo Group Northwest, Inc. i t 1 1 1 L' 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 9 Based on site observations during geotechnical studies in May 1999 and historical experience in the Puget Sound region, Geo Group Northwest, considers the advance outwash sand (Everett) soils at the site to have a high erosion potential. The silty (Alderwood) soils associated with the on -site areas underlain by glacial till are considered to have a low to moderate erosion potential, when exposed. Geo Group Northwest, Inc. anticipates that the soils in the wetlands area on site have relatively lower susceptibility to erosion due to the relatively lesser slopes and the thick cover of vegetation. The City of Edmonds Community Development Code (ECDC) identifies areas with Alderwood or Everett Series soils on slopes of 15 percent or greater as erosion hazard areas (ECDC Section 20.15B.060(A)(3)(a)). Based on this criterion, the sloped portions of the project site underlain with glacial till and advance outwash soils (Lots 1, 2, and 3, and the proposed building location on Lot 4) are erosion hazard areas. The flat area on the southwest corner of the site is not an erosion hazard area by this criterion. 2.4.2 Steep Slope and Landslide Hazards The site has moderate to steep slopes across its west, north, and east -central parts. The steepest slopes are found in the western part of the site on Lots 2, 3, and 4. The slopes in this part of the site tend to be irregular in steepness, and much of the slope is obscured by thick vegetation. The steepest slopes on the site reach near -vertical inclinations of about 60 degrees. According to the geotechnical reports by RLA (RLA, 1979) and GeoEngineers (GeoEngineers, 1985), the steep slopes along the southwest part of the proposed project site have a 5 percent probability of failure within 25 years, and the slopes in the north and northeast part of the site have a 2 percent probability of failing within 25 years. The reports characterize the landslide risk in the west part of the site as involving slumps of material that has not previously failed. The landslide risk in the north and northeast parts of the site are characterized as debris slides in material that has not previously failed. The criteria used in these reports for determining the landslide risk included steepness of slope, height of slope, soil types, presence and character of evidence of previous landsliding, and presence of groundwater seepage or springs. Landslide hazard areas are shown on Plate 7 - Landslide Hazard Map. Geo Group Northwest, Inc. 1 i February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 10 The ECDC incorporates by reference the landslide hazard findings in the GeoEngineers and RLA reports (ECDC Section 20.15B.060(A)(3)(b)). The ECDC also defines landslide hazard areas as those areas that have interbedded permeable and impermeable soils, groundwater springs or seepage, and slopes of 15 percent or greater. Based on these criteria, the steep west -facing slope on the site is a landslide hazard area. 2.4.3 Seismic Hazard The project site is located within the Puget Sound Lowland. The greater Puget Sound area has experienced a number of small to moderate earthquakes and occasional strong shocks during the brief 155-year historical record in the Pacific Northwest. The major earthquakes in the region are believed to be associated with deep-seated plate tectonic activity. Major faults within the region i have not been active in the Holocene Age (geologic period dating since the last glacial retreat 14,000 years ago), consequently, none are known to be associated with historical seismicity. i Historical records for the region indicate that the Olympia earthquake of April 13, 1949, with a Richter magnitude of 7.1, produced ground -shaking of intensity VIII near its epicenter; and the Seattle -Tacoma earthquake of April 29, 1965, with a Richter magnitude of 6.5, produced a ground -shaking of intensity IV to VIII on the Modified Mercalli Scale near its epicenter. This level of ground -shaking is estimated to be the maximum that has occurred in the region during the 155 years of historic record. The ECDC identifies seismic hazard areas as those area which are subject to severe risk of earthquake damage as a result of seismically induced landslides, earth adjustments (such as displacement by faulting), settlement, or liquefaction (ECDC Section 20.15B.060(A)(3)(d)). Liquefaction is a phenomenon where loose granular materials below the water table temporarily behave as a liquid due to. strong shaking or vibrations, such as earthquakes. Clean, loose and saturated granular materials are the soils susceptible to liquefaction phenomena. During our site investigation, subsurface. soils consisted of medium dense to dense, fine grained sand (advance outwash) and silty sand with gravel (glacial till) on Lots 1, 2, and 3. Groundwater was encountered at approximately 30 feet bgs in boring B-3 on Lot 3. Light seepage was observed at depths of 2 to 3 feet bgs on top of dense glacial till soils in boring B-2 on Lot 2. No groundwater was encountered in boring B-1 on Lot 1. Subsurface soils encountered in boring B- Geo Group Northwest, Inc. i February25 2000 , G- 1061 1 Mr. John Thoresen - Sequoia Ridge Partners Page 11 4 on Lot 4 consisted of medium dense to dense silt, silty sand, and fine grained sand. Wet soils were encountered at approximately 6 feet bgs in boring B-4, but the predominant silt and silty sand are not soil types susceptible to liquefaction. Thus, subsurface soils the proposed building locations on site are not susceptible to liquefaction, based on the observed soil types, densities, and moisture contents. The saturated soils in the northeast part of the site (where wetlands have been identified) may be susceptible to liquefaction because of the presence of shallow groundwater conditions and the possible presence of fine sandy soils below the surficial layer of organic soils. The potential hazard is not considered to be a significant concern for the proposed development, however, because this part of the site will not be developed. Based on these criteria, the areas of the site proposed for development are not considered to contain seismic hazard areas. 2.5 Geologic Hazard Area Buffers and Setbacks The ECDC requires a 50 feet wide buffer for geologically hazardous areas, including erosion, landslide, and steep slope hazard areas (ECDC Section 20.15B.110(A)). The width of the buffer can be reduced to as low as 10 feet if it can be demonstrated that the proposed buffer alteration will have no adverse impact on the site, City, or any private party. The ECDC also requires that a 15 feet wide building setback be established from the edge of any buffer, including buffers for geologic hazards, to prevent construction intrusion into the buffer (ECDC Section 20.15B.080 i (Q. Thus, the minimum total distance between the proposed buildings and geologic hazard areas is 25 feet. Alterations within erosion hazard areas require City approval of an erosion control plan that minimizes disruption of soils to the minimum degree necessary to provide reasonable use of the site (ECDC Section 20.15B.110(B)). Alterations in steep slope hazard areas require an ' exemption or exception pursuant to ECDC Section 20.15B.040, or a variance pursuant to ECDC Section 20.15B.170. Categories for exemption or exception include situations where critical areas studies had previously been prepared for the type of proposed development, and reasonable use exceptions where application of the critical areas regulations would deny all reasonable use of the property. Categories for variance also include situations where critical areas regulations would deny the reasonable use of the subject property. Geo Group Northwest, Inc. 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 12 The ECDC Chapter 20.15B specifies that a 50 feet wide buffer and a 15 feet building setback be established for geologically hazardous areas (such as steep slope and landslide areas). The buffer can be reduced to 10 feet if it can be demonstrated that the proposed buffer reduction will have no adverse impact on the site, public, or any private party. 3 CONCLUSIONS AND RECOMAMNDATIONS 3.1 General Based on a review of the available information for the proposed development, Geo Group Northwest concludes that the site is geotechnically suitable for development into a four -lot residential subdivision as proposed, provided that the development is designed and constructed in a manner that minimizes impacts to the site that could adversely affect site stability. Issues of primary geotechnical concern include establishing appropriate building setback distances from the steep west -facing slope on the site, controlling soil erosion during and following site development, using deep foundation systems for the proposed residences to mitigate impacts from future sloughing along the steep slope on site, and constructing a driveway across the stream at the north end of the site. As a result, we recommend the following measures be a incorporated into the design and construction of the proposed development: • support the homes on Lots 2, 3, and 4 entirely on deep pile foundation systems; • configure residences on slopes to minimizing grading, where feasible; • support fills below the driveways with modular block walls and geogrid reinforcement, and support cut slopes with rockeries or concrete retaining walls; and • perform daily, on -site, geotechnical quality control monitoring of erosion and sedimentation control measures, earthwork activities, pile installation, driveway and roadway construction activities, underground utilities installation and backfilling, site stability, and other aspects as required by the City of Edmonds. These items and other eotechnical issues involved in the proposed development g p p p ent are discussed in 1 detail in the following sections of this report. Geo Group Northwest, Inc. LI J February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 13 3.2 Site Stability Evaluation In their preliminary geotechnical study, NCA recommended that a 15 feet wide setback be established between the top of the steep west -facing slope and any buildings. It is the opinion of Geo Group Northwest, however, that a 15 feet wide setback will be suitable for Lots 3 and 4, but that a setback of 25 feet should be established for Lot 2, where the steep west -facing slope is higher. These recommended setbacks for Lots 2, 3, and 4, should be conditioned on the requirement that the residences on these lots be supported on deep-seated pile foundation systems. Our rationale for these proposed buffer/setbacks is as follows: • Based on the findings from the site investigation work performed by Geo Group Northwest, Inc. in May 1999, dense soils are present at depths of approximately 5 feet bgs at each of the proposed building locations. The depth to groundwater at the proposed building locations ranges from approximately 6 feet on Lot 4 to 30 feet bgs at Lot 3, to depths greater than 30 feet bgs on Lots 1 and 2. The geotechmcal reports by Roger Lowe Associates (1979) and by GeoEngineers, Inc. (1985), have described a lack of recorded, historical large-scale landsliding on the steep west -facing slope at the site, but have also noted that historical records of past landslide events are incomplete. The owner of the adjacent property south of the site, Mr. John Johnson, has reported that no landslides have occurred on the slope during his residence in the area (approximately 40 years). • Geo Group Northwest believes it is possible for the proposed buildings to be located at minimum distances of 15 to 25 feet from the top of the steep west -facing slope (15 feet on Lots 3 and 4, 25 feet on Lot 2), if the buildings are supported on deep foundation systems that are embedded in soils that less susceptible to future sloughing along the nearby steep slope. The proposed residence on Lot 1, however, can be supported on shallow conventional spread footing foundation systems, provided that the residence is located at least 50 feet from the top of the steep slope. ' As discussed in the Limited Scope Environmental Impact Study prepared by Geo Group Northwest in 1999 (Geo Group Northwest, 1999), steep slope and landslide hazard areas on Lots 2, 3, and 4 at the site can be protected from potential impacts by establishing 15 to 25 feet wide Geo Group Northwest, Inc. February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 14 building setbacks zone from the top of the steep west -facing slope on the site. The recommended setbacks have been approved by the City of Edmonds through a review of the EIS by the City Hearing Examiner. The proposed development incorporates such setbacks for these lots. —i It is the opinion of Geo Group Northwest that p p the proposed development, utilizing the proposed 15 and 25 feet setbacks from the top of the steep slope, will not affect the site stability during or following construction, provided the recommendations provided in this report are followed. 3.3 Site Preparation and Earthwork To minimize the amount of site grading for construction of the proposed residences, the building pads should be step -graded to where dense native soils are exposed. Split-level building floors could be incorporated into the construction plans and design to accommodate the topographic relief across the proposed building locations. This would require the, removal of minimal amounts of loose soils on Lots 1 and 2, and removal of about 5 feet of loose soils on Lots 3 and 4. The areas between the residences should be graded to permanent slopes no steeper than 2Horizontal: I Vertical (2H:1 V); alternatively, rockeries and modular block retaining walls can be used to accommodate changes in grades, where available space would require steeper slopes. The building, driveway, and sidewalk areas should be stripped and cleared of surface vegetation. Disturbance to the site should be kept to a minimum. Silt fences should be installed around areas disturbed by construction activity to prevent sediment -laden surface runoff from being discharged off -site. Exposed soils that are subject to erosion should be compacted or covered with plastic sheeting, or both. The surficial topsoil and loose sand soils below the proposed building foundation areas should be excavated down to dense, native soil. Based on the fmdings from our soil investigation at the site, we anticipate that the medium dense to dense soil under the building area is present at ' approximately 3 feet bgs. Based on these findings, some over -excavation and replacement of the loose to medium dense silty sand soils with structural fill may be required. After the loose soils are excavated, we recommend that the bottom of the excavation be compacted and proof -rolled with a piece of heavy construction equipment. Any soft spots or disturbed areas thus detected should be re -compacted or excavated and replaced with compacted Geo Group Northwest, Inc. 1 1 1 1 1 1 1 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 15 structural fill. To protect underground utilities from settlement, we recommend that the bottom of utility trenches be compacted using a backhoe-mounted "hoe -pack". City of Edmonds regulations (ECDC 20.15B.080(A)(1)) prohibit site clearing activities in critical areas (including geologically hazardous areas, erosion hazard areas, steep slope areas, and sensitive habitat areas) between October 1 and April 30. An appeal process exists for requesting a variance from this regulation (ECDC 20.15B.040). The City of Edmonds does allow for weekly consultation from the project geotechnical engineer on whether earthwork can continue past September 30. We recommend that Geo Group Northwest be retained to monitor site earthwork and consult with Sequoia Ridge Partners and the City of Edmonds, in the event that a variance to continue earthwork past September 30 is requested. 3.3.1 Temporary Slopes and Excavations Under no circumstances should temporary excavation slopes be greater than the limits specified in local, state and national government safety regulations. Temporary cuts greater than four feet in height should be sloped at an inclination no steeper than 1 H:1 V (Horizontal:Vertical) in the weathered glacial till and no steeper than 1H:2V in the dense glacial till soils. Permanent fill slopes at the site should be inclined no steeper than 211:1 V. Surface runoff should not be allowed to flow uncontrolled over the top of slopes into the excavated area. During wet weather exposed cut slopes should be covered with plastic sheeting during construction.to minimize erosion. If groundwater seepage is encountered during construction, excavation of cut slopes should be halted and the cut slopes should be re-evaluated by Geo Group Northwest, Inc. 3.3.2 Subgrade Stabilization The silty sand soils encountered in the borings on Lots 2 and 4 are moisture sensitive and may prove to be unsatisfactory as a subgrade base for the pavements, slabs, and structures if earthwork takes place during wet weather conditions. We recommend using either or both of the two following methods for subgrade stabilization: 1) bridging the soft subgrade soils; or 2) cement treating the soils. Geo Group Northwest, Inc. 1 1 1 1 1 1 1 1 1 1 February 25, 2000 � [00181 Mr. John Thoresen - Sequoia Ridge Partners Page 16 3.3.2.1 Bridging Soft subgrade conditions can be stabilized by bridging with an 18-inch minimum thickness of 2- inch minus crushed rock, or a 24-inch thickness of class A pit run. A woven geotextile fabric, such as Mirafi 500X or equivalent, should be laid below the bridging soils to provide base reinforcement, separation and stabilization. Areas of additional rock/pit run thickness may be needed depending on the subgrade conditions at the time of construction. Standing water should be pumped or drained prior to placement of the geotextile and bridging soils. It should be noted that bridging may require over -excavation and export of the over -excavated spoils, depending on the planned final site grades. The cost of over -excavation and export and disposal of the over -excavated soils should be considered in the decision to over -excavate and bridge or to cement treat unsuitable subgrades. Over -excavation and export can be minimized by raising the finished site grades or by cement treating the subgrade. 3.3.2.2 Cement Treatment Unsuitable subgrade soils at the site can be cement treated, instead of excavated and replaced. In general, cement treatment should provide a minimum 12-inch thickness of cement treated base (CTB) or extend down to firm soils, whichever is encountered first. The site should be pre - graded prior to treatment to prevent cutting or removing the minimum thickness of CTB during the final grading process. The final, post -grading CTB thickness should be at least 12 inches. The rate of application of the cement is dependent on the soils moisture content and may vary from about 4 percent to 8 percent ( 43 lbs to 86 lbs per square yard by 1-foot deep). We anticipate that a 5 percent cement content or an application rate of 6 pounds per square foot (54 lbs per square yard) would be used at the site. It should be noted that site traffic of equipment, trucks, backhoes and forklifts can soften areas treated with cement. Yielding subgrade areas should be evaluated by the geotechnical engineer and if necessary we recommend applying additional cement treatment, or over -excavating and replacing with imported structural fill, underlain by geotextile fabric. It should also be realized that the cement treatment base can harden to the point of having an impact on later site utility work, especially if higher cement application rates are used. We recommend that the CTB be Geo Group Northwest, Inc. I February0, 25 2000 � G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 17 protected from site traffic by covering with a minimum of 4-inches of 5/8 inch minus crushed surfacing top coarse or other imported soil approved by the geotechnical engineer. 3.3.3 Structural Fill All structural fill material used to achieve design site elevations below the building area and below non -structurally supported sidewalks, driveways, and patios, should meet the requirements for structural fill. During wet weather conditions, material to be used as structural fill should ' have the following specifications: I 1. Be free draining, granular material containing no more than five (5) percent fines (silt and clay -size particles passing the No. 200 mesh sieve); I 2. Be free of organic material and other deleterious substances; 3. Have a maximum size of three (3) inches in diameter. I All fill material should be placed at or near the optimum moisture content. The optimum moisture content is the water content in soil that enables the soil to be compacted to the highest dry density for a given compaction effort. We anticipate that the on -site silty sand soils will be moisture -sensitive and will be unsuitable for ' use as structural fill if they become wet. These soils should be suitable for use as structural fill as I long as they are placed at or near their optimum moisture content. Alternatively, an imported granular fill material may provide more uniformity and be easier to compact to the specifications for structural fill. The fine to medium grained sand soils without silt should be suitable for use as structural fill under anticipated site conditions. If the on -site soils are to be used as engineered structural fill, it will be necessary to segregate the topsoil and any other organic- or debris -containing soil, because such soils would be unsuitable for use as structural fill. Excavated on -site material that is stockpiled for later use as structural fill should be protected from moisture or contamination with unsuitable materials by covering it with plastic sheeting until it is used. Structural fill should be placed in thin horizontal lifts not exceeding ten inches in loose thickness. Structural fill under building areas (including foundation and slab areas), should be compacted to Geo Group Northwest, Inc. 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 i 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 18 at least 95 percent maximum density, as determined by ASTM Test Designation D-1557-91 (Modified Proctor). Structural fill under driveway areas should be compacted to at least 90 percent of maximum density, with the exception of the upper twelve (12) inches. The top twelve (12) inches should be compacted to at least 95 percent maximum density, as determined by ASTM Test Designation D-1557-91. Poor quality subgrade conditions are anticipated in the location of the existing sewer line trench. For this reason, we recommend that the fill section over the trench area consist of 18 inches of clean, 2-inch sized, crushed rock wrapped with a geotextile filter fabric such as Mirafi 140NL or equivalent. We also recommend that the driveway fill consist of a free -draining pit run sand and gravel or a clean crushed rock material. We recommend that Geo Group Northwest be retained to evaluate the suitability of structural fill material and to monitor the compaction work during construction for quality assurance of the earthwork. 3.3.4 Pipe Bedding The pipe and pipe bedding interact to form a soil structure system; therefore, the bedding support requirements differ for flexible and rigid pipes. Our recommendations for pipe bedding materials follow the 1996 Standard Specifications for Road, Bridge and Municipal Construction, published by Washington State Department of Transportation and American Public Works Association (APWA) Specifications Sections 9-03.15 and 9-03.16. Any changes to these material specifications must be approved by the geotechnical engineer. Bedding material should be placed between at least 6 inches below the base of the pipe and at least 6 inches above the top of the pipe. Bedding material shall have a maximum dimension of 1.5-inches in diameter and shall be a clean sand and gravel mixture free of organic matter and fines (material passing a #200 sieve), conforming to the following gradations: Geo Group Northwest, Inc. 1 February 25 2000 Mr. John Thoresen - Sequoia Ridge Partners G-1061-1 Page 19 WSDOT/APWA Specifications'Section 9�03.IS :Bedding.for Rigzd:Pipe 7TUS. Sieve Size Percent Passing (by weight) 1-inch square 100 1/4-inch square 25 - 80 No. 200 7 max. Sand Equivalent 35 min WSDOT/APWA, Specifications Section; 9-03.16 Bedding for`T4er*plastic Pike (Flexible Pipe) U.S. Sieve Size Percent Passing (by weight) 3/4 inch square 100 3/8-inch square 70 - 100 No. 4 55 - 100 No. 10 35 - 95 No. 20 20 - 80 No. 40 10 - 55 No. 100 0 - 10 No. 200 0-3 All pipe bedding materials should be compacted to provide the lateral support needed for the pipe. However, caution should be exercised when compacting the soils in the vicinity of non - reinforced pipe to prevent damage to the pipe. 3.3.5 Trench Backfill Trench backfill (above the pipe bedding materials) beneath concrete slabs and pavement areas may consist of native soils, provided the backfill can be compacted to the specified compaction Geo Group Northwest, Inc. i February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 20 criteria. The backfill should be placed in lifts of approximately 8 inches in un-compacted thickness. If the native soils cannot be compacted to the specified compaction standard, we recommend that a suitable imported structural fill material be used. During wet weather, we recommend using a pit -run sand and gravel material with 100 percent smaller than 3-inches in diameter and less than 5 percent passing a #200 sieve. Trench backfill beneath pavement areas and sidewalks should be placed and compacted according to the recommendations for structural fill. Trench backfill should be compacted to a minimum of 90 percent of maximum density according to ASTM D1557-91 (Modified Proctor), and to 95 percent of the maximum dry density for the top 12-inches. 3.4 Erosion and Sedimentation Control The west and center parts of the site are the most susceptible to erosion impacts, since these areas have the steepest slopes on the site, are underlain generally with Alderwood and Everett soils, and are the areas proposed for development. Uncontrolled runoff during construction could i impact surrounding areas in the form of erosion, sloughing, and sedimentation. Sloughing or ' erosion along the steep slopes on the west side of the site could result in sediment or slough debris traveling onto the adjacent property west of the site. Sediments eroded from cleared land on Lot 4 could reach the nearby stream if not controlled. Measures to control erosion and sedimentation impacts can be implemented during construction. ' Typical measures would include application of General Development Standards as outlined in ECDC Chapter 18.30, and implementation of an Erosion and Sedimentation Control Plan (ESCP) per ECDC requirements. 3.4.1 General Development Standards Anticipated impacts to soil during construction can be mitigated by application of General Development Standards pursuant to ECDC Chapter 18.30. These standards include: Clearing shall occur only during the dry season of May 1 through September 30, unless authorized by the project geotechnical engineer and agreed to by the City. Extensions of Geo Group Northwest, Inc. 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 21 clearing activities beyond September 30 can be recommended by the project geotechnical ,j engineer, where appropriate, and approved by the City on a weekly basis. No clearing shall be allowed within protected critical areas, including buffers, as approved by the City and identified by survey on the Final Short Plat map. • Prior to start of construction, the approved, protected critical areas and buffer areas shall be protected with temporary fencing. I • All utilities, including grading for utilities shall be located outside the approved protected i critical areas and buffer areas. ,j All structures, including grading for structures, shall be located outside the steep slope i setback line approved by the city during the short plat review process. • A site specific management plan for both temporary sediment and erosion control and permanent storm water management shall be prepared and approved by the city for protection of the wetland, stream, and buffers in accordance with the ECDC Storm Water Management standards. 1 3.4.2 Erosion and Sedimentation Control Plan The ECDC requires the preparation and implementation of an Erosion and Sedimentation ' Control Plan (ESCP) for construction projects located in critical areas (including steep slope r hazard, erosion hazard, and wetland areas). The ESCP shall be approved by the City of Edmonds, and implemented pursuant to ECDC Chapter 18.30. Minimum requirements for an ESCP include, but are not limited to, the following: 1 • Construction vehicle access shall be limited to one route, whenever practical (for the proposed development, two routes would be most practical —one route from North Meadowdale .Road for Lot 4, and one route from 72"d Avenue West for the remaining lots). The route(s) shall be stabilized with quarry spalls or crushed rock. • Adjacent properties shall be protected from sediment deposition by appropriate use of vegetative buffer strips, sediment barriers or filters, dikes or mulching, or combination of these measures and other appropriate BMPs. • Cover exposed soils that will be left unworked either overnight or over longer periods of time during rainy periods; at a minimum, no soils should be exposed for more than two days from October 1 to April 30. • Regular inspection and maintenance of BMPs. Geo Group Northwest, Inc. 1 1 1 1 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 22 Delineate clearing and easement limits including setbacks, critical areas and buffers, and trees. Limit construction traffic to access roads and designated traffic areas and provide designated areas for staging equipment, to minimize the area of soil disturbance. Re -vegetate disturbed areas as soon as practical following grading, and stabilize newly vegetated areas with mulch, straw, or jute netting until vegetation is established; do not remove BMPs until disturbed areas are stabilized. Drainage off impervious areas (building roofs and pavements) would be directed to catch basins and tightlined to discharge to the storm drainage line below North Meadowdale Road. Drainage off the roadway and driveways also would be treated by being passed through an oil/water separator before being discharged. Water associated with drainage behind retaining structures (such as walls that support proposed driveways and cut slopes, and rockeries greater than 4 feet in height) also can be tightlined into the storm drain system, instead of being discharged to site soils. A decrease of the infiltration rate into site soils could result in a marginal decrease in the groundwater elevations at the site and thereby slightly increase the stability of the slopes on site. 3.5 Foundations 3.5.1 Deep Foundation Systems The proposed buildings can be supported on a pile foundation system such as augered concrete piles. The piles would be embedded deeply into the dense soils so that they transfer the building loads to deeper soils which are less susceptible to sloughing along the nearby slope. Placing the buildings on a deep pile foundation system will significantly help to protect the buildings from potential damage from possible future sloughing along the top of the steep slope (which could be anticipated to occur over the long term even if no development occurred on the site). We recommend that the piles be installed to a minimum depth of 25 feet into the dense, native soils. However, specific geotechnical recommendations for pile lengths at each proposed building location should be further studied during the design of the residences and after the topography of the steep west -facing slope is better defined. We recommend that the piles have a minimum diameter of 14 inches. The piles should have a minimum allowable bearing capacity Geo Group Northwest, Inc. 1 1 1 1 A 1 1 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 23 of 25 tons, as calculated based on the encountered soil conditions in the soil borings drilled on site. Lateral loads can also be resisted by using battered piles or by the passive earth pressures acting on grade beams. To fully mobilize the passive pressure resistance, the grade beams must be poured "neat" against compacted fill. Our recommended allowable passive soil pressure for lateral resistance is 300 pcf equivalent fluid weight, with a friction factor of 0.3. The performance of piles depends on how and to what bearing stratum the piles are installed. Since a completed pile in the ground cannot be observed, it is critical that judgement and experience be used as a basis for determining the embedment length and acceptability of a pile. Therefore, we recommend that the project geotechnical engineer be retained to monitor the pile installation operation, collect and interpret installation data and verify suitable bearing stratum. We also, suggest that the geotechnical engineer review the contractor's equipment and installation procedure prior to pile installation to help mitigate problems which may delay work progress. 3.5.2 Shallow Foundation Systems An alternative to constructing deep foundations for the proposed buildings is to create building pad areas on which the buildings could be constructed with shallow, conventional spread footing foundation systems. The existing soils below the proposed building locations have adequate bearing strength to support typical shallow conventional spread footing foundations, after the surficial loose soils are removed. However, the springs, seepage, and visual evidence of previous small slumps and sloughing on the steep west -facing slope indicate a potential exists for future sloughing or slumps to occur along the slope. Future sloughing or slumps could adversely affect structures placed on shallow foundations. The use of shallow foundation systems, such as conventional spread footings, should be limited to buildings which will be located at least 50 feet from the top of the steep west -facing slope (such as the proposed residence on Lot 1). Loose or soft soils below the foundation footings should be excavated down to dense soil and the over -excavated areas should be replaced with compacted structural fill. Based on the findings from our soil investigation at the site, we anticipate that medium dense to dense native soil under the building area is present at approximately 3 feet bgs. Geo Group Northwest, Inc. 1 I., February 25 2000 1 1 1 1 1 1 1 1 1 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 24 Individual spread footings may be used for supporting columns and strip footings for bearing walls. Our recommended design criteria for foundations are as follows: - Allowable bearing pressure, including all dead and live loads Dense native soil (glacial till) = 2,000 psf Compacted structural fill = 2,000 psf - Minimum depth to bottom of perimeter footing below adjacent final exterior grade = 18 inches - Minimum depth to bottom of interior footings below top of floor slab = 12 inches - Minimum width of wall footings = 16 inches - Minimum lateral dimension of column footings = 24 inches - Estimated post -construction settlement = 1 /4 inch - Estimated post -construction differential settlement; across building width = 1/4 inch A one-third increase in the above allowable bearing pressures can be used when considering short-term transitory wind or seismic loads. Lateral loads can also be resisted by friction between the foundation and the supporting compacted fill subgrade or by passive earth pressure acting on the buried portions of the foundations. For the latter, the foundations must be poured "neat" against the existing undisturbed soil or be backfilled with a compacted fill meeting the requirements for structural fill. Our recommended parameters are as follows: - Passive Pressure (Lateral Resistance) • 300 pcf equivalent fluid weight for compacted structural fill • 350 pcf equivalent fluid weight for native dense soil. Geo Group Northwest, Inc. A - February 25, 2000 G 1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 25 - Coefficient of Friction (Friction Factor) • 0.30 for compacted structural fill 0.35 for native dense soil We recommend that footing drains be placed around all perimeter footings. More specific details of perimeter foundation drains are provided below in Section 3.10: Drainage. 3.6 Building Floors The buildingfloors can be supported on either the dense native soils at the site where PP ( conventional footing foundations are used), or can be structurally supported on a pile foundation system. In preparing the subgrade for slab -on -grade floors, any areas of the building pad disturbed by construction activity should be either re -compacted or excavated and replaced with ' compacted structural fill material. We recommend the building pad area be proof -rolled with a piece of heavy construction equipment prior to placing the capillary break material. Any soft or low areas thus detected should be filled to grade and re -compacted or excavated, and replaced and'compacted with crushed rock as described in Section 3.3 : Site Preparation and General Earthwork. To avoid moisture build-up on the subgrade, slab -on -grade floors should be placed on a capillary break, which is in turn placed on the prepared subgrade. The capillary break should consist of a minimum of a six (6) inch thick layer of free -draining crushed rock or gravel containing no more than five (5) percent finer than No. 4 sieve. A vapor barrier, such as a 6-mil plastic membrane, is recommended to be placed over the capillary break beneath the slab to reduce water vapor transmission through the slab. Two to four inches of sand may be placed over the barrier membrane for protection during construction. 3.7 Permanent Basement and Conventional Retaining Walls Permanent basement walls restrained horizontally on top are considered unyielding and should be designed for a lateral soil pressure under the at -rest condition; while conventional reinforced concrete walls free to rotate on top should be designed for an active lateral soil pressure. 1 Geo Group Northwest, Inc. 1 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 26 Active Earth Pressure Conventional reinforced concrete walls that are designed to yield an amount equal to 0.002 times the wall height, should be designed to resist the lateral earth pressure imposed by an equivalent fluid with a unit weight of: • 35 pcf for level backfill behind yielding retaining walls; At -Rest Earth Pressure Walls supported horizontally by floor slabs are considered unyielding and should be designed for lateral soil pressure under the at -rest condition. The design lateral soil pressure should have an equivalent fluid pressure of: • 45 pcf for level ground behind permanent unyielding retaining walls; Passive Earth Pressure • 300 pcf equivalent fluid weight for structural fill • 350 pcf equivalent fluid weight for native soil Base Coefficient of Friction • 0.30 for structural fill • 0.35 for native soil We recommend that a vertical drain mat, Miradrain 6000 or equivalent, be used to facilitate drainage behind permanent concrete basement walls. The drain mat core is placed against the basement wall with the filter fabric side facing the backfill. The drain mat extends from the finished surface grade, down to the footing drain pipe. A minimum of 18 inches of clean, free - draining, washed rock, crushed rock, or pea gravel should be placed in the bottom of the footing trench. With the above exceptions, perimeter foundation drainage recommendations and installation procedures should be followed in Section 3.10.2: Footing and Wall Drains. Please also refer to Plate 9 - Typical Basement Wall Backfill and Drainage Details. To prevent buildup of hydrostatic pressure behind permanent concrete basement or conventional retaining walls, a granular, free draining structural backfill material should be placed within a horizontal distance of 18 inches of the wall, in place of vertical drain mats. We recommend Geo Group Northwest, Inc. 1 1 1 1 1 1 1 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 27 using a clean, granular, free -draining, structural fill material. The free -draining granular material should surround the wall subdrain system as described in the footing drain section of this report. The top twelve (12) inches of the fill should consist of compacted and relatively impermeable soil. This cap material can be separated from the underlying more granular drainage material by a geotextile fabric. The surface should be sloped to drain away from the building wall. Alternatively, the surface can be sealed with asphalt or concrete paving. Backfill material behind permanent concrete basement or conventional retaining walls should be compacted to 90 percent of the maximum dry density determined by ASTM D 1557-91 (Modified Proctor Method) as specified in Section 3.3.3: Structural Fill. The top 12-inches should be compacted to 95 percent of the maximum dry density. The backfill in areas adjacent to basement or conventional retaining walls should be compacted with hand held equipment or a hoe -pack. Heavy compacting machines should not be allowed within a horizontal distance to the wall equivalent to one half the wall height, unless the walls are designed with the added surcharge. 3.8 Modular Block Walls We understand that a retaining wall will be required along the south side of the driveway for support. The proposed wall is anticipated to be approximately 125 feet long and up to approximately 8 feet high. This wall may consist of either a conventional concrete retaining wall founded on the dense glacial till soils, or a modular block wall with geogrid reinforcement set on the dense glacial till soils. Design parameters for a conventional retaining wall are presented in Section 4.7: Permanent Basement and Conventional Retaining Walls. The modular cement block wall can consist of keystone walls or ecology block walls and should include reinforcement by geogrid layers embedded in compacted structural fill. The wall base pad should be prepared by excavating a trench into dense, bearing soil. The cement blocks should then be stacked on a 6-inch thick layer of free -draining crushed rock. Steps should be excavated on the existing slope behind the wall to allow the backfill to interlock with the existing soils. The wall should be designed using the following parameters: Geo Group Northwest, Inc. February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 28 Friction Angle (phi): 35 degrees Unit Weight (gamma): 130 pcf A wall drain should be installed behind the wall. The drain should consist of a 4-inch diameter perforated PVC pipe placed at the inside base of the wall. The pipe should be surrounded by a free -draining crushed rock and geotextile fabric as illustrated in Plate 8 - Typical Basement Wall Backfill and Drainage Details, and tightlined to a suitable discharge location away from the wall (such as the local storm drain system). The drain should extend the entire length of the wall and be installed at a grade sufficient to maintain flow to the tightline. The geogrid layers should be attached to the cement blocks and embedded within a compacted structural fill material. Backfill behind the wall shall consist of free -draining structural fill material that meets the compaction requirements in Section 3.3.3: Structural Fill. 3.9 Rockeries It should be understood that a rockery is not intended to function as an engineered structure to resist lateral earth pressures, as a retaining wall would be. The primary function of a rockery is to cover the exposed excavated surface and thereby retard the erosion process. However, some lateral support is provided by virtue of the weight of the rock. Therefore, the larger the rock the greater the mass and the more lateral load resistance available. However, since this support depends on the contact areas and characteristics between individual rocks, it is virtually impossible to predict or provide for a specific lateral resistance. Also, rockery construction is to a large extent a skilled craft not entirely controllable by engineering methods. Because of this, it is imperative that rockeries be constructed in a proper manner by contractors experienced in, and with a proven capability in, rockery construction, and in accordance with the guidelines specified by the Association of Rockery Contractors, presented in Appendix B to this report. Rock Specifications Where cut slopes less than six feet high, or fill slopes less than four feet high exist, rockeries may be constructed entirely of four -man rock. Rockeries placed in front of six to eight feet high cut slopes should have one basal course of six -man rock. Rockeries with a height of eight to ten feet Geo Group Northwest, Inc. 1 A 1 1 1 i 1 1 1 1 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 29 should have at least two basal courses of six -man rock. For rockeries with a height of 10 to 12 feet, there should be at least three basal courses of six -man rock. The remaining courses may be four -man rock. The rock should be hard, sound, durable, free of seams and cracks, and broken in generally tabular to cubical shapes. Preferably, the rock density should be at least 165 pounds per cubic foot (pcf), but you should recognize rock densities will vary from source to source. Fills Behind Rockeries Any fills behind a rockery should consist of structural fill compacted to at least 95 percent relative compaction as determined by ASTM Test Designation D1557-91 (Modified Proctor). We do not recommend using rockeries in front of fills more than four feet high unless the fills have been reinforced with geogrids. Construction Procedure The initial step in rockery construction involves the excavation and preparation of a "keyway". This should be about six to eight feet wide, about 18 inches deep, and slightly inclined back in towards the face to be protected. The keyway should be excavated into dense, compacted soil capable of bearing the rockery. We recommend a shallow ditch, about 12 inches wide and deep, then be dug along the rear edge of the keyway. A four -inch minimum diameter perforated or slotted plastic drain pipe should be placed on and surrounded by a free -draining ballast or crushed rock. The pipe should be directed to a positive and permanent discharge. Once the exposed keyway subgrade has been prepared, the first basal layer of rock should be carefully "slammed" into place. These rocks should be placed in as close contact with each other as possible. Each row of rock should be well seated and thoroughly tamped and driven into place having as few voids as possible. Since the rockery derives its support partially from friction between individual rocks, point contact of rocks should be avoided wherever possible. Succeeding layers of rock should be placed so that rocks overlap each other. The face of the rockery wall should be inclined at a slope of approximately 1H:6V. The filter rock behind the rockery should be installed concurrently with the rockery. It should consist of a well -graded crushed angular rock with a three-inch maximum size. The filter layer should not be less than 12 inches in thickness. Geo Group Northwest, Inc. A 1 1 1, 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 30 Geotechnical Observation We recommend that the construction of the rockery (including placement of the rocks) be performed under our periodic observation. We will be available to meet with you and your rockery contractor to discuss these matters in more detail. 3.10 Site Drainage 3.10.1 Surface Drainage The finished ground at the site should be graded such that surface water is directed off the site. Water should not be allowed to stand in any area where footings, slabs or pavements are to be constructed. During construction, loose surfaces should be sealed at night by compacting the surface to reduce the potential for moisture infiltration into the soils. Final site grades should allow drainage away from the building. We suggest that the ground be sloped at a gradient of three (3) percent for a distance of at least ten feet away from the building except in areas that are to be paved. 3.10.2 Footing and Wall Drains We recommend that drains be installed around the perimeter of the foundation footings. The drains should consist of a four (4) inch minimum diameter, perforated or slotted, rigid drain pipe laid at or near the bottom of the footings with a gradient sufficient to generate flow, as schematically illustrated in Plate 9 - Typical Footing Drain. The drain line should be bedded on, surrounded by, and covered with a free -draining rock, pea gravel, or other free -draining granular material. Once the drains are installed, the excavation should be backfilled with a compacted structural fill material. The surface can be sealed with asphalt or concrete paving. Under no circumstances should roof downspout drain lines be connected to the footing drainage system. All roof downspouts must be separately tightlined to discharge into the storm water collection system. We recommend that sufficient cleanouts be installed at strategic locations to allow for periodic maintenance of the footing drains and downspout tightline systems. Geo Group Northwest, Inc. 1. February 25 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 31 3.11 Pavements ? We recommend the driveway subgrades be prepared as described in Section 3.3: Site Preparation and General Earthwork. Areas of soft, wet or unstable subgrade may still exist after this process. If so, over -excavation of the unsuitable material and replacement with compacted structural fill or crushed rock may be required. The overlying pavement section should consist of at least 3 inches of asphalt. The asphalt may be placed either directly over the crushed rock layer above the sewer line trench, or over a crushed rock base of at least 6 inches above other driveway areas. Alternatively, the pavement ' section can consist of a 2-inch thickness of asphalt concrete over a 3-inch thickness of asphalt treated base (ATB). 1 3.11.1 Driveway Support To minimize the width of the area that would be covered by the roadway, the roadway can be designed to include gravity retaining walls and rockeries to stabilize cuts and fills. The downslope (east) side of the roadway can be supported by a modular block wall reinforced with Geogrid layers placed in the underlying fills. Such a wall can be located adjacent to the east side of the roadway pavement (or about two feet out from the pavement edge to accommodate a guard rail) and can be constructed to be vertical or nearly vertical, as desired. Rockeries, Ecology block, or cast -in -place concrete retaining walls can be constructed along the west side of the roadway to retain cut slopes. The use of concrete retaining walls (instead of rockeries or block walls) may be more favorable where cuts exceed 10 feet in height and where surcharge loads from buildings, driveways, or traffic, may affect cut slopes. Non -gravity type walls (such as CMU walls) will not be adequate to retain the cuts along the roadway and are not recommended. Drainage associated with the cut slope retaining structures and with water on pavements can be directed to catch basins that are installed in the roadway and connected to the local storm drain system. Drainage associated with the fill slope walls on the east side of the roadway should also be tightlined to a storm drain system. Geo Group Northwest, Inc. 1 1 1 1 1 1 1 1 1 1 1 1 A 1 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 32 3.11.2 Driveway Stream Crossing Based on the available information, earthwork for the driveway on Lot 4 is anticipated to require more filling than cutting in order to meet the ECDC requirements for driveway slopes (driveway slopes should not exceed 14 percent except under certain conditions, where slopes of up to 20 percent may be allowed). The proposed driveway is approximately 80 feet long over an elevation gain of approximately 15 feet. In this scenario, Geogrid-reinforced fills and modular block walls can be used to support the roadway in a minimum amount of space and can easily be incorporated into the design for the stream crossing that involves either a box culvert or a backfilled corrugated metal pipe. Another option that could be implemented in construction of the driveway and stream crossing consists of designing a pile -supported structural driveway deck that spans the stream and the portion of the stream buffer that is lower than the design driveway grade. Storm drain and side sewer lines could be attached to the underside of the driveway deck. Post -construction impacts to the stream and stream buffer areas would be significantly reduced, as there would be minimal loss of habitat area. Poor quality subgrade conditions are anticipated in the location of the sewer line trench in the driveway areas. For this reason, we recommend that the pavement section over the trench area consist of a layer of crushed rock at least 18 inches in thickness wrapped with a layer of geotextile fabric (such as Miraf, 140NL or equivalent). The crushed rock and geotextile can be subsequently covered with structural fill where needed to achieve the design driveway subgrade elevation. No upper layer of geotextile fabric is needed if asphalt pavement is placed directly on the crushed rock base. A drainage pipe should be installed at the lowest part of the crushed rock layer. The drain pipe should consist of a 4-inch diameter perforated PVC pipe. The pipe should have a slope sufficient to generate flow and should be connected to a tight line for discharge to an appropriate location (such as a storm drain system). This line should not be tightlined into the wall drain system. Geo Group Northwest, Inc. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 February 25, 2000 G-1061-1 Mr. John Thoresen - Sequoia Ridge Partners Page 33 3.12 Post -Construction Soil Stabilization and Re -vegetation Areas where soils were exposed during construction should be replanted with appropriate native plant species to stabilize the soils. Selected plants should not require significant watering by homeowners. The vegetation should be monitored as it becomes established, and areas where vegetation does not take hold should be evaluated for repeated re -planting or for other methods to stabilize the surficial soils. Mulching and jute netting can be used to help stabilize the surficial soil during the re -vegetation process. The utility easement should also be monitored by the homeowners to ensure that re -vegetation and soil stabilization measures instituted after construction are adequately preventing erosion or sedimentation impacts to downslope areas. The easement should not be re -vegetated with trees, to avoid possible damage to the utilities and to allow access along the length of the easement if repairs are needed. 4 CONSTRUCTION MONITORING AND ADDITIONAL SERVICES We recommend that Geo Group Northwest be retained to perform a geotechnical review of the final completed construction plans for each lot of the proposed development, per ECDC Section 19.05.040. We also recommend that we be retained to conduct geotechnical construction monitoring and observation of the following: • earthwork quality control, • subgrade preparation, • pile installation, • site drainage, • temporary erosion and sedimentation control, • pavement subgrade preparation, • utility trenching and backfilling, and • rockery and retaining wall construction. We also recommend periodic monitoring of the steep west -facing slope during construction for indications of soil movement or other signs of potential instability. Geo Group Northwest, Inc. 1 February 25, 2000 Mr. John Thoresen - Sequoia Ridge Partners ' 5 LIMITATIONS G-1061-1 Page 34 This project has been prepared for the specific application to this site for the exclusive use of i Sequoia Ridge Partners, and its authorized representatives. Reliance on this report by other parties is solely at their own risk. We recommend that this report be included in its entirety in ' the project contract documents for reference during construction. Our findings and recommendations stated herein are based on field observations, our experience i and judgement. The recommendations are our professional opinion derived in a manner consistent with the level of care and skill ordinarily exercised by other members of the profession i currently practicing under similar conditions in this area and within the budget and schedule constraints. No warranty is expressed or implied. In the event that soil conditions are found to ' vary from those anticipated, Geo Group Northwest, Inc. should be notified and the above recommendation should be re-evaluated. L 1 1 f 1 1 We appreciate the opportunity to provide Sequoia Ridge Partners with geotechnical services. Please feel free to contact us if you have any questions regarding this report. Sincerely, Geo Group Northwest, Inc. Keith Johnson Geologist V�Nm C wasy,�,o� G 0 t k 20114 S�9hIAL�� ILVWM 2/ 1W Zoc?z_ i William Chang, P.E. Principal Geo Group Northwest, Inc, 1 REFERENCES City of Edmonds, 1999, Determination of Significance and Request for Comments on Scope of EIS, February 26, 1999. City of Edmonds, 1998, City of Edmonds Environmental Checklist, Sequoia Ridge Short Subdivision, June 12, 1998. DEA, 1998, Drainage Report & Calculations. Sequoia Ridge Subdivision_ City of Edmonds, Washington, David Evans & Associates, Inc., September 25, 1998. GeoEngineers, 1985, Report of Geotechnical Consultation, Property Value Appraisals and Assessments. Meadowdale Landslide Area, Edmonds, Washingion, Geo Engineers, Inc., for City of Edmonds, February 28, 1985. Geo Group Northwest, 1999, Final Limited Scope Environmental Impact Stud , Proposed Sequoia Ridge Short Subdivision, Edmonds, Washington, Geo Group Northwest, Inc., and B- twelve Associates, Inc., August 31, 1999. Minard, 1983, Geologic Map of the Edmonds East and Part of the Edmonds -West uadranles ' Washinglton, Minard, James P., U.S. Geological Survey Miscellaneous Field Studies Map MF- 1541, 1983. ' NCA, 1995, Preliminary Geotechnical Engineering Report, Residential Development Edmonds Washington, Nelson-Couvrette & Associates, Inc., for Mr. John Johnson, March 28, 1995. PIE, 1998, Critical Area Study. Sequoia Ridge, Edmonds, Washington, Pacific International Engineering, P.L.L.C., for David Evans and Associates, Inc., Everett, Washington, July 1998. RLA, 1979,. Final Report, Landslide Hazards Investigation, Meadowdale Area, Edmonds, Washingion, Roger Lowe Associates, Inc., for the City of Edmonds, October 16, 1979. Terra, 1989, Geotechnical Report, Meadowdale Beach, Lots 54 to 57, Edmonds. Washinglon, Terra Associates, Inc., June 6, 1989. Geo Group Northwest, Inc. 1 J 1 1 SCS, 1983, Soil Survey of Snohomish County Area, Washin ton, U.S. Department of Agriculture Soil Conservation Service, 1983. Geo Group Northwest, Inc. 1 1 1 1 1 1 1 1 1 1 1 1 1 FIGURES Geo Group Northwest, Inc. -0 �. l t OE.CN 3 /=a�J1, , s X i Lf P I 3N 3 i 14TNR)w i %r 5 HSNEa 10 Y i i IS TN Y E w Isrw sw s APT tw sr D - w s I)IST fT i ? IIITI aW o X IR09T' ' -Mya t IfHD n fw t 1laTM 9i -. 156TN Si fW 1 aw o, 3 T 3 t Y Y Y ,. fw }��.. r�: a�a..s_ mrx nsw: k - ISIT. IL fw i 1l91 �n fw PROJECT I.T.IS $rfw r I SITEoil 3 D ; i ,r ezwo � '; IaiNOKsw �-�—�___�. '� < avaaW Y '°1 `? Y MEADOWDRLE \•. uuT n Y . 1ba IT 1131 } x T Isar nsW I.T. ST 3 T iT Y; IMTNPLSW aW t RO ^ • a+ I'm 3 n Sw ., '! i a u T — I65TN � % ;G_ •C�44`byo -TH W It sw nsw Y ,�fr MEADOWDALF F F F 6 < (•. 1,,. ~ELEM SCH rrti BEVERLY i _ _,+o F ^ < 9 r aw aT sw •` 1 K ELEM SCH uRTou �.,\ 4 f: MEADOW—.. MIDDLE SCHOOL ItMEADOWDALE ; °G• ry S HIGH SCHOOL € Iam n SwX EMIN ST fW y<r Sar 9w 3 ~ 1 1ST TSW ✓ T IIISTK + € sw r J'x Jw" 4 d 1)mD IINDi ; Y VmDST PR fr fW VmO IT Sw ♦a si sW IiSNO aT aW 4sy »a sr sw i ! 9ND i S' w S4 x V ] ° X ST Sw IISNO P� 1)lRO sr aw ! I 11N0 PL sw o ?r �>arNa)sW iSw= + r •• P £ Ls;Ii. aW ' TKaDT IT sw [i 174TN ET sw ItE. s7 rHOMAs e T ' 1rlTH t ® IS,R ma-5K 1)STH ✓L < n 1)4TN !T o tw ��t:. �t4ay" -';'} ,R "�'�•.i r � 5 aOb NrOo I>arN ns; b YyE5T }fiGO NTY �tK x� r 4 i+o aw Y i Y 3 T Y nrN IT sw ?; T �••^. .rn�. SOUND !t = _ 111TN+ 171TN !T n Sw VIEW Wr DR lr fW • 1))TN r Sw = II C IT sw 1 z n X O°TNrI : verN n sw E s t ; 1 7 ?sr '� i...E s .T I 1 IaarN fr sw 5•' sW X ` N IaOTN aw i ..IsmN . sT a. IfOTH IT IN Ie1 n A.'.... : IUAnaw 't zw Ielsr £ o' I less R Y a' Ie9ND ITS- +k lrmD ST sw ew 5 EulTnfw 1 I�+Dnaw t IraNOR wf srfW le£No T IS ezxo sT ; la)ROn aw y 90N = 00[ wT nsw 4)aD �: Is. sw �, 1e)R dT T Sw by syy a+' k s .F 3 0 0 ! T sw •D ' n sw Y Y I INTN IT a SW a = s �, _� Ie.iN E' •y r =iT o T = a w v..�..w....., 1 { n T' Y I snw 9'i ^ IasTN I sr t Y t5sTw zr + Y + Y 9w {fir IrsiH '' IeSTN xT T IS i ET L ^ IasTNn p • ') fwf IaSTNn ^ IearN n F S s ��i'kr evE"- _ _ LI'b_. r _5_ — "_ _ fw_. -IasIM1 �SQe r -I -a 1{erNnfw IemI R{p .IasrN n sw _ w 1 TM r� aw t k Sam Ft wi wilt IT SIR II7tN {T ,• tam ' t MIR,7t,"zW 1 . ;� .f1N ,.•• I"TH :ST.:Sw r s i I:rtNK 4 K w _ a aT'" T LY�IV ! 4 •; €s ii' t 'SEA VIEW Sir s zs IaerH IeeT11 sw E :t a HEfGHTSF T �: PExxr LN w t 3 Ie9TN n t rH ST SW ELEM SCH- ^ - , e9- n C '• fw 112 sr 3•' Ia9nLn 4 �" t Ie9TN n sw � I N w IsmN n aw ;w = • t9DTiI craw ' 4 � iT 19orN ar aw I M (.- = IfTnn L b13 I91S, aT aw i Y 3 °4 'b 4 Y' ^ a T I90T" 9T SW DALEWAY 190- 19DTN'fT S,ERM„ a 191aT O ;t, 19TfT.. • IbTN /T SW at NEIGHBORHOOD N• T a Sr' f ALE I11lt If eT S Tt 9 IT T sW PAW(.—�. PL aw - O n to r Sw P-1*1193N0 ai it 1�Y eT S(.il OEwl =5a 19t 99 e19SNDR IY>M1 I P' SW ST O Y T t O i ; T 193NOR iw i T 3w 0 3 PNRa w,,. O a = 19fR0 n M Y 19)RD n SW S RD <;; t +)RD I 1 n aw w T sw SCRIBER LAKE > gip! P IurN n f LATH n sw r 3 5 t I ST fw HIGH SCHOOL IMr11 ST SW {w z tuTN 1fT1 n _ Rsa IS w 1 IUTN ■ [ IS J. E D M O NS I = < 9T aw tl N . lYJTN i 9T . ° �' ,9,,,H at urN .it aw Deaaarrr _ _ • = tOt Sit f 197TWN� t 19a`wn T t t: 9TNaraW Y WeTaI>xo T t INTM A. s t ,r♦., w Y't s i.: Ser I� � �. wT ` tt •.. ,-:. sW ,... ., Y r sl r..a�•e' ri - '.� -er_r4 -' VICINITY MAP Group Northwest, Inc. SEQUOIA RIDGE SHORT SUBDIVISION Geotechnical Engineers, Geologists, & 160XX - 72ND AVENUE WEST Environmental Scientists EDMONDS, WASHINGTON SCALE: 1" = 2000' DATE: 6/14/99 MADE: KJ CHKD: WC JOB NO: G-1061 PLATE 1 X O 145.59 A I TOP 151.15 LEGEND CATCH I A BASIN TOP 154.78 TOP 167.16 Exploratory Soil Boring Drilled by Geo Group I.E.CP 168.81 Northwest, Inc. (Approximate Location) r� ,,• r SS � e-1 Hand -Auger Soil Boring by Nelson-Couvrette jgAssoicates, Inc. (Approximate Location) �. TOP 171.90 NC-1 CAT H BASIN TOP 171.90 WATER MANHOLE 2 EAU BUFFER (PRV) SS MANHOLE A ti SS TOP 200.74 1 5,31 I I IE 192.09-80N 1 AT S IE 192.04-8"E 2 4 , + TOP 197.71 IE 191.94-8"W 15 ` �t�, ' CATCH BSI 0 I \ \. r S TOP 202.08 2tQ • I fy EXISTING HYDRANT 17 co�' . 200, ,� , ko p�,T ai N y r ': B-4 ' J�' DP2f X �s >` \y . SS Fq CATCH BA Y A I •jr6 X �gZ.222, SF/ DP ; 26 �,ti' E►1 \ ti ` ` 00, TOP 215.4 C8•• TYPE. 1 ,'. 255' Afo \ i `.J�•4; STREAM .AND ^�:. °t,'•�"i .\ /Ira63 2: WETLAND BOUNDARY 52,248 fr � 7 i •,�T ",• �.. .v:Ll•_;1'il,n. \ ;i<I; .� ,ail. ''•�''t I ? v S? DRAWA EMEKToFOR o \ IDE 'SEWER \ DP 6 �51,222 SF', l'a+" N , •�g,P/ \� ti / l _..., ,... Ri da — t P . (• �) 5>•r•;;� � �1�. � W. 011— TER � ,o•�: , .• `• � •, ;�;t 1 BSMf�254 Y CB ��TYpG E� I sa y:: ..: �\ \ .: ,T.A Yet'`.::. `• w, ., ,`pI IV / / ;, 1/ y \ •� NC-4 �O•. i. . ;t�F� ; ' •. y ; «("'iiil/l,, / `46,891u,SF�y`..•Y- ;?,:,m. �::��, r•,. ISE AL) i::B;Z�:t LLIJ Z tESµ' \ \ IIr• r- 1°DA Uj Z 1489'38'04• TOP OF BANK`' \ ?s NC-1 I 1 i l: G JOHN L JOHNSON `\. L` HDU C / CY LEGEND �' ` '• BUTTER REDUCTION EDGE OFMW �` •1 .\ AREA=2298 SF 00000 ROCKERY ASPHALT % BUFFER ADDITION/COMPENSATION !7S AREA=5750 SF x-- K FENCE POTENTIAL STREAM h BUFFER O SANITARY SEWER MANHOLE LOSS MITIGATION AREA-12B3 SF A FIRE HYDRANT TOP OF 0 CATCH BASIN SS SANITARY SEWER LINE BANK \ ``ti `•, D4 WATER VALVE _OP_ OVERHEAD POWER LINE w GAS VALVE SD STORM DRAIN LINE UTILITY POLE W/ GUY WIRE W WATER LINE TELEPHONE CLOSURE A EDGE OF ASPHALT 25' STREAM BUFFER O. -- \ j \\DRIVWAY iY 4 DP 26XRP43 2SDP <26 \;`, ,F/ �E , N',1'� ' STREAM AND \ WETLAND BQ1-J1`16ARY 2�8 SF l ,. 51,222 SF ,DPI ..., i �O 46,891 SF . I LINE OF b BAD , POOTFRINY M 24' OVERNANb t t t \ %}� I �� b 9`10 � V1 80.19'4.7. / A ' w NC-S NC-3 W I I r (' ` \ 1 \ , I i r _ \ '�'--Sete,.cK�` � I .IT-0• j / �-, ��` �. 34,052 SF I • `� MAC 00\ LEGEND � \ ' \ ly \ EXPLORATORYSOIL BORING BY GEO GROUP ' ` �• NORTHWEST (APPROXIMATE LOCATION) J ' g-t �I �b EXPLORATORY HAND AUGER BORING BY NELSON- COUVRETTE & ASSOC. (APPROXIMATE LOCATION) NC-1 „mot SUBSURFACE PROFILE LINE A At (l,�� Group Northwest, Inc. 0 50 100 SCALE: I inch = 50 feet DEVELOPMENT PLAN - Geotechnical Engineers, Geologists, & Environmental Scientists SCALE: 1" = 50' 1 DATE: 2/17/00 1 MADE: KJ I CHKD SEQUOIA RIDGE SHORT SUBDIVISION EDMONDS, WASHINGTON WC I JOB NO: G-1061-1 I PLATE 3 SOUTH LAI 300 280 F W W 260 O F W w 240 220 200 PROPOSED RESIDENCE B-1 1401 —'— [221 [131 -- t321. LOT I I LOT 2 PROPOSED ROCKERY i [39] SAND (SP-SM) -1641 [50+1 i I NORTH i LOT 2 r LOT 3 i i PROPOSED RESIDENCE NC-5 t I $-2 PROPOSED DRIVEWAY [50+1 S 4] SM SAND (SP) W/GRAVEL ( ) 161 . 4 [611 [50+J i SAND (SP) ? LEGEND B-1 EXPLORATORY SOIL BORING WITH 1321 SAMPLING LOCATIONS AND SOIL PENETRATION TEST RESULT NC-5 HAND AUGER BORING APPROXIMATE OR INFERRED GEOLOGIC CONTACT GROUNDWATER TABLE PROPOSED RESIDENCE ELEVATION TO BE DETERMINED B-3 - 260 [151 =.e..... 1 [251 [s11 1291 240 [601 ' 1791 ? — — SZ- 06+1 _ ----- � +- 220 ptiff I i 1 SUBSURFACE PROFILE A -A' 0 20 40 ffln'Group Northwest, Inc. SCALE: 1 inch = 20 feet Geotechnical Engineers, Geologists, & SEQUOIA RIDGE SHORT SUBDIVISION Environmental Scientists EDMONDS, WASHINGTON SCALE: V = 20' DATE: 2/17/00 MADE: KJ CHKD: WC JOB NO: G-1061-1 PLATE 5 I WEST i EAST 300 BUILDING SETBACK PROPOSED RESIDENCE ( AREA TOP OF BANK 1 1 1 t B-2 280 SILTY SAND 16] ] [4(4 W/GRAVEL (SM) [611 01 [50+] w 260 z zj J SAND (SP) o � SAND (SP) w 240 - -- - . 1 SEEPAGE ELEVATION - (APPROXIMATE)- 220 200 SILT, SILTY SAND, AND SAND (ML/SM/SP) 0 20 40 SCALE: 1 inch = 20 feet Bf LEGEND f B-I EXPLORATORY SOIL BORING WITH [32J SAMPLING LOCATIONS AND PROPOSED ROCKERY SOIL PENETRATION TEST RESULT ? APPROXIMATE OR INFERRED PROPOSED DRIVEWAY GEOLOGIC CONTACT II 240 Group Northwest, Inc. Geotechnical Engineers, Geologists, & Environmental Scientists SCALE: V = 20' DATE: 2/17/00 1 MADE: 220 200 SUBSURFACE PROFILE B-B' SEQUOIA RIDGE SHORT SUBDIVISION EDMONDS, WASHINGTON KJ ( CHKD: WC I JOB NO: G-1061-1 I PLATE 6 SOUTH C PROPOSED RESIDENCE 260 B-3 t [2] [15] [25] [51] [29] 240 [46] [60] [79] -[- - w 220- O d 200-- W 180 160 ELEVATION TO BE DETERMINED LEGEND SAND (SP) LOT 3 1 LOT 4 l � I I 9— SILT, SILTY SAND, AND SAND (ML/SM/SP) B-3 EXPLORATORY SOIL BORING WITH SOIL [28] PENETRATION TEST RESULTS (BLOWS PER 12 INCHES OF PENETRATION) APPROXIMATE OR INFERRED GEOLOGIC CONTACT y GROUNDWATER ELEVATION OBSERVED DURING DRILLING (MAY 1999) ELEVATION TO BE DETERMINED SILT, SILTY SAND, AND SAND (ML/SM/SP) PROPOSED RESIDENCE B-4 [41 [8} [16] [11] _ [28] [39] [44] [48] [50+] NORTH; C' r tr1 C PROPERTY LINE 021 H PROPOSED RETAINING WALL WITH 220 GEOGRID REINFORCEMENT PROPOSED DRIVEWAY I 200 STREAM - --- .180 160 0 20 40 SUBSURFACE PROFILE C-C' SCALE: 1 inch = 20 feet �l, Group Northwest, Inc. i �— Geotechnical Engineers. Geologists, 8. SEQUOIA RIDGE SHORT SUBDIVISION Environmental Scientists ( EDMONDS, WASHINGTON SCALE: 1" = 20' DATE: 2/25/00 MADE: KJ I CHKD: WC JOB NO: G-1061-1 I PLATE 6A i -let 1-144 158TH ''3 157cV ! 1_142 1-140 15730 l5732 , v 1-150 SKID T 'PIEZO 1-t6s 1-2 i �� 1_141 1TA�7 732I W 1S914 IJBDD L78QB 1 1=4 - 49 f Q 1J809 1.S912 3 1-i48 tJ82� t-t2a 15M 1-7 1J8I8 15W4 I_wff O 1-127 1-147 1� 15"LI46 lSB2>j L'22S L7828 1-31 -3 ` l_29 ! o... fi tZ-TL 15904 _ 15911 II_*l07 1191p2 159/0 1-e7• 1591 ^ -04 1-19 Z v2 t59D2 ! 39GG l i-26 -76 N 5917 1178 lSSt79 = PtEm IEZ 15920 � -19 1/4 15915 }- t_ 1-79 1-77 � � 16" 1-79 t_ d •o.n..rc..w a..Jci_ I 1-113 a � 69V 13920 1-74 -2J1-22 t-21 1-Zsl 160TH T SW J6Ui2 1-33 16Q0 2 1-e1 %L 1-n 161Z1 11931 16123 I6008 1-U6 69J0 6a�D \ 1-BS 1- 6970 , 1-t12 16024 16oD 2I( -84 1-87 160tg !60! -36 1 1 6916 6010 ! l6119 16115 16020 a 9b0 3 1 T r-. 1171 1-71 Q !61 eSpD I6M 1451 � �8. to 1410:9 '9 I 1-134 161" lal GRIMM v ER 1-170 1-78 1 6919 6W • rrsr� ` 12 ^ 162D9 6912 t-f32 6I0 16J0 t I-169 1' 6gga 6 S T 7-43o t-9a ` 1_ l61G0 -6 l6215 1-133 6804 l6J13 ' 6!! -i36 . l61J1 6 6121 Q I6122 lZ f'VC- 7 i I !ells is 1-� t-173 D WATER 1 397 f 1-8"9 -44 iNTERCEPTaR SYSTEM ' t-90 1-as �' 1�02 W 16209 l6216 c� C P 20 >a4 16209 Q 4 J621! 1-16i -101 Q°L7V SPACE 1-41 Q 1-30 1_34 ' 1-53 692J 162IJ 16220 1'� v d 20 160-9 6BD1 16310 _9 -52 6923� 16Q3B 10 162P3 1-100 I 6eV5 t-tt2 163PD 16236 622� 11-33 1-38 1-163 ` 16225 69eJ ' l622L' t 1-99 16330 t61/! A t-31 l6cW ly t-1st! /6317 I 69l9 6908 C 1-104 Nt- 1-99 69IS P 16719 16315 l6720 1 6' -f77 $04 16719 6909 L t 31 _9S 6901 0 -teo I6�29 '^ ', 710! l6727 16722 '6 . 3 1-54 1-30 1-47 16J2J 1-% 1-Js. i77 1-s4 I i Reference: Nelson-Couvrette & Associates, Inc., 1995. VICINITY DRAINAGE MAP Group Northwest, Inc. ; :- Geotechnical Engineers, Geologists, & 1l SEQUOIA RIDGE SHORT SUBDIVISION Environmental Scientists 1 EDMONDS, WASHINGTON SCALE: 1" = 250' (+/-) DATE: 2/17/00 MADE: KJ CHKD: WC JOB NO: G-1061-1 PLATE 3A Relative Impermeable Compacted Backfll Free draining material (Washed rock or Crushed rock) Geotextile (Miraft 140 NL, or equivalent) 4 or 6 inch diameter slotted or perforated PVC pipe Slope to drain COMPACTED ONSITE BACKFILL MATERL4L (IF USABLE) Basement Wall Vertical Drain Mat (Miradrain 6000 or equivalent) A MOT.ING I NOT TO SCALE NOTES: 1.) Do not replace rigid PVC pipe with flexible corrugated plastic pipe. 2.) Perforated or slotted PVC pipe should be tight jointed and laid with perforations or slots down, with positive gradient to discharge. 3.) Do not connect roof downspout drains into the footing drain lines. 4.) Backfill should be compacted to 90% of maximum dry density based on Modified Proctor. The top one foot should be compacted to 95% of maximum dry density if backfill is to support sidewalks, driveway, etc. �1 Group Northwest, Inc. Geotechnical Engineers, Geologists, & Environmental scientists TYPICAL BASEMENT WALL BACKFILL AND DRAINAGE SEQUOIA RIDGE SHORT SUBDIVISION EDMONDS, WASHINGTON SCALE NONE 1 DATE 2/23/007 - 1 MADE KJ __ I CHKD WC I JOB NO. G-1061-1 I PLATE 8 Relatively impermeable, compacted backfill Geotextile filter fabric, (Mirafr 140 NS, or equivalent) Free draining material, (Washed crushed rock or drain rock) Minimum 4-inch diameter slotted or perforated PVC pipe with positive gradient to discharge Slope to drain NOT TO SCALE NOTES: 1.) Do not replace rigid PVC pipe with flexible corrugated plastic pipe. 2.) Perforated or slotted PVC pipe should be tight jointed and laid with perforations or slots down, with positive gradient to discharge. 3.) Do not connect roof downspout drains into the footing drain lines. 4.) Backfill should be compacted to 90% of maximum dry density based on Modified Proctor. The top 12 inches shall be compacted to 95% of maximum dry density if backfill is to support sidewalks, driveway, etc. FOOTING TYPICAL FOOTING DRAIN Group Northwest, Inc. Geotecnnical Engineers, Geologists, & SEQUOIA RIDGE SHORT SUBDIVISION Environmental Scientists EDMONDS, WASHINGTON SCALE NONE DATE 2/23/00 MADE KJ CHKD WC TiOBNO. G-1061-1 PLATE 9 I I I I APPENDIX A BORING LOGS Geo Group Northwest, Inc. LEGEND OF SOIL CLASSIFICATION AND PENETRATION TEST UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) MAJOR DIVISION GROUP TYPICAL DESCRIPTION LABORATORY CLASSIFICATION CRITERIA SYMBOL CLEAN GRAVELS GRAVELS (little or no COARSE. (More Than Half fines) GRAINED SOILS Coarse Grains Larger Than No. 4 Sieve) DIRTY GRAVELS (with some fines) SANDS CLEAN SANDS More Than Half by Weight Larger (More Than Half Coarse Grains Smaller Than No. 0ittie or no fines) Than No. 200 4 Sieve) Sieve DIRTY SANDS (with some fines) SILTS Liquid Limit (Below A -Line on < 50% Plasticity Chart, Liquid Limit FINE-GRAINED Negligible SOILS Organic) > 50% CLAYS Liquid Limit (Above A -Line on < 30% Plasticity Chart Liquid Limit Negligible Organic) > 50% More Than Half by Weight Larger Than No. 200 Sieve ORGANIC SILTS & CLAYS (Below A -Line on Liquid Limit < 50% Plasticity Chart) Liq�Llmit HIGHLY ORGANIC SOILS WELL GRADED GRAVELS, GRAVEL -SAND Cu = (D60 / D10) greater than 4 GW MIXTURE, LITTLE OR NO FINES DETERMINE Cc = (D302) / (D10 " D60) between 1 and 3 PERCENTAGES OF POORLY GRADED GRAVELS, AND GRAVEL -SAND GRAVEL AND SAND GP MIXTURES LITTLE OR NO FINES FROM GRAIN SIZE NOT MEETINGABOVE REQUIREMENTS DISTRIBUTION CURVE ATTERBERG LIMITS BELOW GM SILTY GRAVELS, GRAVEL -SAND -SILT MIXTURES "A" LINE. CONTENT OF FINES EXCEEDS 12% or P.I. LESS THAN 4 CLAYEY GRAVELS, GRAVEL -SAND -CLAY ATTERSERG LIMITS ABOVE GC MIXTURES COARSE GRAINED "A" LINE SOILS ARE CLASSIFIED AS or P.I. MORE THAN 7 SW WELL GRADED SANDS, GRAVELLY SANDS, FOLLOWS: Cu = (1380 / D10) greater than 6 LITTLE OR NO FINES < 5% Fine Grained: Cc = (D30') / (D10 • D60) between 1 and 3 SP POORLY GRADED SANDS, GRAVELLY SANDS, NOT MEETING ABOVE REQUIREMENTS LITTLE OR NO FINES GW, GP, SW, SP 12% > 12% Fine Grained: ATTERBERG LIMITS BELOW SM SILTY SANDS, SAND -SILT MIXTURES "A" LINE GC, SM, SC 5 to 12% Fine CONTENT OF FINES EXCEEDS 12% with P.I. LESS THAN 4 ATTERBERG LIMITS ABOVE SC CLAYEY SANDS, SAND -CLAY MIXTURES Grained: use dual "A" LINE symbols with P.I. MORE THAN 7 ML MH CL CH OL OH Pt INORGANIC SILTS, ROCK FLOUR, SANDY SILTS OF SLIGHT PLASTICITY 80 INORGANIC SILTS, MICACEOUS OR 50 DIATOMACEOUS, FINE SANDY OR SILTY SOIL INORGANIC CLAYS OF LOW PLASTICITY, 40 GRAVELLY, SANDY, OR SILTY CLAYS, CLEAN a CLAYS Z 30 - INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS V �ORGANIC 20- SILTS AND ORGANIC SILTY CLAYS OF a LOW PLASTICITY 10- 7' ORGANIC CLAYS OF HIGH PLASTICITY 4' 0 LASTICITY CHART LNO. 40 SIEVE all ENE4 I ,----,----- 0 10 20 30 40 50 80 70 80 90 100 110 PEAT AND OTHER HIGHLY ORGANIC SOILS LIQUID LIMIT (%) SOIL PARTICLE SIZE GENERAL GUIDANCE OF SOIL ENGINEERING PROPERTIES FROM STANDARD PENETRATION TEST (SPT) U.S. STANDARD SIEVE FRACTION Passing Retained SANDY SOILS SILTY & CLAYEY SOILS SizSize) Size Sieve Sieve Blow Relative Friction Blow Unconfined Size Counts Density Angle Description Counts Strength Description SILT ICLAY #200 0.075 N % io, degree N qu,tsf SAND 0-4 0 -15 Very Loose < 2 < 0.25 Very soft FINE #40 0.425 #200 0.075 4 -10 15.35 26 - 30 Loose 2-4 0.25 - 0.50 Soft MEDIUM #10 2.00 #40 0.425 10.30 35 - 65 28 - 35 Medium Dense 4.8 0.50 -1.00 Medium Stiff COARSE #4 4.75 #10 2.00 30-50 > 50 65 - 85 85 -100 $5.42 38 - 46 Dense Very Dense 8.15 15 - 30 1.00.2.00 200 - 4.00 Stiff Very Stiff GRAVEL FINE 19 #4 4.75 1-30 > 4.00 Hard COARSE 76 19 COBBLES 78 mm to 203 mm • Group Northwest, Inc. BOULDERS >203mm Geotechnical Engineers, Geologists, & ErvlronmentalScientists ROCK > 78 mm FRAGMENTS 13240 NE 20th Street, Suite 12 Bellevue, WA 98005 Phone (425) 849-8757 Fax (41M 849-8758 P LATE Al ROCK 4.76 cubic meter In volume r BORING NO. B-1 Page 1 of 1 Logged By: KJ Date Drilled: 5/18/99 Surface Elev. 310 feet +/- Sample Blow Water Depth USCS Description Count per Content Other Tests & ft. Code 6-inches % Comments Type No. Lawn surface Sl 9,20,20 2.2 Blow counts affected Sp_ (N=40) by tree root near SM SAND to SILTY SAND, damp, medium dense, fine grained sand 9.0 surface. 10-15%fines, little subrounded gravel, dark brown (becomes gray S2 11,11,11 SP- at 2 feet). (N=2222) 5 SM -- S3 21,10,3 7.3 Sp SAND, damp, medium dense, fine grained sand, grayish brown. (N=13) SP As above, dense, fine to medium grained sand, trace gravel, S4 10,14,18 8.0 occasional lenses of well graded silty sand. (N=32) 10 Sp As above, brownish gray, trace coarse sand and gravel. S5 13,19,20 (N=39) 7 8 15 Sp As above, very dense, fine grained sand. S6 21,30,34 8.7 (N=64) 20 SP As above. = S7 29,50/3" (N=50+) 7.4 25 Sp As above. = 32,50 S8 (N=50+) 6.2 30 SP As above, very fine to fine grained, 1" thick silty sand lens in sample. Sq 23,28,50 6.4 (N=78) Bottom of boring: 31.5 feet. 35 Drilling Method: Hollow -stem auger (portable). Sampling Method: 2-inch-O.D. standard penetration sampler driven using a 140 lb. hammer with a 30-inch drop. No groundwater encountered during drilling. LEGEND: = 2" O.D. Split -Spoon Sampler GROUNDWATER seal T 3" O.D. Shelby -Tube Sampler OBSERVATION WELL: measured water level 3" O.D. California Sampler well tip (screen) BORING LOG Group Northwest, Inc. PROPOSED RESIDENTIAL DEVELOPMENT �� SEQUOIA RIDGE SHORT SUBDIVISION Geotechnical Engineers, Geologists, & EDMONDS, WASHINGTON Environmental Scientists JOB NO. G-1061 DATE 5/20/99I PLATE A2 4 1 1 1 1 BORING NO. B-2 Page 1 of 1 Logged By: KJ Date Drilled: 5/18/99 Surface Elev. 285 feet +/- Sample Blow Water Depth USCS Description Count per Content Other Tests & ft. Code 6-inches % Comments Type No. SM Ivy landscaping, SILTY SAND, brown, damp, loose, 10-15% S1 3,2,2 13.6 Wet cuttings gravel. (N=4) encountered at about SM SILTY SAND, damp, medium dense, fine grained sand, 10-15% 3 feet during drilling fines_ little subrounded gravel_ gray. SZ 3,1,5 (N�) 11.7 (suspected perched 5 water zone SM SILTY SAND with gravel, damp, dense, fine grained sand, S3 14,15,25 9.5 encountered). ) olive gray (GLACIAL TILL). (N=40) SM As above, very dense. S4 39,26,35 9.1 (N=61) 10 SM As above, poor sampler penetration due to rock. = S5 32,50 (N=so+) Drilling refusal at 13 feet. 15 Bottom of boring: 13 feet. Drilling Method: Hollow -stem auger (portable). Sampling Method: 2-inch-O.D, standard penetration sampler driven using a 140 lb. hammer with a 30-inch drop. Minor groundwater seepage noted around 2 feet during drilling. 20 25 30 35 LEGEND: I 2" O.D. Split -Spoon Sampler GROUNDWATER seal 3" O.D. Shelby -Tube Sampler OBSERVATION WELL: measured water level 3" O.D. California Sampler EDwell tip (screen) BORING LOG • Group Northwest, Inc. PROPOSED RESIDENTIAL DEVELOPMENT SEQUOIA RIDGE SHORT SUBDIVISION Geotechnical Engineers, Geologists, & EDMONDS, WASHINGTON Environmental Scieriiists JOB NO. G-1061 DATE 5/20/99 IPLATE A3 1 1 1 1 BORING NO. B-3 Page 1 of 1 Logged By: KJ Date Drilled: 5/18/99 Surface Elev. 255 feet +/- Sample Blow Water Depth USCS Description Count per Content Other Tests & ft. Code 6-inches % Comments Type No. Sp Ivy surface. SAND, dark yellowish brown, damp, fine grained S1 1,1,1 16.6 _ sand -very loose. _ _ _ _ (N=2) SM SILTY SAND, moist, medium dense, fine grained sand with 5,8,7 11.2 gravel, brown. I S2 (N=15) 5 _ — — — S3 27,12,13 9.3 Sample at 5 feet Sp ___-- SAND, damp, medium dense, fine grained sand, brown. � (N=25) affected by water added to hole. SP As above, very dense, fine to medium grained sand, grayish S4 15,25,26 6.6 brown. (N=51) 10 Sp As above, moist, medium dense, silty sand lense at bottom of S5 9,12,17 29 ) 11.5 sample, brownish gray. 15 Sp As above, damp, dense, fine grained sand, gray. S6 12,17,29 12.9 (N=46) 20 Sp As above, very dense, moist. S7 19,27,33(N=60) 8.0 25 Sp As above, damp. S8 25,34,45 6.3 (N=79) 30 SP As above, wet, very fine to fine grained sand, 5%fines. = 28,50 Groundwater S9 (N=50+) 24.5 ecountered at 29 to 30 feet during Bottom of boring: 31 feet. drilling. ` 35 Drilling Method: Hollow -stem auger (portable). Sampling Method: 2-inch-O.D. standard penetration sampler driven using a 140 lb. hammer with a 30-inch drop. Groundwater encountered at approximately 29 to 30 feet during drilling. LEGEND: = 2" O.D. Split -Spoon Sampler GROUNDWATER seal T 3" O.D. Shelby -Tube Sampler OBSERVATION WELL: measured water level 3" O.D. California Sampler well tip (screen) _ BORING LOG Group Northwest, Inc. PROPOSED RESIDENTIAL DEVELOPMENT SEQUOIA RIDGE SHORT SUBDIVISION Geotechnical Engineers, Geologists, & EDMONDS, WASHINGTON Environmental Scientists JOB NO. G-1061 DATE 5/20/99 PLATE A4 1 1 Ll 61, BORING NO. B-4 Page 1 of 1 Logged By: KJ Date Drilled: 5/19/99 Surface Elev. 215 feet +/- Sample Blow Water Depth USCS Description Count per Content Other Tests & ft. Code 6-inches % Comments Tye No. Sp Forest duff surface. SILTY SAND, damp, loose, fine grained S1 1,1,3 32.1 --- sand, brown. ------------------------------------ (N=4) SP/ SAND and SILTY SAND, moist, loose, fine grained sand, 5,4,4 14.1 SM mottled brown and gray. = S2 (N=8) 5 ----------------------------- SM/ ---------- SILTY SAND and SILT, moist to wet, medium dense, gray and S3 347 33.3 Possible thin perched brown with reddish oxide staining, silty sand is micaceous, (N=11) water zone at about 6 ML occasional fine sand layers (without fines). feet based on ML SILT, damp to moist, stiff, reddish oxide staining, olive gray. S4 8,7,9 (N=16) 31.6 observed wet cuttings. 10 ly it As above, damp, very stiff, no oxide staining, some very thin S5 7,12,16 (N=28) 34.3 vertical fine sand laminae and occasional powdery horizontal laminae, occasional wet fine sand lenses 1 to 2"'thick. 15 S6 15,17,22 23.7 Sp SAND, damp, dense, 10 15% fines, very fine to fine grained = (N=39) SM 20 --------------------------------------- SM/ SILTY SAND and SILT, dense, very fine sand is wet, trace mica S7 1417) 7 17,,2 32.5 ML and fines, silt is damp and laminated to thinly bedded, gray. 25 --------------------------------------- SM SILTY SAND, wet, dense, very fine grained sand, occasional silt S8 17,23,25 25.6 -- lenses a -- - ----------------------------- (N=48) 30 SM/ SILTY SAND and SILT, very dense, sand is very fine to fine ML grained and wet, silt is damp, gray, gravel clast in sand lens. = 35,50/5" S9 (N=50+) 33.8 Bottom of boring: 31 feet. Drilling Method: Hollow -stem auger (portable). 35 Sampling Method: 2-inch-O.D. standard penetration sampler driven using a 140 lb. hammer with a 30-inch drop. Suspected thin perched groundwater zone encountered at approximately 6 feet,during drilling; most sand layers observed to be wet, but no flowing water. LEGEND: = 2" O.D. Split -Spoon Sampler GROUNDWATER eal T 3" O.D. Shelby -Tube Sampler OBSERVATION WELL: 1, measured water level 3" O.D. California Sampler well tip (screen) BORING LOG PROPOSED RESIDENTIAL DEVELOPMENT Group Northwest, Inc. SEQUOIA RIDGE SHORT SUBDIVISION Geote nrt Engineers, Geologists, & EDMONDS, WASHINGTON Environmental Scientists E JOB NO. G-1061 I DATE 5/20/99 IPLATE AS aimjm mmu�L� i.p.i Sim_ ; _ lm a Lim Kim a..o� � _a_t _�. LAMA -RAMm- N r „1 I 1 tl r�V=Z 06 _ _ -ram♦ + , �/ f r �� 1 � J 7�" 1 �UNITCf/ UNIT $/�'/o,do UNIT A ` \`� '(,�'','. , ,' ! /UNIT Dr( I fJ ► / Jf t 1 f I / 3 ', ,, / / UNIT I . I ; . I /r / ! / 'I �� Fii1-t / ri;/ i !� '� ifr/;/II/� � �� // �//i Jr f�a0 �• � , . �� // ,/,! // / / J ,/�. •' �� ' / I / 'ram i UNIT P dlu i / !//! ♦ ♦ / // i /,/ + I/ /1 ' ; � ` Imo, �` jyca ' ♦ UNITCs''/ '' 'i ///,/,J!// / f I t( t ``•l i �r 0 ` /II/ I/ , � , � , / r, r � f � � •y LEGEND ♦ HA S . I , , , , r , , f ( , • �; NUMBER AND APPROXIMATE LOCATION OF HAND AUGERS PROPOSED 72nd AVENUE WEST _ _ __._�. .. ___ .._ ..� '•--') c / 11NIY A LETTERING SYSTEM BY NCA FOR DESCRIPTIVE PURPOSES f PLAN CREATED FROM UNTITLED AND UNDATED PLAN N ED TO US BY LOVELL-SAUERLAND 6 ASSOCIATES, INC. R I o so too JOHNSON FIGURE NEL ON•COL/YAETTS 6 ASSOCIATES, iNC 2 _ oon+u+e�c awnuw�rwi Emit n FILENC. DATE � L SO' c 145995 MARCH 1995 j SOIL. CLASSIFICATION SYSTEM GROUP MAJOR DIVISIONS SYMBa. GROUP NAME COARSE GRAVEL CLEAN GRAVEL GW . WELL -GRADED GRAVEL, FINE TO COARSE GRAVEL GRAINED GRAVEL GP POORLY -GRADED GRAVEL SOILS MOfi n" 50 OP COMM FPACnO RETAff,� ON WITH FINES GM SILTY GRAVEL N064MW GC CLAYEY GRAVEL ft-fNMM ON SAND CLEAN SAND SW ; WELL -GRADED SAND, FINE TO COARSE SAND No. ]00 SWA SP POORLY -GRADED SAND M0M1WWW%OFC0AR6H FRACNaTs� SAND SM SILTY SAND WITH FINES SC `. CLAYEY SAND FINE SILT AND CLAY INORGANIC ML SILT GRAINED =WUMIT MWIN w" CL CLAY ORGANIC OL ORGANIC SILT, ORGANIC CLAY SOILS SILT AND CLAY INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT MOMiwwW9►PA56Es tlotuOWrOT30%0RMORE CH CLAY OFHIGH PLASTICTIY,FAT CLAY HM 2W S"E ORGANIC OH: ORGANIC CLAY, ORGANIC SILT } HIGHLY ORGANIC SOILS _77 PT PEAT NOTES: SOIL MOISTURE MODIFIERS 1) Field classification Is based on Dry - Absence of moisture, dusty. dry visual examination of soil In general to the touch accordance with ASTM D 24M83. Moist - Damp, but no visible water 2) Soil classification using laboratory tests Is based on ASTM D 2487-83. Wet - Visible free water or saturated, usually soil is obtained from 3) Descriptions of soil density or below water table consttency are based on s interpretation of blowcount data, visual appearance, of soils, and/or J r� test data. ' i NELSON-COUVRETTE & ASSOCIATES, INC. SOIL CLASSIFICATION SYSTEM C"LALIM GEOTBCHWCAL ENGINEERS, GEOLOGISTS AND-WRONMONTAL &WIMSTS .FIGURE 3 06/30/1998 .09:29 4254812510 NELSON-COUVRETTE PAGE 17 LOG OF EXPLORATION DEPTH USC SOIL DESCRIPTION 0.0 - 0.4 BRANCHES. STICKS AND DUFF (VERY LOOSE, MOIST) 0.4-11 SP49A BROWN FINE TO MEDIUM SAND WITH SILT, TRACE ROOTS AND GRAVEL (LOOSE TO MEDIUM DENSE. MOIST) 1.7-2.3 SP BROWN MEDIUM SAND WITH GRAVEL SCATTERED COBBLES AND TRACE SILT (LOOSE TO MEDIUM DENSE, MOIST) (Qu) SAMPLES WERE COLLECTED AT 1.2 -1.7 AND 1.9 - 23 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 23 FEET ON UM HAND AUGER TWO 0.0-2o sP LIGHT BROWN MEDIUM SAND WITH TRACE SILT AND ROOTS (LOOSE TO MEDIUM DENSE, MOIST) 20 - 3.5 SP TAN -GRAY MEDIUM SAND WITH TRACE SILT (MEDIUM DENSE. MOIST) (Qe) SAMPLES WERE COLLECTED AT 1.1-1.8 AND 2S - 3.2 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 3.5 FEET ON 318AB6 HAND AUGER THREE 0.0-20 SP LIGHT BROWN MEDIUM SAND WITH TRACE GRAVEL AND SILT (LOOSE, DAMP TO MOIST) 20-3.0 SP TAN -GRAY MEDIUM SAND WITH TRACE GRAVEL AND SILT (LOOSE TO MEDIUM DENSE GRADES TO MEDIUM DENSE. MOIST) (Ce) SAMPLES WERE COLLECTED AT 1.5 - 20 AND 25 - 2.9 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT &0 FEET ON 3NM HAND AUGER FOUR 0.0 - 0.2 DUFF 0.2 - 0.6 SP LIGHT BROWN MEDIUM SANG WITH TRACE SILT (VERY LOOSE, DRY TO MOIST) (SLOPE WASH) 0.0-1.2 ML DARK BROWN TO BLACK ORWWIC SANDY SILT (SOFT, DAMP TO MOIST) (BURIED TOPSOIL) 1.2-4.5 SP LIGHT BROWN MEDIUM SAND WITH TRACE GRAVEL AND SILT (LOOSE TO MEDIUM DENSE GRADES TO MEDIUM DENSE, MOIST) (t,>le) SAMPLES WERE COLLECTED AT 0.6 -1.0 AND 4.0 - 4.6 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED HAND AUGER WAS COMPLETED AT 4.5 FEET ON 3MM H WD AUGER FIVE 0.0 - 0.6 DUFF 0.6-2.5 sM LIGHT GRAY RUST 13ROWN MOTTLED SILTY FINE TO MEDIUM SAND WITH GRAVEL AND SCATTERED COBBLES (MEDIUM DENSE, MOIST) (Qs) SAMPLES WERE COLLECTED "AT 1.3 -1.8 AND 2.0 - 24 FEET GROUND WATER WAS NOT ENCOUNTERED. HAND AUGER WAS COMPLETED AT 25 FEET ON 3A M NELSON-COWRETTE a ASSOCL4TES, INC. FILE NO.145W FIGURE 4 APPENDIX B i ROCKERY CONSTRUCTION GUIDELINES J 1 Geo Group Northwest, Inc. i ,SRC Association of Rockery Contractors i ASSOCIATION OF ROCKERY CONTRACTORS I STANDARD ROCKERY CONSTRUCTION GUIDELINES 1.01 Introduction 1.01.1 Historical Background: These standard rockery construction guidelines have been developed in an effort Sto provide a more stringent degree of control on rockery materials and construction methodology in the Pa:ific Northwest. They have been assembled from numerous other standards presently in use in the .area, from expertise provided by local geotechnical engineers, and from the wide experience of the members of the Association of Rockery Contractors (ARC). 1.01.2 Goal:. The primary goals of this. document are to standardize the methods of construction, and to provide a warranty for the materials used in construction and the workmanship employed in construction. This standard has also been developed in a manner that makes it, to the best of ARC's knowledge, more stringent than the other Stan- dards presently in use by local municipalities. 2.01 Materials: 2.01.1 Rock Quality: All rock shall be sound, un- weathered, weathering resistant, angular ledge rock. The longest, dimension of any individual rock should not .exceed three times its shortest dimension. Acceptability of rock will be determined by laboratory tests as hereinafter specified, geologic examination and historical usage records. i All rock delivered to and incorporated in the project ' shall meet the following minimum specifications: a. Absorption, (Corps of Engineers CRD-C-107) Not more than 3.0% b. Accelerated Expansion (15 days) (CRD-C-148) Not more than 15% breakdown i P.O. Box 1794, Woodinville. Washington 9807.2 (206) 481 - 3456. or (206) 481 -7222 1 1 1 I Association of Rockery Contractors Standard Rockery Construction Guidelines Page 2 The test sample will be prepared and tested in accordance with Corps of Engineers Testing procedure CRD-C-148, "Method of Testing Stone for Expansive Breakdown on Soaking in Ethylene Glycol." Test requirements of not more than 15 percent breakdown will be computed by dividing the number of individual pieces of initial sample suffering breakdown (that is, separating into two or more pieces) by the total number of initial pieces in the sample. c. Soundness (MgSO4 at 5 cycles) (CRD-C-137) Not greater than 5% loss 2.01.2 Frequency of Testing: Quarry sources for rockery rock shall begin a testing program when either becoming a supplier or when a new area of the source pit is opened. The tests described in Section 2.01.1 shall be perfumed for every four, thousand (4000) tons for the first twelve thousand (12000) tons of material blasted and removed to establish that specific -.rock source. The tests shall then be performed once a year or at an apparent change in material. If problems with a specific area in a pit or with a particular material are encountered, the initial testing cycle shall be restarted. 2.01.3 Rock Density: Recognizing that numerous sources of rock exist, and that the nature of rock will vary not only between sources but also within each source, the density of the rock shall range between one hundred fifty- five (155) and one hundred sixty five (165) pcf. Typical- ly, rocks used for rockery construction shall be sized approximately as follows: Rock Size Rock weight Small One Man 58 Large One Man 210 Small Two Man 265 Large Two Man 580 Small Three Man 760 Large Three Man 1830 Small Four Man 3000 Large Four Man 4000 Five Man >5000 Six Man >7000 1 i Association of Rockery Contractors Page 3 $tandard Rockery Construction Guidelines i I Two and one-man rock, and sometimes smaller, are often used to fill surface gaps along the top of the completed rockery to create an aesthetically pleasing surface. This is an acceptable practice provided none of the events described in Section 3.01.5 occur, and that the owner prevents people from climbing or walking on the completed rockery. i In rockeries over eight feet in height, it should not be possible to move the large sized rocks (four to six -man size) with a prybar. If these rocks can be moved, the rockery should not be considered i capable of restraining any significant lateral load. However, it is both practical and even desirable that smaller rocks, particularly those used for "chinking" purposes, can be moved with a prybar to achieve the."best fit". 2.01.4 Submittals: The rock source shall present current, or most recent, test data for the testing described in Section 2.01.1 on request by either the rockery contrac- tor, the client or the applicable municipality. 3.01 Rockery Construction 3.01.1 General: Rockery construction is a craft and of the depends largely on the skill and experience i builder. A rockery is a protective system which helps to retard the weathering and erosion process on an exposed cut or fill soil face. While by its nature (the mass, size and shape of the rocks) it will provide some degree of retention, it is not a designed or engineered system in ' the sense a reinforced concrete retaining wall would be i considered designed or engineered. The degree of reten- tion achieved is dependant on the size of rock used; that is, the mass or weight, and the height of the wall being constructed. The larger the rock, the more competent the i wall. To accomplish this, all rockeries in excess of four 1 feet in height should be built on a "mass" basis. i All rockeries constructed in front of cuts and fills in excess of eight feet in height should be constructed in the accordance with this standard and geotechnical supplemental recommendations which should be i engineers provided before bidding or the start of construction. The same geotechnical. engineer should be retained to monitor i rockery construction and to verify, in writing, that the in general accordance with this rockery was constructed ARC standard and with his supplemental recommendations, in a professional manner and of competent and suitable mater- ials. J Association of Rockery Contractors Page 4 Standard Rockery Construction Guidelines 3.01.2 Geotechnical EAcrineer: The geotechnical engineer retained to provide necessary supplemental rockery construction guidelines shall be a practicing geotech- nical/civil engineer licensed as a professional civil engineer in the State of Washington who has at least four years of professional employment as a geotechnical engineer in responsible charge, including experience with fill construction and stability and rockery construction. The geotechnical engineer should be hired either by the rockery contractor or the client. 3.C1.3 Responsibility: The ultimate responsibility for rockery "design" and construction should remain with the rockery builder. However, rockeries protecting moderate to thick fills, with steep sloping surfaces above or below them, with multiple steps, with foundation or other loads affecting them, protecting sandy or gravelly soils subject i to ravelling, with seepage or wet conditions, or that are more than eight feet in height, all represent special conditions and require consultation and/or advice from qualified experts. 3.01.4 Workmanship: All workmanship is guaranteed by the rockery contractor and all materials are guaranteed by supplying quarry for a period .of six years from the date of completion of erection, providing no modification or changes to the conditions existing at the time of comple- tion are made. 3.01.5 Chancres to Finished Product: Such changes limited to, excavation of include, but are not nc.ressarily ditches or trenches within a distance of less than 1.5 times the rockery height measured from the toe of the rockery, removal of any material from the subgrade in front of the rockery, excavation and/or removal of material from any location behind the rockery within a distance at least equal to the rockery's height, the addition of any surcharge or other loads within a similar distance of the top of the rockery, or surface or subsur- face water forced, directed, or otherwise caused to flow I behind the rockery in any quantity. 1 1 A 1 1 1 1 1 1 Association of Rockery Contractors Standard Rockery Construction Guidelines Page 5 3.01.6 -Slopes: Slopes above rockeries should be kept as flat as possible, but should not exceed 2:1 (Horizon- tal:Vertical) unless the rockery is.designed specifically to provide some restraint to the load imposed by the slope. Any slope existing above a completed rockery should be provided with a vegetative cover by the owner to help reduce the potential for surface water flow induced erosion. It should consist of a deep rooted, rapid growth vegetative mat and typically will be placed by hydroseed-• ing and covered with a.mulch. It is often useful to overlay the. seed'. and mulch with either pegged in -place jute matting, or some other form of approved geotechnical.fabric, to help maintain the seed in -place until the root mat has an opportunity to ger- minate and take hold. 3.01.7 Monitoring: All rockeries constructed against cuts or fills in excess of -eight feet iw:height shall be periodically monitored during construction by the geotech- nical engineer to verify the nature and quality of the materials being used are appropriate,. that the construc- tion procedures are appropriate, and that the wall is being constructed in a generally professional manner and in accordance with this ARC standards and any supplemental recommendations. On completion of the rockery, the geotechnical engineer shall -submit to the client, the rockery contractor, and to the appropriate mun4,-cipality, copies of his rockery examination reports along with a final report summarizing rockery construction. 3.01.8 Fill Compaction: Where rockeries are constructed in front of a fill, it is imperative that the owner ensure the fill be placed and compacted in a manner that will provide a competent fill mass. To achieve this goal,, all fills should consist of relatively clean, organic and debris free, granular materials with a maximum size of four -inches. Ideally, but particularly if placement and compaction is to take-, place during the wet season, they should contain no more than five percent fines (silt and clay size particles passing the number 200 mesh sieve). 1 Association of Rockery Contractors Page 6 Standard Rockery Construction Guidelines I All fills should be placed in thin lifts not exceeding ten inches in loose thickness. Each lift should be compacted J to at least 90 percent of the maximum dry density, as determined by ASTM Test Method D-1557-78 (Modified Proctor), before -any additional fill is placed and compacted. In -place density tests should be performed at random locations within each lift of the fill to verify this degree of compaction is being achieved., 3.01.9 Fill Construction and Reinforcement: There are two methods of constructing a fill acjainst which to build a rockery. The first, which typically applies to rock- eries of less than eight feet in height, is to overbuild and then cut back the fill. The second, which applies to all rockeries in excess of eight feet in height, is to construct the fill using a geogrid or geotechnical fabric reinforcement. �i Overbuilding the fill allows for satisfactory compaction of the fill mass out beyond the location of the fill face to be protected. Overbuilding also allows the earthwork contractor to use larger and more effective compaction equipment in his compactive efforts, thereby typically achieving a more competent fill mass. Cutting back into the well compacted fill also typically results in con- struction of a•competent near vertical fill face against which to build the rockery. For the higher rockeries the use of a geogrid or geotech- nical fabric to help reinforce the fill results in construction of a more stable fill face against which to construct the rockery. This form of construction leads to �j a longer lasting and more stable rockery and helps reduce the risk of significant long term maintenance. This latter form of construction requires a design by the geotechnical engineer for each specific case. The vertical spacing of the reinforcement, the specific type of reinforcement, and the distance to which it must extend back into the fill, and the amount of lapping must be determined on a rockery -by -rockery basis. Association of Rockery Contractors Page 7 Standard Rockery Construction Guidelines 3.01.10 Rockery Keyway: The first step in rockery 'construction, after general site clearing and/or general i excavation, is to construct a keyway in which to build the rockery. The keyway shall comprise a shallow trench of ' between twelve (12) and eighteen (18) inches in depth, extending for the full length of the rockery, and inclined back slightly towards the face being protected. It is typically dug as wide as the rockery (including the width of the rock filter layer). If the condition of the protected face is of concern, the keyway should be constructed in sections of manageable length, that is of a length that can be constructed in one shift or one days work. iThe competency of the keyway subgrade to support the ' rockery shall be verified by probing with a small diameter ' steel - rod. The rod shall leave a diameter of between three -eights and one-half inch, and shall be pushed into the subgrade in a smooth unaided manner under the body weight of the prober only. Penetration of. up to six inches, with some difficulty, ' shall indicate a "competent" keyway subgrade unless other factors in the geotechnical engineer's opinion shall indicate otherwise. Penetration in excess of six inches, or of that depth with ease, shall indicate a 'soft" subgrade and one that could require treatment. Soft areas of the- subgrade can be "firmed up" by tamping a layer of coarse quarry spalls into the subgrade. 3.01.11 KeNrwav and Rockery Drainage: On completion of i keyway excavation, a shallow ditch or trench, approxi- mately twelve (12) inches wide and deep, should be dug along the rear edge of the keyway. A minimum four -inch diameter perforated or slotted ADS drain pipe, or equiv- alent approved by an engineer, should be placed in this shallow trench and should be bedded on and surrounded by a free -draining crushed rock. Burial of the drain pipe in this shallow trench provides protection to the pipe and helps prevent it from being inadvertently crushed by pieces of the rockery rock. This drain pipe should be in- stalled with sufficient gradient to initiate flow, and should be connected to a positive and permanent discharge. 1 1 1 Association of Rockery Contractors Standard Rockery Construction Guidelines Page 8 Positive and permanent drainage should be considered to mean an existing, or to be installed, storm drain system, a swale, ditch or other form of surface water flow collection system, a detention or retention pond, or other stable native site feature or previously installed collection system. 3.01.12 Rockery Thickness: The individual rockery thickness, including the rock filter layer, should be at least 40 percent of the rocker height. Unless otherwise specified in writing, the individual rocks should be arranged in a single course which, when measured to include the filter layer, is equal to the required rockery thickness. 1 1 1 1 1 1 1 1 3.01.13 Rock Selection: The contractor should have sufficient space available so that he can select from among a number of stockpiled rocks for each space in the rockery to be filled. - Rocks which have shapes which do not match the spaces offered by the previous course of rock should be placed elsewhere to obtain a better fit. Rock should be of a generally cubical, tabular or semi - rectangular shape. Any rocks of basically rounded or tetrahedral form should be rejected or used for filling large void spaces. Smaller rocks (one to two -man size, or smaller) are often used to create an aesthetically pleasing "top edge" to a rockery. This is acceptable provided none of the events described in Section 3.01.5 occur, and that people are prevented from climbing or walking on the finished rockery. This is the owner's responsibility. 3.01.14 Rock placement: The first course of rock should be placed on 'firm unyielding soil. There should be full contact between the rock and soil, which may require shaping of the ground surface or slamming or dropping the rocks .into place so that the soil foundation conforms to the rock face bearing on it. As an alternative, it is satisfactory to place and tamp crushed rock into the subgrade to tighten it up. The bottom of the first course of rock should be a minimum of twelve (12) inches below the lowest adjacent site grade. 1 Association of Rockery Contractors Page 9 Standard Rockery Construction Guidelines ' As the rockery is constructed, the rocks should be placed so that there are no continuous joint planes in either the vertical or lateral direction. Each rock should bear on at least two rocks below it. Rocks should be placed so that there is score bearing between flat rock faces rather than on joints. Joints between courses should slope downward towards the material being protected (away from the face of the rockery). 3.01.15 Face Inclination: The face of the rockery should ' be inclined at a gradient of about 1:6 !Noriaontal:- Vertical) back towards the face being protected. The inclination should not constructed flatter than 1H:4V. 3.01.16 Voids: Because of the nature of the product used to construct a rockery, it is virtually impossible to avoid creating void spaces between individual rocks. ' However, it should be recognized that voids do not necessarily constitute a problem in rockery construdtion. Where voids of greater than six inches in dimension exist in the face of a rockery they should be visually examined to determine if contact between the rocks exists within the thickness of the rockery. If contact does exist, no further action is required. However, if there is no rock contact within the rockery thickness the void should be "chinked" with a smaller piece of rock. If a void of greater than six inches exists in the rear face of the rockery, it should be "chinked" with a smaller rock. 3.01.17 Filter Laver: In order to provide some degree of drainage control behind the rockery, and as a means of helping to prevent loss of soil through the face of the rockery, a drainage filter shall be installed layer between the rear face of the rockery and the soil face a being protected. This filter layer should be at- least twelve (12) inches thick; and for walls in excess of eight feet in height, it should be at least eighteen (18) inches thick. It should be composed of four inch minus crushed rock, or other material approved by the geotechnical engineer. If one of the rockery rocks extends back, to the exposed soil face, it is not necessary that the filter rock layer extend between it and the soil face. i ' Association of Rockery Contractors Page.10 Standard Rockery Construction'Guidelines i In the event seepage is encountered emanating from a protected face, we recommend the use of a well -graded filter layer. We do not recommend the use of a geotech- nical fabric for other than coverage of relatively small and isolated seepage areas because it has been the industry's experience that the filter fabric tends to clog rapidly. This quickly leads to a buildup of hydrostatic pressure which can subsequently cause failure and collapse of the rockery and is to be avoided. This clogging is apparently due to the virtuar impos- sibility of achieving full contact between the soil face, fabric and rock filter material. If full surface contact cannot be achieved, there is often a tendency for the soil materials to flush from the protected face into the "Pockets" in the fabric which leads, to the aforementioned clogging. 3.01.18 Surface Drainage: It is the owner's respon- sibility to intercept surface drainage from above the rockery and direct it away from the rockery to a positive and permanent discharge -well below and beyond the toe of the wall. Use of other drainage control measures should be determined on a case -by -case basis by the geotechnical engineer prior to bidding on the project. 1 i 4/20/88 1 •� • �• lay 6D - • ya H _ „. • ��• •.. • • 1 • e•e • 111 ° Z �liltrot • • Y1 • �• — D 1 N •e 3 8 Fig. A. ROCKERY SECTION Fig. B. ROCKERY ELEVATION SCHEMATIC ONLY — NOT TO SCALE NOT A CONSTRUCTION DRAWING NOTES: Rockery construction is a craft and depends largely on the skill and experience of the builder. A rockery is a protective system which helps retard the weathering and erosion process on an exposed soil face. While by its nature (mass, size and shape of the rocks) it will provide some degree of retention, it is not a designed or engineered sys- tem in the sense a reinforced concrete retaining wall would be considered designed or engineered. The degree of retention achieved is dependent on the size of the rock used; that is, the mass or weight, and the height of the wall being construc- ted. The larger the rock, the more competent the wall. Rockeries should be considered maintenance items that will require periodic inspection and repair. They should be located so that they can be reached by a contractor if repairs become necessary. Maximum inclination of slopes behind rock walls is 2:1 (Horizontal:Vertical) Minimum embedment D a 12 inches undisturbed native soil or compacted fill placed in accordance with report recommendations. Maximum rock wall height H - feet. Rockeries greater than 8 feet in height to be installed under periodic observation of the geotechnical engineer. Rocks placed in the lower two-thirds of the wall should be 5 to 6 man rock, 5000 lbs. or larger. Rocks placed above this level should gradually decrease in size with increasing wall height using 3 to 5 man rock, 760 to $000 lbs. The long dimension of the rocks should extend into the earth to provide maximum stability. Rocks should be placed to avoid continuous Joint planes in vertical or lateral directions. Each rock should bear on two or more rocks below it, with good flat -to -flat contact. All rockeries over 4 feet in height should be constructed on basis of wall mass, not square footage of face. Approximate Approximate Weight - lbs. Volume (0) 1 Man 58,210 0.9 - 4.0 2 Man 265,580 4.1.- 8.2$• 3 Man 760 - 1830 12.3 - 27.1 4 Man 3000 - 7000 49.0 - 76.0 5 Man 5000 76 6 Man 7000 3.00 Reference: kg cal quarry weight study using average weights of no less than six kocks bf each man size conducted in January, 1988. LEGEND: • Drainage materials to consist of ;•:;e• clean angular well -graded quarry spalls, with 3-inch maximum size, or other material approved by the geotechnical engineer Surface seal; may consist of imper- vious soil or asphalt Ill�lil= Undisturbed firm Native Soil —111 1 Drain pipe; 4-inch minimum diameter, perforated or slotted rigid plastic O ADS pipe laid with a positive gradient to discharge under control well away from the wall. TYPICAL ROCKERY DETAILS I Association of Rockery Contractors Prof. No. 1 Date Plate 1 1 1 1 1 1 1 1 1 1 1 1 i 1 i i Ms. John Thoresen Sequoia Ridge Partners 15621 - 48`b Place West Edmonds, Washington 98026 Geo Group Northwest, Inc. Project File DISTRIBUTION Geo Group Northwest, Inc. 4 copies 1 copy 1 LEGAL_DESCRIFTION (PLAT THAT PORTION OF THE SOUTHWEST QUARTER OF THE SOUTHWEST QUARTER OF SECTION 5, TOWNSHIP 27 NORTH, RANGE 4 EAST, W.M., MORE PARTICULARLY DESCRIBED AS FOLLOWS: LOT "B", OF THE LOT LINE ADJUSTMENT IN THE,SNOHOMISH COUNTY RECORDS UNDER AUDITOR'S FILE NO. 9107030640, BEING A PORTION OF LOT 53 AND THE NORTH HALF OF LOT 52, PLAT OF MEADOWDALE BEACH, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 5 OF PLATS, PAGE 38, RECORDS 0171 SNOHOMISH COUNTY, WASHINGTON. TOGETHER WITH THAT PORTION OF THE SOUTH HALF OF SAID LOT 52 LYING NORTHERLY OF A LINE BEGINNING AT A POINT ON THE EAST LINE OF LOT 52 THAT IS 66.12 FEET NORTH AS MEASURED ALONG SAID EAST LINE FROM THE SOUTHEAST CORNER OF SAID LOT 52; THENCE NORTH 68'03'00" WEST A DISTANCE OF1 269.35 FEET TO THE NORTH LINE OF SAID SOUTH HALF AND THE TERMINUS OF THE HEREIN DESCRIBED LINE. I SHEET INDEX 1 COVER SHEET 2 CLEARING, GRADING AND TIES CI PLAN 3 CLEARING, GRADING AND TES C NOTES AND DETAILS 4 STORM DRAINAGE AND UTILITY PLAN 5 STORM DRAINAGE AND UTILITY NOTES AND DETAILS CALL 7w UTILffY LOCATES BEFORE YOU DIG ii0f l a•"*a oil 11.10-9-0 r x a 1 A, �MtxwAa+bfliw.r ,er,..uu.s�!. f`� I BENCHMARK 0 50 100 co • I CD \ \2�,2�,22 < - V do S LORIAN WOODS VOL 51, POS. 145 do 146 \49,221 SF co \ \00 00 OA cy \4. ,892 SF\ ` L-P ZONE E (TYP) \ / �s JEANINE L GASPER 100 N �\ / w N'11 305— \ \ \ \ \ \ \ \ BO -� \ to 122.07' I Z \\ \ \\ \ x \ \\ I \� \? N89.38'04"W 9. NZ GREGORY S. CASPER JOHN L JOHNSON \ INGRESS, EGRESS UTILITY EASEMENT \ I\ � Ili WESTMONT VIEW DIV. 2 VOL 36. PG. 25 ,m N �M' LUND'S GULCH 156TH ST SW 3 ic i3 3 aI COD 1160TH ST SW co to \ �Z © 019 fa ';�- PROJECT SITE � jo LIL 01 ® Iv1111 1 1 IVI/"lr •7Vf5 k 1"-1000' DEVELOPER JOHN THORESEN weea EDMONDS, WASHINGTON 98026 TELEPHONE: (425) 7 3-458 yea Ste- 3 i� �1 ENGINEER/PREPARER DAVID EVANS AND ASSOCIATES, INC. 1620 W. MARINE VIEW DRIVE SUITE 200 FILE TON TELEPHONEw(4 5)G259- 09901 _ -- FAX:-- (425) 259-3230 ---.._ _ --- - CONTACT PERSON: JACK N. MOLVER, P.E. DATUM AND BENCHMARK DATA VERTICAL DATUM: CITY OF EDMONDS BENCH MARK INVERT ELEVATION OF EXISTING 8" PIPE IN SANITARY SEWER MANHOLE IN N. MEADOWDALE ROAD; 45± FEET NORTH OF THE N.W. PROPERTY CORNER. ELEVATION 143.09 RECEWED DEC 2 7 1999 PERMIT COUNTER PW 110 APPROVED FOR CONSTRUCTION CITY OF EDMONDS C Lu A u as Lu A t 4/ • Lu r 1 f 7/? 70✓✓� AL 141 STREET FILE 11 11 it it tl, 11 ti rT vj Ott 41, 4-1 i kill SUji ue ke >) it xI rd, 'IN. Al C ATCH 'BASIN' it Ciotti. 7 Nr 502,25 I IN LK checked by, iM MD rl> atlu Feb re A 54 REGi P mary ECT rep Md Ilp lull it Ilk rT A 4RG I 7-20--&-v w LEGAL DESCRII'110N (PLAT THAT PORTION OF THE SOUTHWEST QUARTER OF THE SOUTHWEST QUARTER OF SECTION 5, TOWNSHIP 27 NORTH, RANGE 4 EAST, W.M., MORE PARTICULARLY DESCRIBED AS FOLLOWS: LOT "B", OF THE LOT LINE ADJUSTMENT IN THE SNOHOMISH COUNTY RECORDS UNDER AUDITOR'S FILE NO. 9107030640, BEING A PORTION OF LOT 53 AND THE NORTH HALF OF LOT 52, PLAT OF MEADOWDALE BEACH, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 5 OF PLATS, PAGE 38, RECORDS OF SNOHOMISH COUNTY, WASHINGTON. TOGETHER WITH THAT PORTION OF THE SOUTH HALF OF SAID LOT 52 LYING NORTHERLY OF A LINE BEGINNING AT A POINT ON THE EAST LINE OF LOT 52 THAT IS 66.12 FEET NORTH AS MEASURED ALONG SAID EAST LINE FROM THE SOUTHEAST CORNER OF SAID LOT 52; THENCE NORTH 68'03'00" WEST A DISTANCE OF 269.35 FEET TO THE NORTH LINE OF SAID SOUTH HALF AND THE TERMINUS OF THE HEREIN DESCRIBED LINE. SHEET INDEX 1 COVER SHEET 2 CLEARING, GRADING AND TESC PLAN 3 CLEARING, GRADING AND TESC NOTES AND DETAILS 4 STORM DRAINAGE AND UTILITY PLAN 5 STORM DRAINAGE AND UTILITY NOTES AND DETAILS 6 DRIVEWAY PROFILE AND DETAILS CALL FOR Ui1LITY LOCATES BEFORE YOU DIG �s , ...,«.m. . ...,...:7'^+•-- t..2= LORIAN WOODS VOL 51, PGS. 145 & 146 i i N / / ,�'G' / / JEANINE L CASPER \' V N89'38'04" W 71 ff, j �68-va�a JOHN L JOHNSON / h -IVY \ \ INGRESS, IEGMS & UTILITY EASEMLNT I 1 \� GREGORY S. CASPER WESTMONT VIEW DIV. 2 VOL. 36, PG. 25 NOnMA 3 LUND'S GULCH I I z f-- _ 156TI-1 ST SW--7- I I r_t 3 Q I Q ul co N /W�� V) 4' a ST SW �1 o� �; .. --1160TH 0 W LL)16 Q�o �� IS I..........._..� 1 1 ( z 0 z CA 164TTI ST sw ^ 1 1 !/♦ in wo � ...... r Q I0 164THlu OI PROJECT SITE 81 O� io I �P: SCAM 1"-10W DEVELOPER JOHN THORESEN 15621 48TH PLACE W. EDMONDS, WASHINGTON 98026 TELEPHONE: (425) 424-3049 ENGINEER/PREPARER DAVID EVANS AND ASSOCIATES, INC. 1620 W. MARINE VIEW DRIVE SUITE 200 EVERETT, WASHINGTON 98201 TELEPHONE: (425) 259-4099 FAX: (425) 259-3230 C014TACT PERSON' JACK N. MOLVER, P.E. DATUM AND BENCHMARK DATA VERTICAL DATUM: CITY OF EDMONDS BENCH MARK INVERT ELEVATIO1 OF EXISTING 8" PIPE IN SANITARY SEWER MANHOLE IN N. MEADOWDALE ROAD, 45t FEET NORTH OF THE N.W. PROPERTY CORNER. ELEVATION = 143.09 Y f N 06 �Nx � W o ``n `^"• X W cq d S' fir" ..�y"'��'Y'�•i,�:. pH t}i JRip.0 (/� LQ cq ! r �+ Z CO U) ul�' A H W A C) c� A '�C :° W i A a I i iE V) Q W U i O A d p Y V a z r O t— a� N d O = rn 0 O V) 0) o �- Q APPR D FOR CONSTRUC71ON o H z / 30 o� w W o a IY OF EDMONUS DAIS V) Pi a r i i I - _ � T. 27 N., R. 4E., W.M. A PORTION OF THE SW1 /41 SECTION , .- 0 04111110 l '� } � �i 0 15 30 60 i / CONSTRUCTION NOTES AND SEQUENCE /I I '_1 \_--ss / / WITH CITY OF EDMONDS. / /�; / / / / /\ \ \ \ 12nd AVENUE / W�----- / / �/ 1 SCHEDULE AND ATTEND PRECONSTRUCTION MEETING \ �y/,\ o i SNOT OPEN) / -SD �_--SS I SD — 1[ \ — SD o�/ / / / / / // 3 SF ' lw— _ �2 INSTALL STORM DRAINAGE STRUCTURES, PIPES, DETENTION PIPE AND PAVED /S�-- -_ - -�' `� / / o / / OAD PER PLAN SHEET 4 OF 6. �SS�____-�.,�1-.7-ss--� / / � / / / / ,y�h / / / / ACCESS R / / / roP --F HPA FROM W.D.F.W. SHALL BE OBTAINED ,375.26 / / / l / / / / A HYDRAULIC PROJECT APPROVAL ( ) / N 47 58 �� / CONSTRUCTION. 24.68' � S ROAD STREAM CROSSING f / / 162.32 \ FOR ACCESS C� f STREAM AND ALONG CLEARING LIMITS WHERE SHOWN. / / LIMIy OF •6LEARINi; O3 INSTALL SILT FENCE ALONG IGNIFICANT TREES. / / ''��, \ '�f \ - - / �,�� / / // / / 6 Sc RA06G/(T�(P) NO MACHINE CLEARING ALLOWED. MEANDER AROUND S Q / / n / �- - - - - - - - - - - - - / _ _ - / _ _ / O CONSTRUCT SEDIMENT TRAP WHERE SHOWN PER DETAIL 3, SHEET 3 OF 6. O / \ / i •� \ / I / I / To / / / / / / / / / /co 4 4 5 CONSTRUCT TRENCH BEHIND SILT FENCE WHERE SHOWN PER DETAIL , SHEET 3 OF 6. CLEAR WITHIN SPECIFIED LIMITS. STOCKPILE TOPSOIL IN DESIGNATED AREA AND COVER WITH PLASTIC SHEATHING. / /yam , F ADJOINING OWNER. O /// / / v / // � �� _ ` �� 7 RELOCATE EXISTING GARDEN SHED AT DIRECTION 0 ENTRANCE WHERE SHOWN PER DETAIL 1, SHEET 3 OF 6. 8 INSTALL STABILIZED CONSTRUCTION o O / / �, __/ / \ \ I I \ o GARAGE / , J / / / Wig, /I / ` w 9 STOCKPILE AND STAGE CONSTRUCTION FROM DESIGNATED AREA. \ I rfi 10 / ' o� /' / / \ \ / I / I / 34 052 /SF / / 411 �1` ; ; ` " / INGRE �, EGRESS &� O � UTILI EASEMENT 1 ` cam/ ,/% J/ :.." / O10 ROUGH GRADE DRIVEWAY AND LOTS 1, 2 AND 3. r©nJ I I \ / \ AND GRADED A TIME OF HOUSE CONSTRUCTION. / �I 0° / / f $ r" - LOT 4 SHALL BE CLEARED UAL PER GEOTECI INICAL / ' / �/ \ / / \ WALLS KEYSTONE OR EQUAL) / � / { t LL ROCKERY OR BLOCK ( � / \ J 11 INSTALL AND/OR MANUFACTURES SPECIFICATIONS. / i/ / \ / gr ��.•• NSA \ 8,892 SF/ ; I / / / � jI'"'' �'�':,�`,�'" 7.z 7 ENGINEERS RECOMMENDATIONS / 12 INSTALL UNDERGROUND UTILITIES. �/ / / / /\ / / \m / rvll _ 13 MULCH AND HYDROSEED EXPOSED SOILS EXCEPT DRIVEWAYS. �- / / / / \. GARAGE / 2 ��// / �/ / I / /� tf I/ _a• io''vF / / GRADE AND PAVE DRIVEWAYS. / /\ j / // /I /j�� lob / �y eo"s 14' FINE \ \ y� /j IRRIGATION SYSTEM TO BE SEVERED AND ABANDONED. 15 EXISTING 1 - / c � -_ r . � � N c��.� ��=- Cv�-.�,�-��"�...::..�.r �� : c;-� ► � �-��-r-•�� fi� _ - -�- 1 � \ / / / / / /\ � / / / / j H_ , / /' \ �s / / 11 m ' � _ / ' :, / � n V c �:��,.-�:1r� �.; �.I LEA I N a r ��1.__�.�_,�c�.I_1_.i_ RH HEIGHT OF ROC KERY=�G'�= �= �4-� =� + '� �y g EX HOUSE SF = SILT FENCE PER DETAIL 2, SHEET 3 \/ / / \ ; / /\ �o v / F- r � IV 41 49,221 Sy \ // \ / �o{'4Y�;/ // \ ``♦/,� / SF // --_ / /! I \ / / / �/ / \ / / .R ' , / \ � � ,� STOCKPILE & 9 2 / �~ / m�,\ \ / OF CLEARING / / /AR'12 �6 �\ J I \ , U 15 / CONSTRUCTION O \ i 2 ! / / �\ /\ / o ( 1 I STAGING (6)LIMIT & GRAISING (TYP) / 4 �\ /RH=�o' 11 1 J ON01 17 36 E (TYP) / \ I \ l \ I r �`� 58.71' / /pop\ l / r , 222 5 \� cu, � � \ /( I — — > '3 i 1 fig. • 17.5' 3 / / ``� 11�y' Y �� / f t A1, 1cs i 2 // // / I �• ' / l / 411�/ _1_e o 221,86' 1 499.17 2 ./ 30/1 -- TOP OF BANK 153.89' NO1'17'36"E SOIL STABILIZATION NOTE ESC MINIMUM REQUIREMENT - STABILIZATION OF EXPOSED AREAS ALL SOILS EXPOSED BY LAND DISTURBING ACTIVITIES SHALL BE STABILIZIED BY SUITABLE APPLICATION OF BMP'S, INCLUDING, BUT NOT LIMITED TO, SOD, HYDROSEEDING, OR OTHER VEGETATION, PLASTIC COVERING OR MULCHING. ALL BMP'S SHALL BE SELECTED, DESIGNED, AND MAINTAINED IN ACCORDANCE WITH THE MANUAL. THE EXPOSED SOILS SHALL BE STABILIZED ACCORDING TO AN APPROVED TIMETABLE. (TYPICALLY, NO SOILS SHALL REMAIN EXPOSED FOR MORE N TWO DAYS 0) D NO MORE THAN SEVEN (7)DAYS ROMAMY 1 THROUGH SEPTEMBER 30 \ I o LIMIT OF CLEARING O I N °° \ & GRADING (TYP) I 00 - \ I z \�------------ --j 123.42' to N APPROVED FO l CITY OF EDMONDS ENGINEER CLEARING AND GRADING ° D D ATE 0 0 0 IN, z 0 z n z 0 a IIn LLI 00 j N � J U) w n�. V) E-" W x Z J U Z 6— U U O A L1 o M o O O II �- 0 F— o~ W r U Z vvi A a FL A PORTION OF THE SW QUARTER, SECTION 5, T27N, R4E, WM SrM alMING AND T.EACE. NOTES 1. Non-compliance with the erosion control requirements, water quality requirements and clearing limits violations may result in revocation of project permits, plan approval and bond foreclosures. 2. Prior to any site construction to include clearing/logging or gradin the site/lot clearing limits shall be located and field identified by the project surveyor%ngineer as required by these plans. The project surveyor/engineer's name and telephone number is David Evans and Associates, Inc. (425)259-4099. 3. Prior to any site work, the contractor shall contact the City of Edmonds Engineer to schedule a preconstruction conference. Due to field changes (revisions), engineered as-builts shall be required prior to site approval. 4. The temporary erosion/sedimentation control facility shall be constructed prior to any grading or extensive land clearing in accordance with the approved temporary erosion/sedimentation control plan. These facilities must be satisfactorily maintained until construction and landscaping is completed and the potential for on -site erosion has passed. 5. All site work must comply to Chapter 33 of the Uniform Building Code (latest edition). 6. All earth work shall be performed in accordance with city standards. 7. If cut and fill slopes exceed a maximum of two feet horizontal to one foot vertical, a rock or concrete retaining wall may be required. All rock retaining walls greater than eight (8) feet in height are to follow city specifications and to be designed and certified b a civil engineer experienced in soils mechanics (see Soils Report for recommendations. 8. Stockpiles are to be located in safe areas and adequately protected by temporary seeding and mulching. HYDROSEED preferred. 9. All earthwork and construction related activities shall be per tiie recommendations outlined in the Geotechnical engineers soils report. 10. The Geotechnical engineer shall examine all stripped subgrade areas and approve rolling operations prior to the start of fill placement or earthwork. Stripping depth shall be established by the Geotechnical engineer. 11. The Geotechnical engineer shall perform field density testing of structural fills as needed during placement and observe the grading and earthwork operation. FILTER FENCE 1. The filter fabric shall be purchased In a continuous roll cut to the length of the barrier to avoid use of joints. When joints are necessary, filter cloth shall be spliced together only at a support post, with a minimum 6 inch overlap, and both ends securely fastened to the post. 2. Posts shall be spaced a maximum of 6 feet apart and driven securely into the ground a minimum of 30 inches (where physically possible). 3. A trench shall be excavated approximately 8 inches wide and 12 inches deep along the line of posts and upslope from the barrier. The trench shall be constructed to follow the contour. 4. When slit film filter fabric is used, a wire mesh support fence shall be fastened securely to the upslope side of the posts using heavy-duty wire staples at least 1 inch long, tie wires or hog rings. The wire shall extend Into the trench a minimum of 4 inches and shall not extend more than 36 inches above the original ground surface. 5. Silt film filter fabric shall be wired to the fence, and 20 inches of the fabric shall extend into the trench. The fabric shall not extend more than 36 inches above the original ground surface. Filter fabric shall not be stapled to existing trees. Other types of fabric may be stapled to the fence. 6. When extra -strength or monofilarrient fabric and closer post spacing are used, the wire mesh support fence may be eliminated. In such a case, the filter fabric is stapled or wired directly to the posts with all other provisions of Filter Fence Note 5 applying. Extra care should be used when joining or overlapping these stiffer fabrics. 7. Local governments may specify the use of properly compacted native material. In many instances, this may be the preferred alternative because the soil forms a more continuous contact with the trench below, and use of native materials cuts down on the number of trips that must be made on and off -site. If gravel is used instead, the trench shall be backfilled with 3/4-inch minimum diameter washed gravel. Care must be taken when using gravel to ensure good contact between the fabric and the trench bottom to prevent undercutting. 8. Filter fabric fences shall be removed when they have served their useful purpose, but not before the upslope .area has been permanently stabilized. Retained sediment must be removed and properly disposed of, or mulched and seeded. Filter Fence Maintenance 9. Inspect immediately after each rainfall, and at least daily during prolonged rainfall. Repair as necessary. 10. Sediment must be removed when it reaches approximately one third the height of the fence, especially if heavy rains are expected. 11. Any sediment deposits remaining in place after the filter fence is no longer required shall be dressed to conform with the existing grade, prepared and seeded. 12. All temporary erosion and sediment control measures shall be removed within 30 days after final site stabilization is achieved or after the temporary "Best Management Practices" are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil areas resulting from removal shall be permanently stabilized. TEMPORARY GnAVEL CONSTRUCTION Ei IMNCE 1. AGGREGATE: Ballast (WASH DOT std. spec. 9-03.9(1). 2. ENTRANCE DIMENSIONS: The aggregate layer must be at least six (6) inches thick. It must extend the full width of the vehicular ingress and egress area. The length of the entrance must be at least 100 feet. I I of remove d from s of the mud is n P site are such t hat mo t ' ions o n the 3. WASH ING: If Condit vehicle tires by contact with the gravel, then the tires must be washed before vehicles enter a public road. Wash water must be carried; away from the entrance to a settling area to remove sediment. A wash rack may also be used to make washing more convenient and effective. I 4. INSTALLATION: The area of the entrance should be cleared of all vegetation, roots and other objectionable material. The gravel shall be placed to the specified dimensions. Any drainage facilities required because of washing should be constructed according to local government specifications. If wash racks are used, they should be installed according to manufacturer's specifications. 1 I 5. MAINTENANCE: The entrance sholl be maintained in a condition which will prevent tracking or flow of mud onto public rights -of -way. This may require periodic top dressing with 2" stone, as conditions demand. Mud dropped, washed, or tracked from vehicles onto roadway or into storm drains must be removed immediately. WDRJSEEDING 1. CONSTRUCTION ACCEPTANCE: Will be subject to a well -established groundcover that fulfills the requirement of the approved construction plans. 2. All disturbed areas such as retention facilities, roadway back -slopes, etc. shall be seeded with a perennial ground cover grass to minimize erosion. Grass seeding will be done using an approved HYDROSEEDER or as otherwise approved by the City of Edmonds. 3. PREPARATION OF SURFACE: All areas to be seeded shall be cultivated to the satisfaction of the county inspector. . This may be accomplished by dicing, raking, harrowing or other acceptable means. 4. Immediately following finish grading, permanent vegetation (consisting of rapid persistent and legume) will be applied (minimum 80# per acre). This is to include the following: 20% annual, perennial or hybrid rye grass, 40% Creeping Red Fescue, 40% White Clover. HYDROSEED required. 5. FERTILIZER: Shall be applied at 400# per acre of 10-20-20 (10 pounds per 1100 square feet) or equivalent. TEMPORARY COVER FRACMES= 1. Disturbed areas which are to remain without permanent cover for more than 30 days, shall be stabilized by providing temporary seeding, mulching, matting, or clear plastic covering as a guard against erosion. TEMPORARY SEEDING OF STTIIPPED AREAS= I I 1. Planting done in the months of July and August may require irrigation. Planting done between November 1 and March 31 will require mulching immediately after planting. 2. Seed bed should be firm with fairly fine surface. Perform all cultural operations across or at right angles to the slope. 3. Fertilize as per suppliers and/or Soil Conservation Service recommendations. Only Non -Phosphorus fertilizer shall be applied. !. 4. The following seed mixture applied at a rate of 120 Ibs/acre or other mixtures and application rates approved in advance by the City of Edmonds shall be used: Porportion Percent Percent Name i By Weight Purity Germination Redtop (Agrositis Alba) 10% 92% 90% Annual Rye (Lolium Multiflorum) 40% 98% 90% Chewing Fesque (Festuca Rubra Commutata) 40% 97% 80% (Jamestown, Banner, Shadow, or Koket) White Dutch Clover 10% 96% 90% 5. Hydroseeding with approved seed -mulch -fertilizer mixtures may also be used. 6. Seeding shall be supplied with additional moisture as needed, at rates which are controlled to prevent runoff. 7. Areas which fail to establish vegetative cover adequate to prevent erosion shall be re -seeded as soon as such areas are identified. MULCFIING AND MATT1Nt 1. Mulch materials, application rates, and specifications, shall conform to the DOE Stormwater Management Manual for the Puget Sound Basin, and shall be approved by the City of Edmonds in advance of use. 2. Erosion blankets and matting shall conform to and be installed per the DOE Stormwater Management Manual for the Puget Sound Basin, and shall be approved by the City of Edmonds in advance of use. I CLEAii PLASTIC COVEFiINW 1. Clear Plastic coverings shall have a minimum thickness of 6 mil and meet the requirements of WSDOT/APWA Section 9-1475. i 2. Covering shall be installed and maintained tightly in place by using sandbags or tires on ropes with a maximum 10 foot grid spacing in all directions. All seams shall be taped or weighted down full length and there shall be at least a 1 to 2 foot overlap of i 0 a R=25' MIN._ (OPTIONAL) 12" MIN. 4"-8" QUARRY SPALLS 9 s r o- v G tiF T� 9t � co ti s�o Fss, DETAIL - TEMPORARY CONSTRUCTION ENTRANCE INFLOW 4f4 I: LEVEL BOTTOM ELEVATION PER PLAN 2' SETiLING DEPTi 1.5' SEDIMENT STORAGE j NO SCALE ILTER ABRIC ENCE STAPLES OR WIRE RINGS (TYP.) �, FILTER FABRIC MATERIAL MIRAFI 100X OR EQUAL. - 2"X2" WOOD POSTS, STANDARD OR BETTER, OR EQUIVALENT WE BURY BOTTOM OF FILTER FABRIC MATERIAL IN 8"X12" TRENCH GRADED AREA FILTER FABRIC MATERIAL --_ WIRE MESH SUPPORT FNECE FOR FILTER FABRIC _ PROVIDE WASHED GRAVEL OR COMPACTED NATIVE SOIL AS DIRECTED BY LOCAL IIII=111� 1=�' GOVERNMENT N IIII 2"X2"X14GA. WELDED WIRE / MESH OR EQUAL I -_ o I •• N o . 11= T° I =1111_ 111 = 1111-1111_ IIII I111J cV no I 6' MAX _I I-, CLEARING LIMITS N DETAIL - SILT FENCE NEWLY GRADED OR DISTURBED SIDE SLOPE. 2.00' IP-RAP PAD TRENCH -1.0' OVERFLOW DEPTH 1' DEP111 OF 2" - 4" ROCK 6.0' MIN OVERFLOW CIIA1414EL IS CONSTRUCTED BY - -EXCAVATION Qo-,-- o 3' 1 X FILTER ie FABRIC `��..........�:��..�.�:.:c':.:'i_• - - FENCE ,__1' DEPTH OF 3/4" TO 1 1/2" WASHED GRAVEL NOTE: MAY BE CONSTRUCTED BY EXCAVATION OR BUILDING A BERM 1' DEPTH OF 2" - 4" ROCK 1' DEPTH OF 3/4" - 1 1/2" WASHED GRAVEL [ Z 114DETAIL - SEDIMENT 11RAP- - NO SCALE r 2.00' v NO SCALE SILT FENCE BACKFILL WITH COMPACTED NATIVE MATERIAL. NOT: INSTALL THE SILT FENCE FIRST. AFTER THE SILT FENCE HAS BEEN INSTALLED, CONSTRUCT BERM AND TRENCH. DETAIL - SILT FENCE W BERM AND TRENCH NO SCALE 0 0 0 N 0j N J w X W ;•Z,i, O Q) %t3 O to if d, t' Ew-H }r CQ �01 w �Co0 ' win eel P_ A w El � oW to A :° E all seams. Seams should then be rolled and staked or tied. b 3. Covering shall be installed immediately on areas seeded between November 1 to March T! 30 and remain until vegetation is firmly established. i 4. When the covering is used on unseeded slopes, it shall be left in place until the next seeding period. W n at the to of the slope to prevent surface flow beneath 5. Sheeting should be toed i p the plastc. V) Y 6. Sheeting should be removed as soon as is; possible once vegetation is well established Z J z to prevent burning the vegetation. p g % A 7. Check Sheeting regularly for rips and places where the plastic may be dislodged. Z Contact between the plastic and the ground should always be maintained. Any air�� U or the plastic may rip during the next bubbles found should be removed immediately p y p 9 o W a x windy period. Re -anchor or replace the plastic as necessary. 6: A A U � I M y Vi � O v 4 O .- O = O .- O $ V) >O O H C Q Z yy ~ AND GOADING PROVED FOR CLEARING U ZW �� a �^ l/P_ CITY OF EDMONDS ENGINEER DATEiE 1U Q �7 Y 0 15 30 60 CONS"MUCTnON NOTES O1 CONSTRUCT PAVED EMERGENCY VEHICLE TURN -AROUND AT EXISTING PUBLIC ROAD END PER CITY OF EDMONDS STANDARDS. O2 MATCH EXISTING PAVEMENT EDGE AND ELEVATION. �3 INSTALL STORM DRAINAGE DETENTION SYSTEM PER DETAIL 5, SHEET 5 OF 6. A HYDRAULIC PROJECT APPROVAL FROM W.D.F.W. SHALL BE OBTAINED FOR CONSTRUCTION WITHIN THE STREAM. �4 RESTORE STREET PER CITY OF EDMONDS STANDARDS. O5 WATER SERVICE TO LOT 4 TO BE INSTALLED BY CITY OF EDMONDS FORCES AT TIME OF HOUSE CONSTRUCTION. O PAVED ACCESS ROAD TO BE USED AS FUTURE DRIVEWAY AND TURNAROUND FOR LOT 4. O7 RESTORE GROUND TO PRECONSTRUCTION ELEVATIONS. O8 INSTALL W.S.D.O.T. STANDARD BEAM GUARDRAIL. O9 INSTALL FIRE DEPT. AND EMERGENCY AID ADDRESS SIGNS FOR LOTS 1, 2 AND 3 WHERE SHOWN. 10 CLEAR VEGETATION WITHIN RIGHT-OF-WAY AS NECESSARY TO MAXIMIZE SIGHT DISTANCE. EXISTING HYDRANT 11 PROVIDE 1OLF-18" STEEL SLEEVE FOR STORM PIPE UNDER ROCKERY. 12 CONSTRUCT ROCKERY PER DESIGN BY WM. CHENG, P.E. (LATCI1 EIASIN DATED APRIL 20, 2000. TOP 20202.08 IE=158.90 (CP JJMY1 1 - v-rvv CONSTRUCT OVER EX 8"SS RIM=183.50t IE=173.20-EX 8"E,W IE=173.37-NEW 6"S CB B-2 TYPE 2 48"0 W SOLID LOCKING COVE RIM=182.00 IE=173.18 - 12"S,E,W CB B-3 TYPE 1 INSTALL AT END OF 12"CP GRATE=175.91 IE=172.91 - 12" NEW & EX IE=I72.91C:n)�\ ��ATI"ai F�ASIN ri:P 171,90 _ TOP 175.31 TO(' 171.90 SS MANHOLE I OP 200.74 IE 192.09-8"N IE 192,04-8"F IE 191.94-8"YY I BASIN 97.71 WATER MANHOLE (PRV) J! \ 6 A PORTION OF THE SW1 /4, SECTION 5, T. 27 N., N. 4 t., vv.nn. CATCH_F3.4SIN _��, �roP 225.60 , SS MANHOLE_____ s� CATCH BASIN IOP 224. 3.1 / // TOP Z. 1. 0 c, IE 2I8L24--8" TOP 222.30 ��,(i / / I ' % / \ \ / --EXPOSED 12" C11P CrM1'rCl I BASIIJ, / CATGFI 9A.5U 1 P �15.'19 ''7 p `� 'Ar TOP ?_21.62 ' �%T()P 218.89__ % 0 4 / \ /\ it / Znd /1 VGN�� 11r / (NOT OPEN) / _ _� SD - % _ - \--- --_ - _ _ - �- I j �2" BLOW -OFFS SS AIANriOLE - / / -IJ��? ------ SO _.-" ,-�Y-�-.__ - -- o ` / �� o� / + i 1-8'; LUG (1v1JJ T6P 219.55 Y �'+��` _. ---'-__ / / THRUST LOCKING 209.5� 8 IE STOP 9 BANS TOP 215.40 CT SS MANHOLE -1OP 314.0'-� IE 306.80--8" \ CATCH BASIN 10P 313.81 CATCH BASIN � -- IOP 302.47 _ \ `O S; MANHOLE I P 30.;•5g �- V 296.24-•8" \ VEHICLE TURN -AROUND fs$--- o i r .1I1-70 17 8"DI CL52 EXIFH R'. \ ` / /.- ' ,a" / / I / 1 / / �• /` / / / / 'l l'�'�� ♦ / �•ti Qlz / R �,��`4d'{'Z • / � 0��/'`� mil' �� / \ / ' I / / / N.IW`�� /<1/-Irk"!{r / /r' / / ; , / ' / / o / / / i'r / / 14-5 r ` I t Z �� / / / ' �% / / / / / / / /�,/a / GARAGE �:/ / ,f / / I / / / / / i �f• ; INGRE S, EGRESS & UTILIT EASEMLN I ry t_ 10' 2 Zz / GARAGE / ) 1, -i_ DF ATYPEIOW ° , \ oo / • GRATA=2P8.00/4+49 � ��' >lV"k �Y��. i � � • � '1'Y'�'` / / !1 _\`-\ r i TOP-L79.511 `per /IE=<; l.50 / i w \ // / 'G%B A 1 111PE 1 r 271.00 ' 6' S=2(7 �/3% •\vie `1� ' / / / I � / � °� / / / / � •... / O / / E:; HOUSE % 2 / 1 H j O / "S INLET -1 / S MH 3 PR /ATE J3+49 \/ / / / / F��' %- W 'INLET PR TECTIO 5 \ /-IjIM=260.0 ILI179.00 / \ A / / ,IE=250.00 % / ! I ( / ci SDMH A-6 TYPE 2 5 0 `I / CB A-3� APE 2 48"� / //� / / / / I / \ 10, .J W%/LOW COIJ/' ROL i UCTURE/ 5 / GRATE--259.50 o / / \ / IE=245.Oj�-12�N IE=2522,50-12 S / 15LF �12"SD ! / S=3a.13q S LID LOCKING COVER : - 12 10U7712 CMP / , S=1.00q O 6" SS 0- 2+4 TOP=23 .00 / / IE=224 TO=184.90-69- IE=173�7 V \ �w n ' 6 /� '`3 , / ,/ /% �,,,�s6 Gc\ /y, �ti,S��-----• / ��_ � � /� f � 11 ,tut. � ,( ��F�I/rV '' \ \ \ % ` �/ / // � �'��`•.� ��x`aj± V' / fy{,(�•l�vfi� / �j .4 I o5��/i // �`rG� � / I 1� pl'� €� \ \ � � ,,,,_,r - / a �'�• , / eft \ / ' i �� f \ / Fj�b�O // 4" - 1114 G- %I 0 -72"CMP 5' IENrION PIPE 5 '� �,9; a'lyyo'f�� P1 i�N'1¢% / °:`'�Hy2�'rl,�/ Z6STORMRA11111 (�. / / ,/ EASE7M TOP 154.76 GAT CI I ,13ASIIJ\ % / j' %. /� cd ,A ° /lop 151.15 :lam IE=14�5.59 JCP aJ P,IANHOLE _---- TOP '150.79 IE 143.09- 8"E II: 143.39-8"SW CA CI LB T01:' 167.16 / \ XK, / 5� IOC in %' - TOP 0r 1 ;/ �' d _ CB A-7 TYPE 2 54"0 W/ SOLID LOCKING COVER vi RIM=181.50 IE=173.78 - 36" Z ,5 DF�: a''OF BANK 91. r- 1 �d•Nrly'* '" zl wI a a �i UI CONNECT TO EX 8"DIWM 1-REMOVE EXISTING PLUG & THRUST BLOCKING 1-8" GATE VALVE (MJxFL) 3-WAIER MEIER & 11/2" WATER SERVICE LINES IN COMMON TRENCH WITH TRACER WIRE PER CITY STANDARDS TO LOTS i-WATER METER BOX FOR BLOW -OFF VENT 72ND AVENUE W 30, < i P1,14 2" COMP DEPTH CLASS 'B' ASPHALT SSMH 2 PRIVATE - RIM=226.00 IE=218.00 CB A-5 TYPE 1 1 W SOLID LOCKING 2" COMP. DEPTH CR. SURFACING TOP COURSE 4" COMP. DEPTH CR. SURFACING BASE COURSE (BASE APPROVED BY ENGINEER AND GEOTECH) LENGTH VARIES SAWCUT NEAT EDGE 2' MIN w z CE EXTRUDED CURB (TYP) PER DETAIL 1, SHEET 5 2 1 EXISTING GRADE APPROVED SUBBASE CI �Y OF EDMONDS ENGINEER NO SCALE CONSMUICWN DATE z •twi d L. a tt�` wjµy m coo) NOW . c '+ A v) M fR,. It a uj dp+1f %` tf A• l!yiy��R 44 i� `�'p f4 0, • • ! r, p� NIM 4 I�M1 .w m V) W w O rn O z a c a 1s A PORTION Or THE SW 1/4, SECTION 5, T27N, R4E, WM GENERAL NOTES 1. ALL WORK AND MATERIALS SHALL BE IN ACCORDANCE WITH CITY OF EDMONDS STANDARDS AND SPECIFICATIONS AND WASHINGTON STATE DEPARTMENT OF TRANSPORTATION 1994 STANDARD SPECIFICATIONS FOR ROAD, BRIDGE, AND MUNICIPAL CONSTRUCTION. 2. ALL WORK WITHIN THE SITE AND CITY RIGHT-OF-WAY SHALL BE SUBJECT TO THE INSPECTION OF THE CITY ENGINEER OR HIS DESIGNATED REPRESENTATIVE. 3. PRIOR TO ANY SITE WORK PERTAINING TO DRAINAGE, THE CONTRACTOR SHALL CONTACT THE CITY OF EDMONDS CHIEF INSPECTOR TO SCHEDULE A PRECONSTRUCTION CONFERENCE. DUE TO FIELD CHANGES REQUIRING REVISIONS, A REVISED CONSTRUCTION PLAN, SIGNED AND STAMPED BY THE ENGINEER OF RECORD SHALL BE SUBMITTED TO THE INSPECTOR AND APPROVED BY THE CITY ENGINEER PRIOR TO CONSTRUCTING CHANGES. 4. THE TEMPORARY EROSION/SEDIMENTATION CONTROL FACILITY SHALL BE CONSTRUCTED PRIOR TO ANY GRADING OR EXTENSIVE LAND CLEARING IN ACCORDANCE WITH THE APPROVED TEMPORARY EROSION/ - SEDIMENTATION CONTROL PLAN. THESE FACILITIES MUST BE SATISFACTORILY MAINTAINED UNTIL CONSTRUCTION AND LANDSCAPING IS COMPLETED AND THE POTENTIAL FOR ON -SITE EROSION HAS PASSED. 5. ALL STORM SEWER PIPE IN ROADS SHALL BE ADS DOUBLE WALL SMOOTH INTERIOR, N-12 T.M. POLYVINYL CHLORIDE (PVC) PIPE, SDR 35. IS ACCEPTABLE FOR LOT DRAINS. 6. ALL PIPE SHALL BE PLACED ON STABLE EARTH, OR IF IN THE OPINION OF THE COUNTY ENGINEER, THE EXISTING FOUNDATION IS UNSATISFACTORY, THEN IT SHALL BE EXCAVATED BELOW GRADE AND BACKFILLED WITH A GRAVEL MATERIAL TO SUPPORT THE PIPE. 7. THE BACKFILL SHALL BE PLACED EQUALLY ON BOTH SIDES OF THE PIPE OR PIPE -ARCH IN LAYERS WITH A LOOSE AVERAGE DEPTH OF 6", MAXIMUM DEPTH 8% THOROUG14LY TAMPING EACH LAYER. THESE COMPACTED LAYERS MUST EXTEND FOR ONE DIAMETER ON EACH SIDE OF THE PIPE OR TO THE SIDE OF THE TRENCH. MATERIALS TO COMPLETE THE FILL OVER PIPE SHALL BE THE SAME AS DESCRIBED. (REFER TO WSDOT STD. SPEC. 7-04.3(3) AND STD. SPEC. 2-03.3(14)C, METHOD B & C.) 8. ALL CATCH BASINS SHALL BE TYPE I OR TYPE II AS NOTED ON THE PLANS. 9. THE CONTRACTOR SHALL BE RESPONSIBLE FOR ADJUSTING ALL MANHOLE, INLET, AND CATCH BASIN FRAMES AND GRATES JUST PRIOR TO POURING OF CURBS AND PAVING. 10. ALL CATCH BASINS WITH A DEPTH OVER 5.0 FEET TO THE FLOW LINE SHALL BE TYPE it CATCH BASINS. 11. ALL CATCH BASIN MANHOLES, INLETS AND CATCH BASINS SHALL HAVE LOCI<ING LIDS. 12. ALL STRUCTURAL FILLS SHALL BE COMPACTED TO A MINIMUM OF 90% OF MAXIMUM DENSITY BY STANDARD PROCTOR TEST. (SEE GEOTECHNICAL NOTES ON THIS SHEET). 13. STANDARD LADDER STEPS SHALL BE PROVIDED IN ALL CATCH BASINS/MANHOLES EXCEEDING FOUR (4) FEET IN DEPTH. 15. BACKFILL TRENCH OF NEW UTILITIES SHALL BE COMPACTED TO 95% RELATIVE COMPACTION UNDER ROADWAYS AND 90% RELATIVE COMPACTION OFF ROADWAYS, AS SPECIFIED IN SECTION 2.03.3(14)D AND SECTION 2-03.3(14)8. 16. STORM WATER CONVEYANCE FACILITIES MUST BE FLUSHED AND CLEANED PRIOR TO CITY OF EDMONDS ACCEPTANCE. 20' ACCESS & UTILITY ESMT. 17' MIN - 2' MIN EXISTING GRADE EXTRUDED CURB (TYP) 4 PER DETAIL 1, THIS SHEET i ROCKERY PER DETAIL 6, THIS SHEET, I AND GEOTECHNICAL ENGINEERS 2q RECOMMENDATIONS e in 1 0-+ PERF. PIPE TO ENCLOSED DRAINAGE SYSTEM 2" COMP. DEPTH CLASS 'B' ASPHALT 2" COMP. DEPTH CR. SURFACING TOP COURSE 4" COMP. DEPTH CR. SURFACING BASE COURSE o 0ENCLOSED DRAINAGE SYSTEM (BASE APPROVED BY ENGINEER AND GEOTECH) POWER, TELEPHONE INDIVIDUAL 11/2" PE & GAS SERVICES WATER SERVICE 6" PVC SAN. SEWER ffiConMw AMEW ---- E 10" 5" 2 1 /2"- 1 1 /2" R. A v L 2 1/2" 1 xPIPE DIAL 8' r-12" (D NO SCALE o 0 FRAME AND GRATE v (SEE STANDARD PLAN FOR DETAILS); 5+ 3_ 34 A� RISER SECTION 1-#3 BAR HOOP 5' 34 q' RISER SECTION 2-#3 BAR HOOP �. #3 BAR EACH CORNEF #3 BAR EACH SIDE W aye{0 V Mlti NOTES: 1. CATCH BASINS SHALL BE CONSTRUCTED IN ACCORDANCE WITH AS1M C478 (AASHTO M 199) & C890 UNLESS OTHERWISE SHONN ON PLANS OR NOTED IN THE WSDOT/APWA STANDARD SPEOFICATIONS. 2. AS AN ACCEPTABLE ALTERNATIVE TO REBAR, WELDED WRE FABRIC HAVING A MIN. AREA OF 0.12 SQUARE INCHES PER FOOT MAY BE USED. WELDED WIRE FABRIC SHALL COMPLY TO ASTM A497 (AASHTO M 221). WIRE FABRIC SHALL IIOT BE 5" PLACED IN KNOCKOUTS. 3. ALL REINFORCED CAST -IN -PLACE CONCRETE SHALL BE 6" SECTION CLASS 4000. 4. PRECAST BASES SHALL_ BE FURNISHED WITH CUTOUTS 01 KNOCKOUTS. KNOCKOUTS SHALL HAVE A WALL 111ICKNESS OF 2" MIN. ALL PIPE SHALL BE INSTALLED IN FACTORY PROVIDED KNOCKOUTS. UNUSED KNOCKOUTS 14EED NOT BE GROUTED IF WALL IS LEFT INTACT. 5. KNOCKOUT OR CUTOUT HOLE SIZE IS EQUAL TO PIPE OUTER r DIAM. PLUS CATCH BASIN WALL THICKNESS. " 6. KNOCKOUTS MAY BE ON ALL 4 SIDES Willi MAX. DIAM. OF 20". KNOCKOUTS MAY BE EITHER ROUND OR "D" SHAPE. 12" SECTION 7• THE TAPER 014 THE SIDES OF THE PRECAST BASE SECTON AND RISER SECTION SHALL NOT EXCEED 1/2"/FT. 8. CATCH BASIN FRAME AND GRATE SHALL BE 114 ACCORDANCE WITH STANDARD SPECIFICATIONS AND MEET THE STRENGTH REQUIREMENTS OF FEDERAL SPECIFICATION RR-F-621D. MATING SURFACES SHALL BE FINISHED TO ASSURE NON -ROCKING FIT WITH ANY COVER POSITION. 9. FRAME AND GRATE MAY BE INSTALLED WITH FLANGE DCWN OR CAST INTO RISER. 10. MAX. DEPTH FROM FINISHED GRADE TO PIPE INVERT SHALL BE 5'-0". 11. EDGE OF REDUCING SECTION OR BRICK SHALL VOT BE PORE THAN 2" FROM VERTICAL EDGE OF CATCH BASIN WALL PRECAST BASE SECTION (MEASUREMENT AT THE TOP OF THE BASE) #3 BAR EACH WAY NO SCALE 5ER 54" TYPE II C.B. 1CCESS DER PLAN I ROUND SOLID LOCKING COVER MARKED "DRAIN" ELEV=183,00 LIFT ROD HANDLE -� LIFT ROD ----� z - OVERFLOW ELEV=179.78 QR ORIFICE NO. 2 ELEV=178.28 DIA=2 1/2" `PIPE SUPPORT: 3" X 0.90 72"CMP GAGE BOLTED OR IMBEDDED DETENTION 2" IN WALL AT MAX. 3' SPACING. PIPE 2LF-36"CMP 12"SD OUTLET o IE=174.28 IE=173.78 r1 \CLEANOUT GATE/SHEAR GATE LADDER STEPS SEE DETAIL STANDARD GALV. STEEL TYPE II 54" C.B. o N RESTRICIOR PLATE ::: • :.•:..,•:;.•' ... ...::,. W/ 11/2" DIA. ELEV=172.28 ORIFICE NO. 1 ELEVATION MAL CE"41 A-5 TYFE RX 2-- V'1' f W SCALE: 1 "=3'-0" �M c VVIAS •4,. 213114 BOLT LOCKING RING & COVER FINISHED GRADE .j AIR VENT - AT CROWN grLDE 2" MIN, DIA. 80LF - 72"CMP 12" RISER---- 12 GA GALV STEEL W/ 2' z 30 CORRUGATIONS MAX. :�In 1 DETENTION PIPE cam S=0.00% a F6" DEAD STORAGE _ - o _\_36" 36" MIN. DIA.----"""' IA. mom two Bonn MIN. DIA. 0 CONNECTOR CONNECTOR FLOW PIPE PIPE RESTRICTOR SDMH A-7 tu TYPE -2 CATCH BASIN Vr SDMH A-6 54" DIA. �^ TYPE 2 CATCH BASIN 54" DIA. ELEVATION VIEW NOTES: 1. NEOPRENE GASKETS REQUIRED AT ALL CMP AND CPE PIPE JOINTS. 2. ALL METAL PARTS SHALL BE CORROSION RESISTANT. STEEL PARTS SHALL BE GALVANIZED z AND ASPHALT COAT ED(TREAIMENT 1 OR BETTER). LU 3. CAPACITY OF OUTLET PIPE MUST BE EQUAL TO OR GREAI.1_R THAN ALL INLET PIPES COMBINED. P�A NO SCALE ROCK SIZE PER GEOTECHNICAL -_ RECOMMONDATIONS w � - In IIIi- v Q I M m -i ri -, w `----8" MIN. THICKNESS > = r 4"-2" QUARRY SPALLS :.: III!;: N PERF. PIPE CONNECT TO STORM III 1= I 11= I I I•- i I I DRAINAGE LINES =lTfl -1111- 4'-6" (MIN) NO SCALE API`21194 12 ro o , Cr�RY tiv •1� rtLL - �c 0 ��_IS CTION -- 6 FT '1 _ TENSAR UX1500 '---N- GEOGRIU 6 FT t� COMPACTED Flll ` 3 FT CLEAN QUARRY• ? / 3 FT �S yf. SPALL DRAIN ROCK T 1 FT 1 H1CKNESS -- `- / 4 INCH DIAM. PERF. PVC PIPE, .��c�c��<:.� ,-�PP�-�"1.r.:71-�-�A�l.-- � �:' I•�1 h-r11"..t �17-- \ ROCKERY CONSTRUCTION SPECITIIONS 1.) Rock shall be Lard, durable 6-Man (7000 lb) rock far basal 3-colliscs, remainder shall be 4-Maarock 'ia� � { j (�C� L7 �Z �� ` CJ �� j� (O �Z "j'1r-�'y� rJ K` 1• Q 2.) Long dizneosion of luck shall extend into earth and each rock should bear on two or mare rocks r" �l }1 ::_1-l�% I 3.) Drainage material y j�> - 1.,.� IPAI_! shall consist of clean quarry spells with 3 inch maximum. size 4.) Drainpipe shall be 4 inch d>ber rerfera+cd PVC ripe laid in draw: zock ivyth �adieatto ccherge laphtlilic- .. 57��-sC7 (Q =1' 14='� 5.) Rockery sball be embedded at least 18 inches and shall bear on native dense soils-- 6.) Roeketp face shad not cwzeed IH:6V (Horizontal Vertical) inclination 7.) Oeo-grids shall be 6 faoticmlgth Tensar UX1500 or uivalen laid flat onprepared S. Fill shall be an (]ravel or Pit -run free of delctesiotts or organic mttDai level surface, overlap 1 ft - S d, g al, planed is S inEh lifts & compacted 9.) All fill shall be compacted to meet or exceed 90% of modified proctor mac dry dwsity (iSTM-D-1557) ROCKERY CONSTRUCTION PROUDURE 1.) Fill bench shall be excavated, and existing topsoil, Loose soils and vegetation shall be ienwved fivm the slope 2.) Fill shall be placed $ cep acted & gC0-grids placed as shown in diagram - up to proposed xoad subgrade 3.) Placed and compacted Fill wedge area shall be cut at proposed rockery location 4.) Rockery shall be caustTticted against cut fill wedge at the same time drainage system is installed - - •.. _ . �` (f2 -1%1�-'12 `'r l_ �%1;� I6.J V---D ice- �z�-ir�� lr� + i� v t`�IG��z• �- I';wt 17P1 C rf -P_ �'L= 1',.I �• ,��t, I!.{t j-� r"7 �( /..i i �_.��• L <-D,,_! 117 •I -• �t 1�.)4�,:',t:,`71`! / A..t,•.•.r�.> �:.-'-5... �� it•J CITY OF EDMONDS ENGINEER a M s CONSTRUCTION 4 �o o DATE A jT" 'V V J QI 0 �I z z C w Q z 0 to Q A. PORTION_ OF THE S.VV_ 1-/ 1-17 b — ECTION `✓, T27N, f i4�E,,.. W.M. Y_•-_---_-.,_...._._._._ po \ � � GUARD AIL PER WSDOT IDS _...._.......___.._.__ ___...___._..._.__._ _ _.._.__. __........._..__. _..__...._•_._._..—... _......__..•.._._ _ ._..._...__....._....._ _ _._._._.._...._._.w.__ 0 0 310 OCK WALL 6 310 ---_ - _ _ _._.__M \ __-_ ____ \ \ 5 260 300 300. \ EXISIING GROUND _ --•-- - -- FINISHED GR E 290 ___....._._PROVID 1OLF-18" TEEL SLEE E S MH 3 PRI ATE ROCKE ZY S StA 3+49 \ FOR DR IN PIPE Ut DER RI =260-00 IE - 250.00 - 6" CB A-3 TYPE 2 480 EXI TING GROUND GR TE=259.50 8 ! I E = 2 45.0 0 - 1 "I� ALC' 280 r__..__..IE= 252 50 . _ 1 280 CB A-1 TYPE 1 -- GR TE=288.00 S, _._._.._.._ __ __ _ _ _ _ __. --_ _ - --- _ _ __ .�•� IE 285-00 - 12"N SOLI LOCKING OVER I \ 3 270 _.. ____ GRATE=2 4.00 1 6' SS CLEANO T - 12"N,S ----- STA 4+49 S 220 _.__ _._._.___ __ _____ _ .-- ___.—__. __ _ __._ S 6.0 RI=279.50 _ _ .___ - �SZ� - _ - - 6"SS CLEA OUT v w -271-5U.__ - - I - SS SI A 2-I 49 a RIM=230.0 CB A-5 YPE 1 _l__- 6" IE=224.00 -_ __ _ _ _ __ _ - OCKING CO ERA- W 260 _._ _ _. _.____..__... _-- _ ____ __ _ _ __ _ _ __ _ .._• __ _ ..._ _ W/ SOLI D \ Z _ GRATE=22 .00 =224 12"NE,SE \� TYPE IE 00 - x - __.._-•_---.. ._....._._._...___ _._._... ._ ... ..--------------- � G ATE= 271.0hU-.- IE 268.00 - 12"N,S 6A� SSMH----- - 2 RIVATE- 3 00 SS _ SS STA 1 49 \ 2 00 RIM=226.0 1 - _------- _ - o 1 OG IE=218.00 - 60 00 " 200 EXISTIN GROUND Q \ MEADO DALE R AD V) \ w i-- Q i 61SS HEM OUT SS STA 2-+- 9 RIM=184.00 IE=173.87 6" w.Cg q--6-- W� CONTROL TRUCTURE RIM=183. 0 IE=173.7 - 36"W IF=174.2 FINISI- ED GRADE i -10 F-12"SD I =1.00% rl III 50 _F 6"PVC =1.00% I �! SSMIj 1 ~- INSTAL OVER EX AIN SS ST 0+00 RIM="I 3.50f IE=17 .20 - EX "E,W .._---.IE=.17 37 _ -N EUV CB B-2 TYPE 2 480 W/ SOLID LOC ING COVER RIM 182.00 __ - __ _--- _- _• --- - -. IF-17.18 - OFF DMONDS ENGINEER 270 (tam o r fix: i 4 r i. p,d "ii3S" a..e .ail WAM ism r; cl ` ;a klm N 0 � o 0 v o f c 00 i N W o r,`SS rail' •� ,��;r��$.f E- II l r,21"t`k lri 4i.R�y b� � tel: 'rr :Y:`fFin��i(�iit� � i /�--�•i Ul W o co •10 z �' rti' p W U] w WCQ ►�' A o w aA, 200 3k}a"b'° 7 r�= Z Z �-(J`� V sJ 0 o o � rn o �' o V) I - V) a OZ U z w w o E-' w a ) Q a w a �l 0 50 100 24.68' co �Q v c � rf ' 3 =h`b 49,221 SF .gyp. / 30� JEANINE L. CASPER N 01'47'58"E AVENUE WEST (NOT OPEN) GREGORY S. GASPER WEST R/W LINE HELD PARALLEL WITH FOUND MONUMENTS SET BY � THE PLAT OF WESTMONT VIEW DIV. 1 (VOL 34, PGS 12 & 13) WESTMONT VIEW DIV. 2 VOL. 36, PG. 25 FOUND 5/8" REBAR &CAP (LS&A-9891) FOUND 1/2" REBAR &CAP (LS 22989/12055) - 735.74' �2 I N (7; N N O Oi , / N EASEMENT Y 34,052 SF (GROSS) I- 0 30,555 M SF (NET) 1 I z Co o I / `�� h �° ATIVE GROWTH 48,892 SF (GROSS) 46 625 SF MNET) , 6 � PROTECTION I / 20.00'<� FOUND OLD CAP IN CONC (NO ID) HELD AS WEST R/W LINE 72ND AVE W PER ROS 26-214 FOUND REBAR &CAP IN CONCRETE (NO ID) / FOUND 5/8" REBAR &CAP (RMA-7892) � FOUND NAIL IN 6" DIA CONC / I FOUND NAIL IN 9 Q� BOUNDARY / / / / / i 6" DIA CONCRETE Q,�/ FOUND NAIL IN 1 6" DIA CONCRETE �ow o I AF 27,222 SF 53 / / I 0 03 25' r / ° o JOHN L. JOHNSON coa 0 I \' NO1'17'36"E /ice �n 58.71' ----.FOUND 5/8" REBAR & CAP (RMA-7892) 1 17.5' ' 6 � ' TOP OF BANK BSBL 4,nm1 co------ cv w N 221.86' \� I �i 5154 _ 499.17 N01'17'36"E 231w R� Q1 FOUND REBAR & CAP (LS #94351 HELD AS N.W. CORNER OF LOT 53 LORIAN WOODS FOUND BRASS CAP IN VOL. 51, PGS. 145 & 14E CONCRETE MON IN CASE (RMA-4561) 153.89' WEST LINE, LOTS 52 & 53, MEADOWDALE BEACH (VOL 5, PG 38) AS ESTABLISHED BY THE PLAT OF LORAIN WOODS (VOL 51, PGS 145 & 146) HELD FOR THIS SURVEY. � REFERENCES 1. ROS 26-214 AFN 8803305001 2. ROS 31-94 AFN 9002275001 3. ROS 32-236-257 AFN 9009045001 p N u'> co 4. PLAT OF MEADOWDALE BEACH z� VOL 5, PG 38 5. PLAT OF WESTMONT VIEW DIV. 1 VOL 34, PGS 12 & 13 1 6. PLAT OF WESTMONT VIEW DIV. 2 FOUND BRASS CAP IN VOL 36, PGS 24 & 25 CONCRETE MON IN CASE (RMA-4561) 123.42' 7. PLAT OF LORAIN WOODS VOL 5I,PGS 145&146 8. LOT LINE ADJUSTMENT VOL 1480, PG 387 AFN 7903130265 9. LOT LINE ADJUSTMENT VOL 2458, PG 2680 AFN 9107030E40 CERTIFICATE RECORDING CERTIFICATE � FILED FOR RECORD THIS DAY OF THIS MAP CORRECTLY REPRESENTS A SURVEY .:o�wASsl�;l�, }s, AT M. IN BOOK OF MADE BY ME OR UNDER MY DIRECTION IN CON- FORMANCE WITH THE SURVEY RECORDING ACT SURVEY'S AT PAGE AT THE REQUEST AT THE REQUEST OF JOHN THORESEN OF DAVID EVANS AND ASSOCIATES, INC. ECTIONS QN JUNE 29 2000 d•z9Zq SIGNATURE DATE CERTIFICATE N0. 11104 DIVISION OF RECORDS & EL MANAGER/AUDITOR SUPT. OF RECORDS/DEPUTY AUDITOR AF SURVEYOR'S 0 CV .N- INGRESS, EGRESS &UTILITY EASEMENT PER AF# A ON OF THE 804, SW1/4, Sic. 5, T 27 N, R 4 E, W.M. Cn FOUND 1-1/2" BRASS DISK Q0 I IN CONC (IN CASE) �-- BASIS OF BEARING N01'4T58"E 351.43' � 351.05' �M) P) FOUND BRASS � PLUG IN LEAD IN CONC (IN CASE) BASIS OF BEARING THE BEARING N 01'47'58" E AS MEASURED BETWEEN THE FOUND MONUMENTS IN 72ND AVENUE WEST AND SET BY THE PLAT OF WESTMONT VIEW DIV. 1, VOL 34, PGS 12 & 13. LEGEND O INDICATES MONUMENT FOUND BY THIS SURVEY ® INDICATES REBAR &CAP FOUND BY THIS SURVEY O ALL LOT CORNERS ESTABLISHED WITH A 1 /2" DIA. BY 24" LONG REBAR WITH CAP, "DEA 18904". (C) -CALCULATED (M) -MEASURED (P) -PLAT BSBL -BUILDING SETBACK LINE SURVEY NOTES 1. A ONE SECOND THEOLODITE AND ELECTRONIC DISTANCE METER WERE USED FOR THIS SURVEY. 2. THIS SURVEY EXCEEDS THE MINIMUM REQUIRED SURVEY PRECISION FOR FIELD TRAVERSES, AS SET FORTH BY WAC 332-130-090. 3. ALL MONUMENTS FOUND WERE FIELD VISITED IN JUNE 1998. EASEMENT LINE TABLE LINE LENGTH BEARING E1 186.38 N32'39'48"W E2 163.35 N32'39'48"W E3 24.48 N32'39'48"W E4 55.39 N40'28'38"W E5 67.68 N40'28'38"W E6 17.99 N32'39'48"W E7 10.09 N24'33'03"W ES 14.89 S35'44'40"E 9 131.21 N22'47'18"W 0 42.90 N22'47'18"W 1 112.45 S41'30'42"W 2 rEl 129.62 S58'14'38"E 3 20.00 N31'45'22"E 4 92.42 S58'14'38"E E15 99.01 S41'30'42"W E16 51.14 N22'47'18"W E17 145.45 N22'47'18"W E18 126.03 N71'43'10"E EASEMENT CURVE TABLE CURVE LENGTH RADIUS DELTA EC1 13.74 50.00 15'44'45" EC2 37.87 32.00 6T48'12" FILES S-98-108 8c V-98-109 DAVID EVANS AND ASSOCIATES, 04, 1620 W. MARINE VIEW DR. SUITE 200 EVERETT, WA. 98201 (425)259-4099 SHEET 2 SCALE 1"=50' SURVEYED FIELD BOOK _ DRAWN ccw CHECKED RCH FILE THOR0001 OF 2 LEGAL DESCRIPTION LOT "B", OF THE LOT LINE ADJUSTMENT IN THE SNOHOMISH COUNTY RECORDS UNDER AUDITOR'S FILE NO. 9107030640, BEING A PORTION OF LOT 53 AND THE NORTH HALF OF LOT 52, PLAT OF MEADOWDALE BEACH, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 5 OF PLATS, PAGE 38, RECORDS OF SNOHOMISH COUNTY, WASHINGTON. TOGETHER WITH THAT PORTION OF THE SOUTH HALF OF SAID LOT 52 LYING NORTHERLY OF A LINE BEGINNING AT A POINT ON THE EAST LINE OF LOT 52 THAT IS 66.12 FEET NORTH AS MEASURED ALONG SAID EAST LINE FROM THE SOUTHEAST CORNER OF SAID LOT 52; THENCE NORTH 68'03'00" WEST A DISTANCE OF 269.35 FEET TO THE NORTH LINE OF SAID SOUTH HALF AND THE TERMINUS OF THE HEREIN DESCRIBED LINE. SETBACK INFORMATION 1. SETBACKS SHOWN ARE FOR REFERENCE ONLY AND VEST NO RIGHT, 2. MINIMUM 25 FOOT SETBACK BETWEEN STRUCTURES AND TOP OF BANK MUST BE MAINTAINED ON LOTS 1 & 2. 3. MINIMUM 15 FOOT SETBACK BETWEEN STRUCTURES AND TOP OF BANK MUST BE MAINTAINED ON LOTS 3 & 4. 4. AS RECOMMENDED WITHIN THE EIS, A NATIVE GROWTH, NON -DISTURBANCE AREA WITHIN THE 15 FOOT AND 25 FOOT BUILDING SETBACKS FROM THE TOP OF THE BANK SHALL BE ESTABLISHED. 5. THE HEARING EXAMINER HAS GRANTED A SETBACK VARIANCE FOR LOTS 1 & 2. CRI11CAL AREA VARIANCE THE HEARING EXAMINER HAS GRANTED A CRITICAL AREAS VARIANCE AS FOLLOWS: 1) ELIMINATION OF STEEP SLOPE CRITICAL AREA SETBACK AND BUFFER REQUIREMENTS AND 2) REDUCTION OF THE 15 FOOT BUILDING SETBACK FROM THE WETLAND BUFFER FOR LOTS 3 & 4. CONDITIONS COMPLIANCE WITH ALL OF THE CONDITIONS OF APPROVAL FOUND IN THE FINAL APPROVAL OF THE SHORT SUBDIVISION AND THE ATTACHMENTS THERETO. A COPY OF SAID DOCUMENT IS LOCATED IN FILE S 98-108 AND V 98-109 IN THE OFFICE OF THE CITY OF EDMONDS PLANNING DIVISION. DECLARATION WITH THE RECORDING OF THIS SHORT SUBDIVISION THE PRESENT OWNER(S) DECLARE THE PRIVATE EASEMENTS AS SHOWN HEREON AND THAT SAID EASEMENTS ARE TO THE BENEFIT OF THE PRESENT OWNERS, THEIR HEIRS SUCCESSORS, OR ASSIGNS, OF LOTS 1, 2, 3_ AND 4 OF THIS SHORT SUBDIVISION. 20' PRIVATE ACCESS EASEMENT: MAINTENANCE, OPERATION, REPAIR AND/OR RECONSTRUCTION, AS INTENDED IN THIS DECLARATION, APPLY TO ALL NECESSARY MATERIALS AND LABOR REQUIRED TO MAINTAIN A STABLE AND USABLE ROAD SURFACE FOR INGRESS AND EGRESS OF SAID 20' PRIVATE ACCESS AND UTILITY EASEMENT SHOWN ON THIS PLAT AND IDENTIFIED ABOVE. THE COSTS OF SAID MAINTENANCE, OPERATION, REPAIR AND/OR RECONSTRUCTION SHALL ALSO BE BORNE EQUALLY AND JOINTLY BY THE OWNERS, THEIR HEIRS, SUCCESSORS, AND ASSIGNEES OF SAID LOTS 1, 2 AND 3. HOLD HARMLESS OWNER, AND ALL PERSONS HAVING ANY PRESENT, OR SUBSEQUENT, OWNERSHIP INTEREST IN THESE LANDS, AND ANY SUCCESSORS AND ASSIGNS OF OWNERS OR OTHER PARTIES HAVING ANY SAID INTEREST, HEREBY AGREE THAT THE CITY OF EDMONDS SHALL BE HELD HARMLESS IN ALL RESPECTS FROM ANY CLAIMS FOR INJUNCTIVE RELIEF WHICH MAY BE OCCASIONED, NOW OR IN THE FUTURE, TO ADJACENT LAND OR IMPROVE- MENTS BY REASON OF THE CONSTRUCTION, OPERATION AND MAINTENANCE OF THE DRAINAGE SYSTEM AND HEREBY WAIVE AND RELEASE THE CITY OF EDMONDS FROM ANY AND ALL CLAIMS FOR DAMAGES, EXCLUDING DAMAGE SOLELY CAUSED BY AN ACT OR OMISSION OF SAID CITY AND INJUNCTIVE RELIEF WHICH THE OWNERS, OR THEIR SUCCESSORS OR ASSIGNS, MAY THEMSELVES HAVE NOW OR IN THE FUTURE BY REASON OF THE CONSTRUCTION, MAINTENANCE AND OPERATION OF SAID DRAINAGE SYSTEM. NATIVE GROWTH PROTECTION EASEMENT AN EASEMENT IS RESERVED FOR AND GRANTED TO THE CITY OF EDMONDS AND ITS CITIZENS WITHIN THE AREA SHOWN ON THE PLAT AND MARKED NATIVE GROWTH PROTECTION EASEMENT IN ORDER TO PRESERVE THE PHYSICAL AND AESTHETIC CHARACTER OF THE CITY AND PARTICULARLY THE SAFETY AND STABILITY OF STEEP SLOPES AND OTHER CRITICAL AREAS THROUGH THE PREVENTION OF INDISCRIMINATE REMOVAL OR DESTRUCTION OF NATIVE VEGETATIVE GRCWTH ON DEVELOPED OR PARTIALLY DEVELOPED PROPERTY. EXCEPT AS PROVIDED HEREIN, THE OWNERS OF THE PROPERTY SHALL PRESERVE AND MAINTAIN THE EXISTING NATIVE GROWTH AND VEGETATION AND SHALL NOT CUT, PRUNE, LOG, DESTROY BY THE USE OF HERBICIDES OR OTHERWISE DISTURB THE NATIVE GROWTH WITHIN THE EASEMENT EXCEPT THAT DEAD, DYING OR DISEASED VEGETATION MAY BE REMOVED WHICH IS AN UNREASONABLE THREAT TO THE SAFETY OF ANY ADJACENT HOME OR PUBLIC OR PRIVATE RIGHT-OF-WAY OR WHEN NECESSARY TO PROTECT THE REMAINING VEGETATION FROM DISEASE. IN STEEP SLOPE ENVIRONMENTS AND AREAS SUBJECT TO EDMONDS COMMUNITY DEVELOPMENT CODE (ECDC) SECTION 19.05, REQUESTS TO REMOVE VEGETATION OR TREES WHICH MAY INCREASE THE RISK OF SLIDE DANGER SHOULD BE ADDRESSED TO THE CITY ENGINEER FOR ADMINISTRATIVE REVIEW SUBJECT TO ECDC SECTION 18.45.030.G AS SAME EXISTS OR IS HEREAFTER AMENDED. SUCH AREAS MAY BE ALLOWED TO NATURALLY RESEED THEMSELVES UNLESS REPLANTING IS NECESSARY TO PRESERVE SLOPE STABILITY, PRE- SERVE A WATER SHED AND WATER QUALITY, PREVENT EROSION OR WHEN NATIVE GROWTH IS DESTROYED OR DAMAGED BY FIRE OR OTHER NATURAL CATASTROPHE. IN SUCH CASES, REPLANTING SHALL BE UNDERTAKEN AT THE COST OF THE OWNER(S) OF PROPERTIES WITHIN THE SUBDIVIDED TRACT WITH APPROPRIATE NATIVE PLANTS. REPLANTINGS SHALL BE WATERED, MAINTAINED AND REPLACED UNTIL THE DAMAGED AREA HAS BEEN RESTORED. NO HERBICIDE, PESTICIDE OR OTHER CHEMICAL SHALL BE USED IN THE EASEMENT AREA EXCEPT AS MAY BE NECESSARY TO ADDRESS INSECT OR RODENT INFESTATION IN ACCORDANCE WITH LAW OR ADMIN- ISTRATIVE ACTION. 15' PRIVATE STORM AND SANITARY SEWER EASEMENT AND 20' PRIVATE STORM DRAINAGE EASEMENTS: MAINTENANCE, OPERATION, REPAIR AND/OR RECONSTRUCTION, AS INTENDED IN THIS DECLARATION, APPLY TO ALL NECESSARY MATERIALS AND LABOR REQUIRED TO MAINTAIN A STABLE AND USABLE DRAINAGE AND SANITARY SEWER SYSTEM WITHIN THIS PLAT AS SHOWN HEREON AND IDENTIFIED AS THE 15' PRIVATE STORM AND SANITARY SEWER EASEMENT AND THE 20' PRIVATE STORM DRAINAGE EASEMENTS. THE COSTS OF SAID MAINTENANCE OPERATION, REPAIR AND/OR RECONSTRUCTION SHALL ALSO BE BORNE EQUALLY AND JOINTLY BY THE OWNERS, THEIR HEIRS, SUCCESSORS, AND ASSIGNEES OF SAID LOTS 1, 2, 3 AND 4. SURVEYOR'S CERTIFICATE , c:.�� RE+coRc�rl CERTIFICATE THIS MAP CORRECTLY REPRESENTS A SURVEY 4.• •,fir/ FILED FOR RECORD DAY OF MADE BY ME OR UNDER MY DIRECTION IN CON- �'w°� '^>�r�''•- AT M, IN BOOK of FORMANCE WITH THE SURVEY RECORDING ACT �;�� :'� SURVEYS AT PAGE AT THE REQUEST Al' 111117 11rot imi, or Jul IN 111n1W..vZN i�;"' M Or DAVIT? CVANR AND A550GIATrS, INC.. 111 I , 111111 'ill, �11h1�1 of �� 11� �\,�, �A1 I 0.0olA „ 1 I,I i'i4tl•, ,M 111 `II,RI't 1, �t, 1 1 1 I i/,.,„�-�<. �r »•r' a1111 ` �r'I11,+�I, h 1\I,�11 11\II\1�1I/ \I111111u1 Ill�tll�11�t� 11 (11 {� !arilw,+w.,ar Ill'1 i l 111,'„111„ 111'lll, \Illll„1, 1 1 ! I it I1 ,' II I! ► I lulu I 11 . ,,I,ul1 I. " r I CITY OF E N�.?S, _WI _ SHINOTON I/WE VERIFY THAT I/WE ARE THE LEGAL OWNER(S) OF THE PROPERTY DESCRIBED ABOVE AND I/WE CERTIFY THAT THIS SUBDIVISION WITH THE FOLLOWING DEDICATIONS AND CONDITIONS IS MADE OF MY/OUR PUT r..nNSFNT AND ACCORDING TO MY/OUR DESIRES. PROPERTY OWNER SIGNATURE LINES NAME 7er x NAME 121 LIVI R 9 1XIM, ti 1, STATE OF WASHINGTON �SS COUNTY OF I CERTIFY THAT I KNOW OR HAVE SATISFACTORY EVIDENCE THAT IS THE PERSON WHO APPEARED BEFORE ME, AND SAID PERSON ACKNOWLEDGED THAT HE/SHE SIGNED THIS INSTRUMENT AND ACKNOWLEDGED IT TO BE HIS/HER FREE AND VOLUNTARY ACT FOR THE USES AND PURPOSES MENTIONED IN THE INSTRUMENT. DATED SIGNATURE MY APPOINTMENT EXPIRES STATE OF WASHINGTON ISS COUNTY OF I CERTIFY THAT I KNOW OR HAVE SATISFACTORY EVIDENCE THAT IS THE PERSON WHO APPEARED BEFORE ME, AND SAID PERSON ACKNOWLEDGED THAT HE/SHE SIGNED THIS INSTRUMENT AND ACKNOWLEDGED IT TO BE HIS/HER FREE AND VOLUNTARY ACT FOR THE USES AND PURPOSES MENTIONED IN THE INSTRUMENT. DATED SIGNATURE MY APPOINTMENT EXPIRES APPROVALS APPROVED AND AUTHORIZED FOR RECORDING BY THE CITY OF EDMONDS ENGINEERING DIVISION BY: 1 `rLE C4-jIZt-to l-ltaI`F THIS Z!� DAY OF Aw(^f-NsT2000- APPROVED AND AUTHORIZED FOR RECORDING BY THE CITY OF EDMONDS PLANNING DIVISION BY: 4� st4- .,1, " THIS3I-DAY OF +dµ��2000. A I'N N 11 k.W c.W1 I I A"' l"1WI/A SWI/A Sm', 5, T 27 fib 1114 E, WAL FILES S-98-108 & V-98-109 DAVID EVANS Pr11IT-T��'' AND ASSOCIATES, t 0_'tl 11'. 11A INN VIEW I)IK. SUITE �00 ItiVERE"I"I'. IVA. 98201 (425)259-4099 SHEET 1 OF 2 SCALE 1"=50' Kc0- 7*91 FIELD BOOK DRAWN GGw CHECKED RCH FILE THOROOOI -5-e,vu,olA Z1,06tf YX'40,7 - /�� j, ,!��.m -mcy 57 LEGAL DESCRIPTION (PLAT) THAT PORTION OF THE SOUTHWEST QUARTER OF THE SOUTHWEST QUARTER OF SECTION 5, TOWNSHIP 27 NORTH, RANGE 4 EAST, W.M., MORE PARTICULARLY DESCRIBED AS FOLLOWS: LOT "B", OF THE LOT LINE ADJUSTMENT IN THE SNOHOMISH COUNTY RECORDS UNDER AUDITOR'S FILE NO. 9107030640, BEING A PORTION OF LOT 53 AND THE NORTH HALF OF LOT 52, PLAT OF MEADOWDALE BEACH, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 5 OF PLATS, PAGE 38, RECORDS OF SNOHOMISH COUNTY, WASHINGTON. TOGETHER WITH THAT PORTION OF THE SOUTH HALF OF SAID LOT 52 LYING NORTHERLY OF A LINE BEGINNING AT A POINT ON THE EAST LINE OF LOT 52 THAT IS 66.12 FEET NORTH AS MEASURED ALONG SAID EAST LINE FROM THE SOUTHEAST CORNER OF SAID LOT 52; THENCE NORTH 68'03'00" WEST A DISTANCE OF 269.35 FEET TO THE NORTH LINE OF SAID SOUTH HALF AND THE TERMINUS OF THE HEREIN DESCRIBED LINE. PORTION 17 4 E7 Wm LORIAN WOODS VOL. 51. PGS. 145 & 146 cc 64 03 \27, 22 F \ \ -100 \ \ \ \ \ 000, \ \ 40 00 co / ` + L 2 I 00 w s\\ \ �� \ \\ \ �\ \ I N \✓ \ / �. \ \ \ \ 4� 892 SF \ AN / `oo'40, \ ?> CV w 40 _ 1 N u� I / ^ \\� \ \ \\\\ 1� \\�' Yam_ N / o 122.07 cd N89 38 04 W JOHN L. JOINSON \ INGRESS, EGRESS & \ \ \ U11UTY EASEMENT \ JEANINE L. CASPER GREGORY S. CASPER IACINf Y MAP SCiALE•. 1'-1000' DEVELOPER JOHN THORESEN 1 /4'Lz/- 4187;u ?4 w• EDMONDS, WASHINGTON 98026 TELEPHONE: (425) 745-t587 Va Y- 3-lte9 ENGNEER/PREPARER DAVID EVANS AND ASSOCIATES, INC. 1620 W. MARINE VIEW DRIVE SUITE 200 EVERETT, WASHINGTON 98201 TELEPHONE: (425) _259-4099 _ -- FAX: (425) 259-3230 CONTACT PERSON: JACK N. MOLVER, P.E. DATUM AND BENCHMARK DATA VERTICAL DATUM: CITY OF EDMONDS BENCH MARK INVERT ELEVATION'OF EXISTING 8" PIPE IN SANITARY SEWER MANHOLE IN N. MEADOWDALE ROAD. 45t FEET NORTH OF THE N.W. PROPERTY CORNER. ELEVATION = 143.09 RECEIVED DEC 2 7 1999 PERMIT COUNTER P. bd V2 O w a s;y 0 0 N N J W a w CD CA C�2 o ��Kr H rn Lo CQ P4 CQ o rn = rn V) rn r- Q O z H U � A 0 po ceo,14 /6i"5 FILE RIECiElVIED MAR 2,8 2000 DEVELOPMENT SERVICES CTR. )f CITY (F EDMONDS LEGAL DESCRIPTION PLAT THAT PORTION OF THE SOUTHWEST QUARTER OF THE SOUTHWEST QUARTER OF SECTION 5, TOWNSHIP 27 NORTH, RANGE 4 EAST, W.M.I MORE PARTICULARLY DESCRIBED AS FOLLOWS: LOT "B", OF THE LOT LINE ADJUSTMENT IN THE SNOHOMISH COUNTY RECORDS UNDER AUDITOR'S FILE NO. 9107030640. BEING A PORTION OF LOT 53 AND THE NORTH HALF OF LOT 52, PLAT OF MEADOWDALE BEACH, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 5 OF PLATS, PAGE 38, RECORDS OF SNOH MISH COUNTY, WASHINGTON. TOGETHER WITH THAT PORTION OF THE SOUTH HALF{ 0�' SAID LOT 52 LYING NORTHERLY OF A LINE BEGINNING AT A POINT ON THE EAST LINE"lOF LOT 52 THAT IS 66.12 FEET NORTH AS MEASURED ALONG SAID EAST LINE FROM THE SOUTHEAST CORNER OF SAID LOT 52; THENCE NORTH 68'03'00" WEST A DISTANCE OF 269.39 FEET TO THE NORTH LINE OF SAID SOUTH HALF AND THE TERMINUS OF THE HEREIN DESCRIBED LINE. SHEET INDEX 1 COVER SHEET 2 CLEARING, GRADING AND TESC PLAN iu 3 CLEARING, GRADING AND TESC NOTES AND DETAILS !ij 4 STORM DRAINAGE AND UTILITY PLAN !) 5 STORM DRAINAGE AND UTILITY NOTES AND DETAILS I' 6 DRIVEWAY PROFILE AND DETAILS nr:c. A PORTION. OF THE SW 1/4-7 SECTION 57 T 27 N 7 R 4 E, Wivi LORIAN WOODS VOL. 51, PGS. 145 do 146 i i i i I i I N / z / JEANINE L. CASPER W 126 9*--- Z- kx jAz JOHN L J01IN:ON \ INGRESS, I€GRESS &— hrfc \ \ U11U� E SEMt 50,' —1J1 z v CH LUrd� GUL17 1 156TH ST SW — i L-L z a � I 160TH ST SW o to 00 CD w Q I a �161ST t • N 164TH Si SW I- -- 164111 lz R a� PROJECT SITE oio I �:I: Fla DEVELOPER JOHN THORESEN 15621 48IH PLACE W. EDMONDS, WASHINGTON 98026 TELEPHONE: (425) 424-3049 ENGINEER/PREPARER DAVID EVANS AND ASSOCIATES, INC. 1620 W. MARINE VIEW DRIVE SUITE 200 EVERETT, WASHINGTON 98201 TELEPHONE: (425) 259-4099 FAY,: (425) 259-3230 C014TACT PERSON: JACK N. MOLVER, P.E. DATUM AND BENCHMARK DATA VERTICAL DATUM: CITY OF EDMONDS BENCH MARK INVERT ELEVA IION OF EXISTING 8" PIPE IN SANITARY SEWER MANHOLE IN N. MEADOWDALE ROAD, 45± FEET NORTH OF THE N.W. PROPERTY CORNER. ELEVATION - 143.09 a� l�sy4 IN w { w h�Y Y f N to N N �pw ! 10 CQ U) L W q "a; w E, OW �+ t ? q to w A a 0 GREGORY S. CASPER ai t� � 7U.• WESTMONT VIEW DIV. 2 8 VOL. 36, PG. 25 APPFl D FOR CONSTRUCTION I s ' /30 0J I IIY or EDMUNDs f DALE • .1 A PORTION Cf _ THE -E SW1 /41 SECTION � CN 5 T. 27 N., R. 4E., W.M. 0 15 30 607Z -- / 12nd AVENUE / W SF 1 SCHEDULE AND ATTEND PRECONSTRUCTION MEETING WITH CITY OF EDMONDS. \ �., / y` / �•� SNOT OPEN) s s / / / / // 3 / // / ,c� 5, 71l _ r �j� - sD� ___—__CI�9 _ , su _ - _ — - so --- — �_-- -- - --- ry, fir/ I PIPES, DETENTION PIPE AND PAVED — �` ss 5 STORM DRAINAGE STRUCTURES, �r-/-s$ --- — ss- '� ----------Ss -- / / / / / TALL / � / / / / / ,--TOP I DF �-�— U2 INS ACCESS ROAD PER PLAN SHEET 4 OF 6• W.D.F.W. SHALL BE OBTAINED _ 375.26 / / / N 7'58" / / / / / / � A I r �-�'`q HYDRAULIC PROJECT APPROVAL E(HPA) FROM 24.68' 162.32 " \ / / � A HYD % FOR ACCESS ROAD STREAM CROSSING CONSTRUCTION. \ �, 188.26 / LIMI i OF 2CEARIN� �o� /�,�� CLEARING LIMITS WHERE SHOWN.�j &RAD�NG/(TfP) 6 / / / ��Q,• / N / TALL SILT FENCE ALONG STREAM AND ALONG CL TREES. / n c{- -�- - - - - - - - - - -- / 3C INS - - / NO MACHINE CLEARING ALLOWED MEANDER AROUND SIGNIFICANT TR V / \ �\ \ r - i �` �c,''-/% �'� 7 ' J // 7` / AJ�'/ >[ / N PER DETAIL 3, SHEET 3 OF 6. /-s� ENT TRAP WHER SHOW 4 CONSTRUCT SEDIMENT ' eF /j v\ 5 CONSTRUCT TRENCH BEHIND SILT, ENCE WHERE SHOWN PER DETAIL 4, SHEET 3 OF 6. \ i / \\ / ' I I /1 / / / / O I / �t WITHIN SPECIFIED LIMITS.1 S OCKPILE TOPSOIL IN DESIGNATED AREA AND `� / 6 CLEAR O TIC SHEATHING.'! / //� I I I I/ / / / / / COVER WITH PLASTIC \ 1 \ l / I / / OWNER. / / � / / ' • �� / I I� � 7 RELOCATE EXISTING GARDEN SHED AT DIRECTION OF ADJOINING / ' I O � � SHEET 3 OF 6. ONSTRUCTION ENTRANCE WHERE SHOWN PER DETAIL 1, S GARAGE I I ZED C r / / / / 8C INSTALL STABILIZED / _ / 1 \ I \ /f 10 NSTRUCTION FROM DESIGNATED AREA. r, �• ,/-'' / / \ I \ / 1 ow '�' / ,I / 34 052 NSF / ) INGRE q, EGRESS dcl PILE AND STAGE CO t� r; / O \ I / �41 �f'~-J= / UTILIT EASEMENT 1 9C STOCK I ;! /--� a �w // �\ \ I / 1/z / 1 / / ' t / 1 2 AND 3. '/� / / cn / / f " = 10 ROUGH GRADE DRIVEWAY AND LOTS r �gaJ� // I \ / \ m / °0 / _ / 8 I AND RAD, A TIME OF HOUSE CONSTRUCTION. I ( ml ��' / ALL BE CLEARED LOT I / / / / / // ,/ f I \ / \ Y OR BLOCK WALLS (KEYSTONE OR EQUAL) PER GEOTECIINICAL � / ° / �'� L ROCKER _ / 11 INSTAL MANUFACTURES SPECIFICATIONS.8,892 SF/'• / �=�>: 7 � O ENGINEERS RECOMMENDATIONS (AND/OR M / ' \ / \ /4 r,Q )/ / / I i % .� �S• / / / \ / � / / 1�y 'OF / -� •� 1, / �\ VIA 12 INSTALL UNDERGROUND UTILITIES / / / // / I / l / \ �.\ / / , GARAGE / EXPOSE SOILS EXCEPT DRIVEWAYS. -�- / / Z • \ / / / I / { I/ i �'01� 13 MULCH AND HYDROSEED E \/ / / (i i=8, i / , \ AND PAVE DRIVEWAYS. yr��` / � ll 14 FINE GRADE _ BE SEVERED AND ABANDONED.___ % / / / / \ � \ i / / / / / aH s ON SYSTEM TO o• - / --- 15 EXISTING IRRIGATION •-./ / / \ / / / i \/ ,\ /aH= 03 LEGEND ` A. = HEIGHT OF ROCKERY--=�G'F�'T��-�-� ly'� ,='�'/��5� \ / / / / `� \ / i / Rh L, . i/ \ �°'/// I \ / / / \ / ; % 4� /� \\ 7 / \/ / �g // % Ex Hausa % SF =SILT FENCE PER DETAIL 2, SHEET 3 5' 49, 221 SY \/If STOCKPILE &9 CONSTRUCTION �\ / - 2 / �~ /~�� \ % I \' / LIMIT OF•�CLEARItJG 1,� /k" '� � a� � � 11 � 15 STAGING AREA /\ O & GRAISING (TYP) �- / `/ l r I I 1 \ I �I 1101'17'36"E (TYP) 0 / -z- l \ ��;t / SF / \ C` / C I� \\ 58.7I 00 �10 ` -3 5- ,/ \ RH- '�-:Amvy 0 �QI�I"\/ /.• j� / l yp l —j., Ir .g \ \I� 17.5' 0(,� 0 f� / - / ��1yY \ / y f1<C� 11,EI— c.GF �\ n ' N � l�rl 1 ••2_ II '71 221.86' 499.17 X \T A' /o of ,. LIMIT OF CLEAR( / E; nr v �' I cv �►�' j / �N�Z s & GRADING (TYP) Q' ��/---------------- --24�� { yYr't� - TOP OF r ter; pF BANK N �C lkvyl\ 153.89' 123.42' N01'17'36"E SOIL ST/�®ILIZAT1014 NOTE SC MINIMUM REQUIREMENT - STABILIZATION OF EXPOSED AREAS ALL SOILS EXPOSED BY LAND DISTURBING ACTIVITIES SHALL BE STA91LIZIED BY SUITABLE APPLICATION OF BMP'S, INCI.UDING, BUT NOT LIMITED TO, SOD, HYDROSEEDING, OR OTHER VEGETATION, PLASMIC COVERING OR MULCHING. ALL BMP'S SHALL BE SELECTED, DESIGNED, AND MAINTAINED IN ACCORDANCE WITH THE MANUAL. THE EXPOSED SOILS SHALL BE HALBILIZEDD ACCORDING TO AN APPROVED TIMETABLE. (TYPICALLY, NO SOILS FOR MORE THAN TWO (2) DDAYSF NO MORE THAN SEVEN (7) ROM FROMOCTAM g1 RTI IROUGIOI SEP (EMBER 3) D APPROVED FOFU J >� CITY OF EDMONDS ENGINEER I CLEARING AND GRADING ATE z 0 Q z A z 0 2 fn LIM N {' U � �.t fYN Ad+ U1 pq U� � , co LJ) A wN A r W � o� A ;° w w 3` v.l ZI VI z L O A 0 0 0 II p 0 z C w H C Q UU] p A. PORTION OF THE SW QUARTER, SECTION T2�N, RZIL.., WM R SiTE QlADING AND T.E,S.U. NOTES I I 1, Non-compliance with the erosion control requirements, water quality requirements and clearing limits violations may result in revocation of project permits, plan approval and bond foreclosures. f 2. Prior to any site construction to include clearing/logging .or gradin the site/lot clearing limits shall be located and field identified by the project.Isurveyor engineer as required by these plans. Tlie project surveyor/engineer's name; and telephone number is David Evans and Associates, Inc. (425)259-4099. s Engineer eer to the it of Ed monds E 3. Prior to any site work, the contractor shop contact y 9 schedule a preconstruction conference. Due to field changes (revisions), engineered as-builts shall be required prior to site approval. 4. The temporary erosion/sedimentation control facility shall be constructed prior to any grading or extensive land clearing in accordance with the, approved temporary erosion /sedimentotion control plan. These facilities must be satisfactorily maintained until construction and landscaping is completed and the., potential for on -site erosion has passed. 5. All site work must comply to Chapter 33 of the Uniform Building Code (latest edition). 6. All earth work shall be performed mil accordance with city standards. 7. If cut and fill slopes exceed a maximum of two feet horizontal to one foot vertical, a rock or concrete retaining wall may be required. All rock retaining walls greater than eight (8) feet in height are to follow city specifications and to be designed and certified b a civil engineer experienced in soils mechanics (see Soiisl Report for recommend atIons�. 8. Stockpiles are to be located in safe areas and adequately protected by temporary seeding and mulching. HYDROSEED preferred. I ;I 9. All earthwork and construction related activities shall be per the recommendations outlined in the Geotechnical engineers soils report. I 'I 10. The Geotechnical engineer shall examine all stripped subgrade areas and approve rolling operations prior to the start of fill placement or earthwork. Stripping depth shall be established by the Geotechnical engineer. 11. The Geotechnical engineer shall perform field density test ng of structural fills as needed during placement and observe the grading and earthworm, operation. FILTER FENCE 1. The filter fabric shall be purchased in a continuous roll lut to the length of the barrier to avoid use of joints. When joints are necessary, filter' cloth shall be spliced together only at a support post, with a minimum 6 inch overlap, and both ends securely fastened to the post. I 2. Posts shall be spaced a maximum of 6 feet apart andtr riven securely into the ground a minimum of 30 inches (where physically possible). I 'I) 3. A trench shall be excavated approximately 8 inches wide and 12 inches deep along the line of posts and upslope from the barrier. The trench shall be constructed to follow the contour. i i 4. When slit film filter fabric is used, a wire mesh support fence shall be fastened securely to the upslope side of the posts using heavy-duty wire staples at least 1 Inch long, tie wires or hog rings. The wire shall extend into the trench a minimum of 4 inches and shall not extend more than 36 inches above the original ground surface. 5. Silt film filter fabric shall be wired to the fence, and 20 inches of the fabric shall extend. into the trench. The fabric shall not extend more (lion 36 inches above the original ground surface. Filter fabric shall not be stapled to existing trees. Other types of fabric may be stapled to the fence. 6. When extra -strength or monofilament fabric and closer post spacing are used, the wire mesh support fence may be eliminated. In such a case, the filter fabric is stapled or wired directly to the posts with all other provisions of Filter Fence Note 5 applying. Extra care should be used when joining or overlapping these stiffer fabrics. 7. Local governments may specify the use of properly c,m acted native material. in many Instances, this may be the preferred alternative becaus the soil forms a more continuous contact with the trench below, and use of native mate. a cuts down on the number of trips that must be made on and off -site. If gravel Is used instead, the trench shall be backfilled with 3/4-inch minimum diameter washed gra el. Care must be taken when using gravel to ensure good contact between the fabric and the trench bottom to prevent undercutting. 8. Filter fabric fences shall be removed when they have served their useful purpose, but not before the upslope area has been permanently stabilized. Retained sediment must be removed and properly disposed of, or mulched and seeded. Filter Fence Maintenance iii 9. Inspect immediately after each rainfall, and at least daily during prolonged rainfall. Repair as necessary. I , 10. Sediment must be removed when it reaches approximat ly one third the height of the fence, especially If heavy rains are expected. 11. Any sediment deposits remaining In place after the filte fence is no longer required shall be dressed to conform with the existing grade, prepared and seeded. 12. All temporary erosion and sediment control measures sall be removed within 30 days after final site stabilization is achieved or after the lemporary Best Management Practices are no longer needed. Trapped sediment shall be reinoved or stabilized on site. Disturbed soil areas resulting from removal shall be permanently stabilized. I TEMPOWT (NAVEL CON91fiUC'110N ENIMCE 1. AGGREGATE: Ballast (WASH DOT std. spec. 9-03.9(1). i 2. ENTRANCE DIMENSIONS: The aggregate layer must be at least six (6) inches thick. It must extend the full width of the vehicular ingress and egress area. Tile length of the .entrance must be at least 100 feet. I 3. WASHING: If conditions on the site are such that i most of the mud is not removed from vehicle tires by contact with the gravel, then the ,tires must be washed before vehicles enter a public road. Wash water must be carried; away from the entrance to a settling area to remove sediment. A wash rack may also be used to make washing more convenient and effective. j 4. INSTALLATION: The area of the entrance should be cleared of all vegetation, roots and other objectionable material. Tlie gravel shall be placed to the specified dimensions. Any drainage facilities required because of washing should be constructed according to local government specifications. If wash racks are used, they should be installed according to manufacturer's specifications. 5. MAINTENANCE: The entrance shall be maintained in a condition which will prevent tracking or flow of mud onto public rights -of -way. This may require periodic top dressing with 2" stone, as conditions demand. Mud dropped, washed, or tracked from vehicles onto roadway or into storm drains must be removed immediately. HYDROSEEDiNG 1. CONSTRUCTION ACCEPTANCE: Will be subject to a well -established groundcover that fulfills the requirement of the approved construction plans. 2. All disturbed areas such as retention facilities, roadway back . slopes, etc. shall be seeded with a perennial ground cover grass to minimize erosion. Grass seeding will be done using an approved HYDROSEEDER or as otherwise approved by the City of Edmonds. 3. PREPARATION OF SURFACE: All areas to be seeded shall be cultivated to the satisfaction of the county inspector. This may be accomplished by dicing, raking, harrowing or other acceptable means. 4. Immediately following finish grading, permanent vegetation (consisting of rapid persistent and legume) will be applied (minimum 80# per acre). This is to include the following: 20% annual, perennial or hybrid rye grass, 40% Creeping Red Fescue, 40% White Clover. HYDROSEED required. 5. FERTILIZER: Shall be applied at 400# per acre of 10-20-20 (10 pounds per 1100 square feet) or equivalent. TEMP onAfiY_COVEii FnACI10ES= 1. Disturbed areas which are to remain without permanent cover for more than 30 days, shall be stabilized by providing temporary seeding, mulching, matting, or clear plastic covering as a guard against erosion. TEMPOWI SEEDING OF 81111PPED AFIEAS* 1. Planting done in the months of July and August may require irrigation. Planting done between November 1 and March 31 will require mulching immediately after planting. 2. Seed bed should be firm with fairly fine surface. Perform all cultural operations across or at right angles to the slope. 3. Fertilize as per suppliers and/or Soil Conservation Service recommendations. Only Non -Phosphorus fertilizer shall be applied. i 4. The following seed mixture applied at a rate of 120 Ibs/acre or other mixtures and application rates approved in advance by the City of Edmonds shall be used: Porportion Percent Percent Name By Weight Purity Germination Redtop (Agrositis Alba) 107 92% 90% Annual Rye (Loliurn Multiflorum) 40�.' 98% 90% Chewing Fesque (Festuca Rubro Commutate) 40% 97% 80% (Jamestown, Banner, Shadow, or Koket) White Dutch Clover 10� 96� 90� 5. Hydroseeding with approved seed -mulch -fertilizer mixtures may also be used. 6. Seeding shall be supplied with additional moisture as needed, at rates which are controlled to prevent runoff. 1 7. Areas which fail to establish vegetative cover adequate to prevent erosion shall be re -seeded as soon as such areas are identified. MULCHING AND MATT INCH ; 1. Mulch materials, application rates, and specifications, shall conform to the DOE Stormwater Management Manual for the Puget Sound Basin, and shall be approved by the City of Edmonds in advance of use. i 2. Erosion blankets and matting shall conform to and be installed per the DOE Stormwater Management Manual for the Puget Sound Basin, and shall be approved by the City of Edmonds in advance of use. CLEAn PLASTIC COVE [IN 1. Clear Plastic coverings shall have a minimum thickness of. 6 mil and meet the requirements of WSDOT/APWA Section 9-14I5. 2. Covering shall be installed and maintained tightly in place by using sandbags or tires on ropes with a maximum 10 foot grid spacing in all directions. All seams shall be taped or weighted down full length and there shall be at least a 1 to 2 foot overlap of all seams. Seams should then be rolled and staked or tied. 3. Covering shall be installed immediately on areas seeded between November 1 to March 30 and remain until vegetation is firmly established. I 4. When the covering is used on unseeded slopes, it shall be left in place until the next seeding period. 5. Sheeting should be toed In at the top of the slope to prevent surface flow beneath the plastc. 6. Sheeting should be removed as soon as is,possible once vegetation is well established to prevent burning the vegetation. 7. Check Sheeting regularly for rips and places where the plastic may be dislodged. Contact between the plastic and the ground should always be maintained. Any air bubbles found should be removed immediately or the plastic may rip during the next windy period. Re -anchor or replace the plastic as necessary. I INFLOW � QoPo 1 5 �dobc a R=25' (OPTIONAL) 12" MIN. 4"-8" QUARRY SPALLS �yyg � �f,�ypG�pFo `rFa �s ' `roil DETAIL - TEMPORARY CONSTn C HiON ENTRANCE NO SCALE �.,.. OW 1Y ,FILTER FABRIC FENCE RIP -RAP PAD iv OVERFLOW DEPTH 1' DEPTH OF 2" - 4" ROCK 6.0' MIN OVERFLOW CIiAII14EL IS CONSTRUCTED BY EXCAVATION 2' SETTLING DEPTH FILTER �k - r. : �::. j _.� �.,1= ' `• _ _ �_ _ FABRIC LEVEL BOTTOM 1.5' SEDIMENT STORAGE FENCE ELEVATION PER PLAN 1' DEPTH OF 3/4" 10 1 1/2" WASHED GRAVEL NOTE: MAY BE CONSTRUCTED BY EXCAVATION OR BUILDING A BERM MOSS C� T UN 1' DEPTH OF? - 4" ROCK 1' DEPTH OF 3/4" - 1 1/2" WASHED GRAVEL CRAP QUILET DETAIL - SEDIMENT NO SCALE STAPLES OR WIRE RINGS (TYP.) FILTER FABRIC MATERIAL MIRAFI iOOX OR EQUAL. 2"X2" WOOD POSTS, STANDARD OR BETTER OR EQU IVALENT BURY BOTTOM OF FILTER FABRIC MATERIAL IN 8"X12" TRENCH GRADED AREA FILTER FABRIC MATERIAL -, WIRE MESH SUPPORT FNECE FOR FILTER FABRIC _ PROVIDE WASIIED GRAVEL OR COMPACTED NA11VE SOIL AS DIRECTED BY LOCAL Illl IIlIIEi GOVERNMENT N IIII 2"X2"X14GA, WELDED WIRE MESH OR EQUAL �o " CV _ O =110 1 III= i ._lur iu -1111' 111 i i tO 1 C\I I- 6' MAX _I Imo---• CLEARING LIMITS If co 0 . o I - III to �o '� CV DETAIL - SiLT FENCE NO SCALE NEWLY GRADED OR DISTURBED SILT FENCE SIDE SLOPE. 2.00' .. 2.00' TRENCH BACKFILL WITH COMPACTED NATIVE MATERIAL. Ilili.11 _ 111I- � IrlL=fii-IL- - - il-i l l.. ? F. f I j=iij-iie l l-Ill-111-_ -11itt,I]1ITiI_LIiLl I lihf ililfLlil�jill�li rr Ir rr rr V NOTE: INSTALL 111E SILT FENCE FIRST. AFTER THE SILT FENCE HAS BEEN INSTALLED, CONSTRUCT BERM AND TRENCH. /� DETAIL - SILT FENCE W @ERM AND TRENCH 4 NO SCALE PROVED FOR CLEARING AND GRADING CITY -OF EDMONDS ENGINEER DATE J iGl LU ( O U1 V OSum Q (1) ge W �'• INOM W% �h �♦ ph d a sun� 16U 0 X. go Z .a. Ic gig 11111 Q 4�1 i ir 0 15 30 60 CONSTRUCTION NOTES O1 CONSTRUCT PAVED EMERGENCY VEHICLE TURN-AROUNDAT EXISTING PUBLIC ROAD END PER CITY OF EDMONDS STANDARDS. �2 MATCH EXISTING PAVEMENT EDGE AND ELEVATION. O INSTALL STORM DRAINAGE DETENTION VALFROM W.D,F W.RSHALLI BE 5, SHEET 5 OF OBTAINED FOR A HYDRAULIC PROJECT APPROVAL CONSTRUCTION WITHIN THE STREAM. I O RESTORE STREET PER CITY OF EDMONDS STANDARDS. OWATER SERVICE TO LOT 4 TO BE INSTALLED BY CITY OF EDMONDS FORCES AT TIME OF HOUSE CONSTRUCTION. O6 PAVED ACCESS ROAD TO BE USED AS FUTURE DRIVEWAY AND TURNAROUND FOR LOT 4. O RESTORE GROUND TO PRECONSTRUCTION ELEVATIONS. O INSTALL W.S.D.O.T. STANDARD BEAM GUARDRAIL. U9 INSTALL FIRE DEPT. AND EMERGENCY NCY AID ADDRESS SIGNS FOR LOTS 1, 2 AND 3 WHERE I 10 CLEAR VEGETATION WITHIN RIGHT-OF-WAY AS NECESSARY TO EXISTING FIYDRANT- MAXIMIZE SIGHT i 11 PROVIDE 1OLF-18" STEEL SLEEVE FOR STORM PIPE UNDER ROCKERY. 12 CONSTRUCT ROCKERY PER DESIGN BY WM. CHENG, P.E. CgTClLE1I�SIIJ DATED APRIL 20, 2000. TOP 202,08 { SS MAIJHL.E O 10OP 2000. IE 192.09-814 IE 192.04-8"E IE 191.94-f3"W f TOP 197.71 ram% WATER MANHOLE (Pr:V) G I A PORTION OF THE SW1/4,, SECTION 52 T. 27 N., R. 4 E., W.M. CA1CH_E3.CSIN -<� SS 314.OLF I0P 225.60 a - IE 8-80 C'A1CI-1 BASItd _ \ r� 1 _TUP.._3 13. $1 CATCI'1 BASIN ;-.. .. 'top 302.4.7 - �(TI_ ASIN lot, 2.24.34 / , TUI 2.-1.�� ; MANIIDLE_-- IE 218.24--8" 1 tP .303.59 CA1Cl•1-BASIN _____ Sy zz EXPOSED I'Z" Chip i! 29G,24-•8" TOP 229.3�) _CATCI-I_HA5_IW. i CAJLO, 8A5lIJ- 1OP '215.19 \ / 5�- -�-'� "• G ---SS jam ' / /� .�� // .�'� \, � 72nd AVENUE / W 101' 7.21.62 ______ . / p 218.89 / � � � /'' � �1_ �%/ / \ / (NOT OPEN) / SD r ss- -`� I , �2" BLOIA-0FF�5SEMBLY /�_ __ cpd-_ (�*�t- - / -�:_ ¢Li'__._..-_._ ---I� --__ _ l-� SU - `\ -___-�.._ - _40�- 1-8", O'LUG o // >� `- -_/ / / I1 THRUST LtSCKING SS MAt1tI0LE � � / % /TOP 9r BANK / i��`70t/P 8"DI CL5; IE 209.52-8' / OFw. CA Cl lUP 215.40 611 `, t If 4Y'IN� �2� �' CONNECT TO EX 8"DIWM I / / / / '` ��• / �/ I -REMOVE EXISTING PLUG /� ` / �-- / • '"� / / / f I / / ,F Iwlf, . / '--j,� li c,(i &� THRUST BLOCKING V ' I / �� / / / f ' % / / /30 /i1/ 1-8' GAZE VALVE (MJxFL) �� _ R METER do 11 2" WATER SERVICE / /% / f / / / / / :' / 1 3 WAIE / / / / 1 1 LINES IN COMMON TRENCH WIOTL LOTS WIRE PER CITY STANDARDS T i-WATER METER BOX FOR BLOW -OFF VENT 1� %YI O / 1 GARAGE i k t EGRESS &1 n U11LIT SEASEMENf 1 / / zr� it / \ 7 / � / f \ � / / / / � � •.�'�" ti tom' - (l � � ,. � MIDI, ! GARAGE 1 7 r2�' la'H IV to /\ % / /IE=2,• 1.50 4+4 m r JI 7 CB A L TYPE Icc) / 2()' 3% D I l / r� �! / /\ / / / %� "GRAB =z1.00 6. CONSIRUCT OVER EX 8"SS r /o�' ;' / / / / RIM 183.50t a / « / / I EX, HOUSE ` IE=173.20-EX 8"E,W IE=173.37-NEW 6"S c2 C_B B-2�YPE 2 48"0 l / -ti W SOLIO LOCKING COVE '� �/� '1' 2 / / S MH 3 PR SATE J3+49 RIM=1RIM=182.00 .18 - 12"S,E,W - J /; �Vo / W 9NLET PR IEC110 5 \ / / IM=260.0 I CB_B-3 TYPE 1 \ � �'' / IEV179.00 / ,1�=250.00/ / J � � / � ' / \ 10 fNS1ALL AT END OF 12"C �. „ / SUM1� A-6 TYPE 5 4 , A / CB A-3 PE 2 48"0 i W- LOW COh �ROL I UC1lJRE 5 ___ _ 1 4 / % I GRATE--259.50 u ) I GRAZE-175.9 S M / - 12" NEW & EX 6+ ,r / _ IE=245.00-12"1J IE-172.91 __ Jr..=172.91' l":PL `S'o� C /� r f 1 / IE.=25?y50-12"S - / 8 C A TC:Ii BASIN ,� g o / 151.E -12" D / % fin\ / CB �4 TYPE {LING COVEit L' J/ fOP 171.9b1 / S=3a.13% r f LID LOCKING 12 / I I e O -'. Ca1G1'I ElA51IJ .__.- \� i IoLF 12"CMP _ Ss f• 5 2+4 � 175.31 ~� ` f �1S=1�o0% / 6" SS 0 �r 0 lOP=23 .00 / cA 1Q 9rlslt� �' F , .. 6" , ss co �b+5 _ \ IE 224. TCP 171.90 �, \ % �� c�' a . \/ TOp=184. 0 \ / \ .001 9\ / IE= Loa .aI CP IE=173. 6"N,S Ltr'alq�.. \ \ \ I 17.5' i \� / �/ / 2G'G:�ny st \� O ..� p / � 'T = -fi � m / I �ft''' [Yl• 1 1; •A I \ \ C_AT'Cf 1 LIP.51N / 7, �3 w'' / �� f /� ': % / - -TG11' I67.16 i / i / - �� i % r cf �� u -- / 0-72"_fdP / 9 �{. •;12yF� '' .; ��P`�0 ZL� �-,- / -I- ( D 1E 11014 PIPE ' 5 / ` E {� r. '�N� / 7. �C y 14y��t � obo 6 �0�� `\ r�'n� / 1�Z'� 11>)47 l Pr 4 1'II,��' / ` "[IF - \ \ \ 26 STOR , DRAINAGC� �.g• ///'EASFM�tJIE=158.90 fC•F c�/ J�Q�� CATCH EIASIN•_ `\'/ /° 'k // l i //l 7 / �:��, 4Q, �1 0 TOP 1506 �.11TC1'I BASIN__-\ \ \, ,� %(�% T / �\/ �, i ° �s��, "' .r• I OP 151.15 % /�/ / T}„ 4L , IE=145.59 (CP IC '143.09-•8"E I1 1 -13.39- 8" SW N0. 7=--TOP 0� BANK CB A-7 TYPE 2 54" 0 W SOLID LOCKING COVER r' RIM=181.50 \ o , 4' I I �i � F 1 i RIM-226.00 IE= 218.00 I- - L, ze' cf' 7Yldvt� TOP OF BANK y � Ln N 72ND AVENUE W I LENGTH VARIES �I a a UI I SAWCUT NEAT EDGE 2" COMP. DEPTH CLASS 'B' ASPHALT 2" COMP. DEPTH CR. SURFACING TOP COURSE 4" COMP. DEPTIT CR. SURFACING BASE COURSE (BASE APPROVED BY ENGINEER AND GEOIECFI) 2' MIN w Z 3 EXTRUDED CURB (TYP) PER DETAIL 1, SHEET 5 I 2 1 EXISTING GRADE APPROVED SUBBASE CI iY OF EDMONDS ENGINIELK NU Sk;ALt CONSTRUCTION DATE I " ' cd Z � a CL °' a� <..• s't ` rl i *�'•I ' �[ E- m 1{1;t. 'AU,Tft,, Ir.V> V, f W Pq F o wcc 7 O' r7 W �r U) p WE- R C Y Q4 G A a a 0 5 0 . j a O N O t MI w 0 .H A. PORTION Or THE SW -1/4, SECTION 5 T27N I14'E WM i GENERAL NOTES 1. ALL WORK AND MATERIALS SHALL BE IN ACCORDANCE WITI-1 CITY OF EDMONDS STANDARDS AND SPECIFICATIONS AND WASHINGTON STATE DEPARTMENT OF TRANSPORTATION 1994 STANDARD � SPECIFICATIONS FOR ROAD, BRIDGE, AND MUNICIPAL CONSTRUCTION. 1 2. ALL WORK WITHIN ITIE SITE AND CITY RIGHT-OF-WAY SHALL BE SUBJECT TO THE INSPECTION OF THE ` CITY ENGINEER OR HIS DESIGNATED REPRESENTATIVE. daQU�pp � o 3. PRIOR TO ANY SITE WORK PERTAINING TO DRAINAGE, THE CONTRACTOR SHALL CONTACT THE CITY NOTES: OF EDMONDS CHIEF INSPECTOR TO SCHEDULE A PRECONSIRUCTION CONFERENCE. DUE TO FIELD FRAME AND GRATE BOLT LOCKING RING & COVER FINISHED GRADE CHANGES REQUIRING REVISIONS, A REVISED CONSTRUCTION PLAN, SIGNED AND STAMPED BY THE (SEE STANDARD PLAN FOR DETAILS)q 1. CATCH BASINS SHALL BE CONSIRUCIED IN ACCORDA14CE WITH ASTMC478 ENGINEER OF RECORD SHALL BE SUBMITTED TO 111E INSPECTOR AND APPROVED BY 111E PLAN (OR NO D I99) E C890 UNLESS OTHERWISE PECIFISHOW1 ON ,,� PLANS OR NOTED IN THE WSDOT/APWA STANDARD SPECIFICATIONS. MAX. AIR VENT- ... CITY ENGINEER PRIOR TO CONSTRUCTING CHANGES, i y' S+ DESIGN AT CROWN 3 2. AS AN ACCEPTABLE ALIERNAIIVE TO REBAR, WELDED WIRE 4. THE TEMPORARY EROSION/SEDIMENTATION CONTROL FACILITY SHALL BE CONSTRUCTED PRIOR TO ANY 4 "30" FABRIC HAVING A MIN. AREA OF 0.12 SQUARE INCHES WSE 2" MIN. DIA. 2017 GRADING OR EXTENSIVE LAND CLEARING IN ACCORDANCE WITH THE APPROVED TEMPORARY EROSION/- - Z� PER FOOT MAY BE USED. WELDED WIRE FABRIC SHALL COMPLY ,' TO ASTM A497 (AASITTO M 221). WIRE FABRIC SHALL NOT BE 80LF - 72"CMP SEDIMENTATION CONTROL PLAN. THESE FACILITIES MUST BEI SATISFACTORILY MAINTAINED UNTIL S" PLACED IN KNOCKOUTS. 12' RISER- - _2' 12 GA GALV STEEL W/ CONSTRUCTION AND LANDSCAPING IS COMPLETED AND THE POTENTIAL FOR ON -SITE EROSION HAS y MAX. 3x1 CORRUGATIONS MAX. PASSED. i RISER SECTION 3. ALL REINFORCED CAST -IN -PLACE CONCRETE SHALL BE DETENTION PIPE LU 0 - �� ,�' CLASS 4000. 5. ALL STORM SEWER PIPE IN ROADS SHALL BE ADS DOUBLE WALL SMOOTH INTERIOR, N-12 T.M. \6" SECTION S=0.00% POLYVINYL CHLORIDE (PVC) PIPE, SDR 35, IS ACCEPTABLE FOR LOT DRAINS. T 4. PRECAST BASES SHALL. S "ALL HAVE WI111 CUTOUTS E _ F6" DEAD STORAGE � 1-/f3 BAR HOOP KNOCKOUTS. KNOCKOUTS SHAIl t1AVE A WALL THICKNESS 6. ALL PIPE SHALL BE PLACED ON STABLE EARTH OR IF IN iTHE OPINION OF THE COUNTY ENGINEER, THE OF 2" MIN. ALL PIPE SIIALL. BE INSTALLED IN FACTORY - - - - y' S, PROVIDED KNOCKOUTS. UNUSED KNOCKOUTS 14EED NOT W rms� EXISTING FOUNDATION IS UNSATISFACTORY, THEN IT SHALL BE EXCAVATED BELOW GRADE AND BACI<FILLED BE GROUTED IF WALL IS LEFT INTACT. �36" MIN. DIA. 36" MIN. DIA. h' WITH A GRAVEL MATERIAL TO SUPPORT THE PIPE. 34 4 20, 5. KNOCKOUT OR CU10UT IIOLF. SIZE IS EQUAL TO PIPE OUTER CONNECTOR CONNECTOR 0 7. THE BACKFILL SHALL BE PLACED EQUALLY ON BOTH SIDES OF THE PIPE OR PIPE -ARCH IN LAYERS WITH Z DIAM. PLUS CATCH BASIN WALL THICKNESS. FLOW PIPE PIPE Z A LOOSE AVERAGE DEPTH OF 6", MAXIMUM DEPTH 8", THOROUGHLY TAMPING EACH LAYER. THESE 5 5" RESTRICTOR SDMH A-7 COMPACTED LAYERS MUST EXTEND FOR ONE DIAMETER ON EACH SIDE OF THE PIPE OR TO THE SIDE 6. KIJOCKOUIS MAY BE ON ALL 4 SIDES W1111 MAX. DIAM. OF 20". �l �'� .''� �``. � � KNOCKOUTS MAY BE EITHER ROUND OR "D" silnrE. 'TYPE 2 CATCH BASIN OF THE TRENCH. MATERIALS TO COMPLETE THE FILL OVER PIPE SHALL BE THE SAME AS DESCRIBED. SDMH A-6 54" DIA. 0 �^ (REFER TO WSDOT STD. SPEC. 7-04.3(3) AND STD. SPEC: 2I 03.3(14)C, METHOD B & C.) RISER SECTION ;cam " , �� 7. TILE TAPER OIJ 111E SIDES OF 111E PRECAST BASE SECTION 12" SECTION AND RISER SECTION SHALL NOT EXCEED 1/2"/FT. TYPE 2 CATCH BASIN 8. ALL CATCH BASINS SHALL BE TYPE I OR TYPE II AS NOTED ION THE PLANS. t : 54" DIA. FI_EVATION VIEW 2-#'3 BAR HOOP 1 8. CATCH BASIN FRAME AND GRATE SNAIL BE 114 ACCORDA14CE i 9. THE CONTRACTOR SHALL BE RESPONSIBLE FOR ADJUSTING. ALL MANHOLE, INLET, AND CATCH BASIN WITH STA14DARD SPECIFICATIONS AND MEET 111E SIRENGIH FRAMES AND GRATES JUST PRIOR TO POURING OF CURBS AND PAVING. 11J REQUIREMENTS OF FEDERAL SPECIFICATION RR-F-621D. 0 I A 11 4" MATING SURFACES SHALL BE FINISHED TO ASSURE 01 ES: o , MIN, Non-RocKING FIT WITH ANY COVER POSiRON. 1. NEOPRENE GASKETS REQUIRED AT ALL CMP AND CPE PIPE JOINTS. 10. ALL CATCH BASINS WITI-1 A DEPTH OVER 5.0 FEET TO THE LOW LINE SHALL BE TYPE II CATCH BASINS. ' Z6 22+ 9. FRAME AI ID GRATE MAY BE INSTALLED WIiN FLANGE DOWN 2. ALL METAL PARTS SHALL BE CORROSION RESISTANT. STEEL PARTS SHALL BE GALVANIZED III I OR CAST INTO RISER. z 11. ALL CATCH BASIN MANHOLES, INLETS AND CATCH BASINS SHALL HAVE LOCKING LIDS. 4 , 4 AND ASPHALT COATED(TRFATMENF 1 OR BETTER). W I �'''� II I 1 `` �IN 10. MAX. DEPTH FROM FINISHED GRADE TO PIPE INVERT SHALL 12. ALL STRUCTURAL FILLS SHALL BE COMPACTED TO A MINIMUM OF 90% OF MAXIMUM DENSITY BY J- i i BE 5'-0". 3. CAPACITY OF OUTLET PIPE MUST BE EQUAL TO OR GREATER THAN ALL INLET PIPES COMBINED. Q STANDARD PROCTOR TEST. (SEE GEOTECHNICAL NOTES ON i THIS SHEET). /' 1� i 1 1 ! 3 BAR EACH CORNER-/ I ' 1 1 11. EDGE OF REDUCING SECTION OR BRICK SHN L n'QT BE MORE � i � i THAN 2" FROM VERTICAL EDGE OF CATCH BASIN WALL i 13. STANDARD LADDER STEPS SHALL BE PROVIDED IN ALL CATCH BASINS/MANHOLES EXCEEDING FOUR (4) I ` I o i = Q FEET IN DEPTH. ( � i I `�' PRECAST BASE SECTION a 15. BACKFILL TRENCH OF NEW UTILITIES SHALL BE COMPACTED TO 95% RELATIVE COMPACTION UNDER I I'' i I (MEASUREMENT AT THE TOP DETAIL. -- L of In 13 ON PIPE STRUCTURE i ROADWAYS AND 90% RELATIVE COMPACTION OFF ROADWAYS, AS SPECIFIED IN SECTION 2.03.3(14)D I I -� I OF THE BASE) ✓�1 AND SECTION 2-03.3(14)B. ( I �'� �- i V NO SCALE 16. STORM WATER CONVEYANCE FACILITIES MUST BE FLUSHED AND CLEANED PRIOR TO CITY OF EDMONDS -��.� I #3 BAR EACH WAY ACCEPTANCE. �3 BAR EACH SIDE : , i r • i 20' ACCESS & , i WILI tY ESM L 17' MIN I �.. 2' MIN i I � GRADEEXISTING DETAIL � CATCH BASIN TYPE I EXTRUDED CURB (TYP) 3 PER DETAIL 1, THIS SIiEET ; NO SCALE - y o / I ^ pp1 N / R DETAIL 6 TELLS SHEET. I Z III I I I 'O cv I ROCKERY PER ET, g - ROCK SIZE PER GEOTECHNICAL AND GEOTECHNICAL ENGINEERS a TIC(- RECOMMONDATIONS RECOMMENDATIONS -_ T CLOSED v-- PERF. PIPE 0 EN � m .• -�111 fI DRAINAGE SYSTEM :'. il_I]-----8~ MIN. THICKNESS 2" COMP. DEPTH CLASS 'B' ASPHALT ! I `� _ _ _ _ �r"-.2" QUARRY SPALLS 2" COMP. DEPTH CR. SURFACING TOP COURSE _ II -II- _ - N- _ • • � ii�n7 4' PERF: PIPE _< o pD 4" COMP. DEPTH CR. SURFACING BASE COURSE o CENCLOSED DRAINAGE SYSTEM -f 111 (BASE APPROVED BY ENGINEER AND GEOTECH) - - _ CONNECT TO STORM li - I I I DRAINAGE LINES tF! m t1' 1 X N • I I I I_ I I I 1=III 1= POWER, TELEPHONE 1 "x: ��A. & GAS SERVICES I t -tr„ , rt •.1to INDIVIDUAL 1 /2 PE - dYp . + . O i WATER SERVICE 6" PVC SAN. SEWER pJ 4'-6" (MIN) I T'•1=+ �y) �, .. i RISER DETAIL " RO K WALL. � r S� ACCEM FAST ENT tiv �� W'�'�,e w o t ,�, NO SCALE WCQ NO SCALE 0 H 02 54" TYPE II C.B. U d' U3 4 10" 24" DIA ACCESS lON1►L --- -- , A `�+ w H 5" _I1/2" ti WITH LADDER 12 TOOK' FOCI, +ItX tiVt'17I TILL�SLCTION 2 1/2"- 1 •- 2 1 /2" ►�XPIPtffs 2! lg i t co j PLAN A � •-•� W 6 FI' i o TENSAR UX15oo _ a ROUND SOLID LOCKING p " ,' COVER MARKED "DRAIN" GEOGRID 6 FT' _�'� COMPACT ` 1 1/2 R. . m ELEV=183,00 AIL), 3 FT r-7rn` . 1 1 /2" R. LIFT ROD HANDLE CLEANQUARpy' ,/ \ 3 FT i LIFT ROD -- - z SPA1,L DRAIN Z FT 1,0 DETAL�' DED ��no � - OVERFLOW ELEV=179.78 1 F'j"1 j-�jC�jEOs � i`�. NO SCALE I El` ..• \ \/ �\ � Z Q j I ORIFICE NO. 2 DIA=21/2" 4 INCH ll1AM. I ELEV=178,28 PEW PVC PIPE f </\ 2:1 P ---__PIPE SUPPORT: BOLI�DTOR IMBEDDED �, / .. ��: ,may_--•-• ... r•/ '•-,.,--_----•�,� 1 I DETENTION 2" IN WALL AT MAX. 3' SPACING. SD PIPEIzz ,,!1 -- - 2LF-36"CMP ` ,C�C:� C > r��!'j"l.t`7 {--� r� t r �C-�? I �i h ✓t=-t..\� o '.,� 12 SD OUTLET ROCI I'IIY COIVSTRUC'�'�ON C�.IT'iCA'�'�ONS r ► �. r � l.) Rock sb»I1 be hard, durable 6-Man (70001b) rock for basa(3-eourscs, rcruainder shall, be 4-Manrock In 1 IE=174.28 2.) Long dimension of rock shall extend into earth and each rock should bear on two or mare rocks ! ._ ,-• E- b. 2:1 ( IE=173.78 3.) Drainage material shall consist of clean quarry, spells with 3 inch maximum sizer:'. 1 /\�T ✓ W �-- - \�CLEANOUT GAIE/SHEAR GATE 4.) Drain pipe shall be 4 inch -diameter perfmted PVC ripe I 'd in drain, rock with �adlcrttto-tic t3ghtliuc ... /� � ;�i, - LADDER STEPS . SEE DETAIL 5.) Mockery shall be embedded at Jeast 18 i r hr ge t� 'C� f C-v0 �z�Grtz��z V) Y napes and shall br_ar on native dense soils 1 STANDARD GALV. STEEL o 6.) Rockm7 face shall not exoeed 1H:6V (Horizont EVertieal) incUuution z� U -z� CV l 1 xPIPE PIA.TYPE II 54" C.B. RESIRICIOR PLATE 7•) Oeo-grids shall be 6 foot 1mg111 Tensar UX1500 ore uivalent,'laid flat on p 1a q prepared level surface, overla l i< 81 RE 1 1/2" DIA. 8.) Fill shall be Send, Gravel or Pit -rue free of deleterious or organic mutaial, placed in 8 inhh Lila & compacted \ �" z M: ELEV=172.28 9. All fill shall be c a o 12" ORIFICE NO. 1 ) °nTI' ctcd to meet or exceed 90 /e of modified proctor max dry density, (Asrm-D-1557) � U 1: t ROQUI RY CONSTRUCT.[ON PROCEDURE o SD PIPE ELEVATION O 0 0 U O I i ) Dill bench shall be excavated, and existing topsoil, hose soils and vegetation shall be ientoved fium the slope 2,) Fill shall be placed $ coiazpacted & gco-gilds placed as shown in disgtaTrot _up to proposed road slTbgrade a Z o 0 12" THICKNESS, f O 8" QUARRY SPALLS 1 (">,'1' j� o, /\,� [�; �n>9� 3.) Placed and compacted fill wedge area shall be cut at proposed rockery locafian °' o J DUAL A A � ol'W O 4'.) Rockery shall be couslztr>:ted agai;;,st cut fill wedge at rite saute time dtaluag • ' FLOW OO OL S'T�iucivf�E �- - , .- , ... a system is installed «�* I SCALE: 1"=3.-O" �- - _ Q > W ■/q'� DUAL - Pi OT O /`� j.•.l c� 1:.r I- '-I I -.; �:� ::; ir. ir.. 1 f7 I <.a T_I >^Jp -�z� �z�-� �,�-...t t�l v f`�t c�rz• t� - F'flOYED FO�i CCJNSTf iUCT10N o H fib L.---1 .'r .--� ..� r j z H NO SCALE ( _ _ I E I n 1- I . � . F . !- . � L�r.- m P.-A r_.1 r._p fill:) , . I... �� -•�_ /-1'�' .., - I � .. t ,__ T � D C.7�.'� W r� .'L. I ,� r• ��) .... '.!! , �r•...r C,•, I �_,1�. '' ' I r' '} = .,� , !. ) CI IY OF E0610HUS ENGINEER DATE o l I ( v A 04� rZi 1 300 290 270 260 Z 0 m 9m A PORTION OF THE SW 1/4, SECTION 5, "1-27NI MEY W.M. 310 I I \ \ \ I 300 f \ \ EXISTING GROUND \ \ FINISHED GR E \ 260 IS �\ 2901_ \\� ST STA 3+49 \ R1=260.00 \ \ i IE = 250.00 - 6" 240_ \\\ CB A-3 TYPE 2 4-80 GR I E= 259.50 ��,c• IE= 245.00 - 1 _`11 280 IE=252.50 - 1 _"S CB A-1 TYPE 1 I \\\ GR I E= 288.00 IE 285�.00 - 12"N `r\\ \\\ l I o \ t \ 1-1. 00 6' SS CLEANO T S STA 4-1-49 RI=279.50 --_.._-__.___-I_._ IE 271.5U --- L C13 A-2 TYPE 1 I GG ATE= 271.0 IE 268.00 - 12"N,S 2 -00 230 A _._.__. GUARDRAIL PER WSDOT IDS OCK WALL 6 \ \ PROVIDE 10LF-18"S TEEL SLEE E FOR DRAIN PIPE UNDER ROCKERY EXI 31114G GROU14D LC � \ • \ 122CF 12„ o \ CB-A-4 -TYPE 1- - - W/ SOUL LOCKING COVER \\ GRATE=2 4.00 \ IE=231.0 - 12"N,S 100CF \\ 6"SS CLEA 40UT SS STA 2-1 49 \ RIM=230.0 ) IE=224.00 - 6" \ W/ SOLID LOCKING CO ER r - - GRAIE=22 .00 \\ IE=224.00 - 12"NE,SE �\ MV \ b0 SSMI-I 2 RIVATE \ SS STA 1-1 49 \ RIM=226.0 " IE=218.00 - 6" �o \ l� 200 \ \ E) 190 \\ EU 4� \ \ u� w 17, . MEADO DALE R AD 1 GRADE 11 270 l.Fj{ M1 4f s d t � •0 Gk III d < t tyt� $, g i ltt6 K�.Y tK+�� -w'Q�. •gyp. ltk�! yt� M r :h250 b:�f F4`iJ, y % (iY1 i� 22C CD 210 rI �V O N Cs� N T �W� y C) 0) �o a`t{ 0' of U1 w .-•� V) N o WV) H N J Q �W X \\ i� t 180 U_ __._._____.. -_ _ _-__.____ 180 t Q g -10 F-12"SD =1.00% 180 C w 50.F 6"PVC =1.00% 170 _ _ _ _ _ -._ _-_ _ _ _ _ 170 6 SS CLEAN OUT SSMI-I 1 _ INSTAL OVER EX •MIN SS STA 21- 49 SS ST 0+00 RIM=184-.0033 o n Q RIM=1 .50E o IE=173.87 6° IE=17 .20 - EX I. "E,W cO .. -.I E=17 r37 ----N E W 6 "S_ _._ _ _. _ _ _ _ _ __ .. _ _ _._._ _ _ __ _ _ _ . � � 0, a i CB A-6 TYPE 2 54 °' W/ FLOW CONIROL-IRUCTURE $ �' � o ROAD, STORM A D SA ,CRY � WEB i��QFIL RIM=183. )0 CB B_2 TYPE 2 480 � a o `� W I _ IE=173.7 - 36"W W/ SOLID LOCI ING COVER At'P110 D -Ofl C N�TflUCTI N z �, z 5C LE: H1 "=20r _ 1_ =5' RIM 182.00 IE=174.18 - 12 S E W T g 0 w CI OF DMONDS ENGINEER DATE i % Q /6/18 7��/ e � V-I to M t- o V OCT.z6.2000 12:48PM M.H.S. 1562148 PI W. Edmonds, WA 98026 NO.184 P.Zi2 October 24, 2000� TO: Meg Gruwell, City of Edmonds FROM: John E. Thoresen RE: Information on LOT 2 quoia Ridge As per your Plan Review Comments of October 16, 2000, I offer the following. 1, Regarding your #2 of the comments, on the portion of the site that is identified as Native Plans per Ceotech, both the Geotech and the Biologist have determined the following: Where any dirt has or could be disturbed, we will seed the ground a2th a mixture of native grasses and also plant salal every three feet on center. The salal plants Nvill come in one -gallon pots. The native grasses will hold the soil until the yy ,. . salal groves togerther which should be 2 to 3 years. ' 20' bNIIDE AC(;E55 EASEMENT s Ca �, � Y � A v K 0 n /`t7 N 8q°S8'4" W I � III. 7��,s ,see c_,� -�- I�