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6925 163RD PL SW.PDF883 6925 163RD PL SW CITY OF EDMONDS STREET FILE ASSET INFORMATION SHEET 2' NEW ADDITION RETIREMENT ASSET NO. �ff2 V ADDITION TO ASSET NO. DESCRIPTION SERIAL NO. LOCATION (09 a 5 1 0 1 5 -uj DEPT. NO. * * PURCHASE ORDER NO. PURCHASE ORDER DATE COST PROJECT NUMBER �&) 9 -;:IS 0 9 7 PROJECT COMPLETION DATE 9 -30 -67 COST /;?- �- Y�� B.A.R.S. ACCOUNT NO. (000 -()1 3YS-- 0()(03 ESTIMATED LIFE INITIATED BY DATE APPROVED BY "SUBMIT ASSET INFORMATION SHEET WITH FINAL PAYMENT REQUEST *SUBMIT ASSET INFORMATION SHEET UPON CLOSE OF PROJECT ACCOUNTING ONLY iDEPRECIATE MONTHLY DEPRECIATION AMOUNT ANNUAL DEPRECIATION AMOUNT G.L. ENTRY REFERENCE DATE INITIAL wp) DEPARTMENT FILE �IVERIFIED BY PROCESSED BATCH NO. -�d_ co C) r0:2 CUT of EDMONDS DE SEWER PEflM.1,,-T_';J STREET FILEs. .For Inspection Call 771-3202 PERMIT NO. 08034 JAJ Address of Construction: Property Legal Description (Include all easements): OT L !A Q Lk-i H-1 e�) D Owner and/or Builder: k (�7 Contractor & License No: L/ 6:_ DO 92 Single Family Residence Multi -Family (No. of Units Co mmercial (No. of fixture'Units, Invasion into City Right -of -Way: No Yes (If Yes, Right -of -Way Construction Permit required. Call One�Call-Center (1-800-424-5555) before any ,excavation.) Cross other Private Property: No Yes (If.Yes, easement required, attach legal description and county easement -number.) PLEASE READ THE ITEMS LISTED ON THE BACK IRECLI V L L, I t-1 y tn-at'l have read and shall comply AUG Date r wi h the items listed on the back. PUBLIC WORKS Permit Fee:, _2>0 Issued,By: (*17 Trunk Charge: rDate I ssued: Assessment Fee: Receipt No.: Partial Inspection: Comments Date 1nitial Final Inspection Approved: Ln Date Initial Rejected: Reason Date Initial PERMIT MUST BE POSTED ON JOB SITE Wh.ite Copy File Green Copy -'Inspector Buff Copy Applicant The City of Edmonds Side Sewer Drawing EASEMENT NO - -------------------------------------------- NEW CONSTRUCTION REPAIRS F� LID NO . ...... ----------- ASMT. NO. � ----------------- OWNER ------------------------------------------------------------------------------------------------ CONTRACTOR ------ ------------------------------------ PERMIT NO . ................... JOB ADDRESS ----------------------------------- U� --- LEGAL DESCRIPTION: LOT NO . ...... ---------------------- BLOCK NO - ------------------------------------ ----------------------- LY I ----------------------------------------- --------------- ---------------------------------------------- CAD 01%kv. 6 r- 2 to, po % L) t3 I -- tqo� �lle-Amtu,�T)Qaf, PWW-0001 -11/75 (REV. 11/78) ele'D - I EE�HE 17 [3] Lj � 6 CFL R Pla Approved: DATE ... ------------- By -------------------------------- ---------------- A ...... NOTICE: No warranty of accuracy. The information shown on the attached map(s) was compiled for use by the City of Edmonds, its Employees and Consultants. The City of Edmonds does not warrant the accuracy of anything set forth on these map(s). Any person or entity requesting a copy should conduct an independent inquiry regarding the information shown on the map(s), including, but not limited to, the location of any sewer stub shown. Such sewer stubs may or may not exist and may or may not exist at the location shown. Neither the City of Edmonds nor its employees or officers shall be liable for the information given on map(s), nor for any one representation provided based upon said map(s). if DAVID L. NELSON AND ASSOCIATES, INC. Consuiting Enalneering Geology 13424 Chaidtake Road Monroe, Washington 98272 2061794-4332 a I December 6, 1983 Project No. 5983 Rk�C!9�MF_D 1; MAR 2 7 FF'l SIMCO PrA,111 COUNTER c/o Subdivision Management, Inc. 16031 — 111.9th P" ace N'17' L Bothell, Washington 98011 S Attention: De -En Lang o L, 141 r, 0 44, Reference: Preliminary Soils Investigation Meadowdale Heights Edmonds, Washington Gentlemen; This is to serve as a report of a preliminary soils investigation performed at the above referenced project site, per your request-. Introduction The' purpose of this investigation is to determine suitability of the site for development as proposed. We understand that construction is to consist of single family residences and U14 I il; ES associated roadways and v-L-L U� The scope of service s --"included performance of fifteen backhoe test pits, located generally within the proposed development areas and within those areas believed appropriate to obtain information for presentation of conclusions and recommendations contained herein. Approximate locations of the test pits and general features of the site are shown on the enclosed location map. Elevations All elevations mentioned in this report refer to existing grade and to a land use study plan topogr_nphic mapp supplied to us by you. DAVID L. NELSON AND ASSOCIATES, INL. Consulting Engineering Geology December 6, 1983 Project No- 5983 Page two Location & Site Description The investigated site consists of approximately 12 acres lying between 68thAvenud West and North Meadowdale Road in Edmonds, Washington. Presently, the site area is primarily undeveloped, except the upper elevation areas within the eastern portion of the site# where some site grading and utility installation had been per- formed in the past. Topographically, the site generally slopes toward the northwest from an upper elevation area within the eastern area to the lower elevation areas toward the west. The primark features of the site observed during field explora- tion consist of two draw areas approximately shown on the locatior map,the moderate to steep slopes and a top -of -slope approximately shown on the location map. The area is heavily vegetated, with many evergreen and deciduous trees, underbrush and grasses. Soils Conditions The subsurface soils stratigraphy is best illustrated on the enclosed test pit logs. In general, the site area appears to be underlain by grey -brown to grey, medium dense, poorly sorted,slightly silty to ' clean, - sand with much gravel. These soils are found primarily within the lower elevation areas along the west side of the site, and on a portion of the lower slope areas. These materials appear to consist of recessional glacial outwash deposits. Within the moderate to steep slope areas and underlying the recessional outwash deposits, is a strata of grey -brown to grey, dense, silty to slightly silty, poorly sorted sand with much gravel. These materials appear to consist of advance glacial outwash deposits. Within the upper elevation (eastern) portion of the site, the soils consist of grey, dense, poorly sorted silty sand with gravel, considered to be glacial till. The glacial till appears to overly the advance glacial outwash materials, and is found somewhat below the approximated top -of -slope line shown on the location map. DAVID L. NELSON AND ASSOCIATES, IN%.. Consulting Engineering Geology December 6, 1983 Project No- 5983 Page three The surficial soils directly overlying the parent material discussed above generally was found to be uniform in nature, except within the draw areas.. Generally, the surficial soils consist of l' of organic topsoil, underlain by 1-5'- 2' of brown loose silty sand with roots and some gravel. A weathered soil zone of the parent material is found between the root ladden zone and the parent material, generally consisting of brown to oxidized brown, poorly sorted silty sand with gravel in a medium dense condition. Within the draw areas, the sur- ficial soils are somewhat thicker and the weathered zone some- what deeper before the parent material is reached. Hydrologic Conditions The ground water table was not encountered in any of the test .pits performed within the site area. We did encounter some perched water conditions within the central draw area, located within the weathered zone above the denser parent material. This perched water appears to be related to drainage within the draw, derived from an outfall which empties into the draw from under 68th Avenue West, and accumulated surface waters within the drainage area of the draw. Seepage was not observed within the test pits located outside the draws, although we would expect some seepage after prolonged precipitation periods, due to the contrasting permeabilities of these soil units. No evidence of outcropping ground water was observed within the site area, although some surface water was observed within the easterly portion of the central draw and within the northern draw area. __'Slope Litv Y Observation of the slope conditions throughout the site area did not indicate any noticable unstable slopes, slides or earth flows/slumps. Some past instability is apparent within the area of TP-15, along th e north facing slope. This may be due to the existance of the draw, and the normal backwasting DAVID L. NELSON AND ASSOCIATES, IN%_ Consulting Engineering Geology December 6, 1983 Project No- 5983 Page four processes associated with this area. Vegetation and general ground conditions did not indicate chronic earth movement or instability within the investigated areas. We have reviewed the report prepared by Roger Lowe Assiciates, Inc., dated October 16, 1979, titled 'Final Report, Landslide Hazards Investigation, Meadowdale Area, Edmon ds, Washington', prepared for the City of Edmonds Public Works Department. This report discusses the existance, properties and occurrence of a slide area which exists several hundred feet to the north- west of our study area. We believe, based on that report in- formation and our findings, that our study site is not an active portion or major contributor to the -noted slide area. The Lowe report discusses several recommendations to aid in reducing slide activity within the area. We understand that provisions will be made in our study area for control of all storm water runoff, and construction of sanitary sewers for the proposed residences. In so doing, a reduction or maintainence of the surface and potential ground waters effecting the slide area from this development is expected. Conclusions Based upon the investigation performed, proposed site develop- ment and review of existing information within the site area, we believe the proposed residential development can be performed as anticipated, provided recommendations as presented herein are utilized for construction and development. Recommendations Residential dwellings are proposed within three main areas of the site; within the southerly upper elevation area, within the northerly upper elevation area and within the area of the cen tral draw. Foundation placement and slope stabilization tech- niques should be anticipated within these areas to maximize .existing stabiiL�Y_ DAVID L. NELSON AND ASSOCIATES, [Nt-. Consulting Engineering Geology December 6, 1983 Project No. 5983 Page five Within the upper elevation areas the residences are,Planned to be located near the top -of -slope. We suggest that foundations for these residences be placed into the ense glacial till soils, ---------------------------------- ----------------------------- 4 --------- b__e__ 1ow 6�=a glacial till soils were found found 31' to to be quite dense and stable and should make excellant bearing soils. Development near the top -of -slope areas should be per- formed such that artificial fill is not placed along the top - of -slope nor over the slope area. A ny existing fill material should be removed from ne e top -of -slope and_re��_eg_e_Fated- Continuous or spread footings, using a maximum allowable soils bearing pressure of 2000 pounds per square foot (psf) should be anticipated within this area. Residences planned for construction within the central draw area should anticipate foundation placement into the medium dense weathered strata or into the dense underlying parent soils directly underlying. Excavation into the slope areas is under- stood to be expected within this area. We g3�ggest that footings be placed on natural soils of uniform r_Qn_-_tZL-_�iC_Yf rather than varying soils materials. This may require stepped type footings within some areas, to achieve desired foundation soils. Within excavations which occur into the slope areas, we suggest that retaining of the slope be performed. This could be accomplished through construction of retaining walls along the upslope side. __�ei_ain_i'n_gwa1l_s -are exp--ected to be less than 10' in height in this area. We suggest that foundations and retaining walls utilize maximum allowable soil pressures of 2000 psf where founded into the medium dense natural soils. Equivalent fluid pressures of 70 pounds per cubic foot (pcf) should be anticipated against the retaining walls. An adequate drainage system should be performed behind retaining walls constructed within the area. We suggest e ns consist of a perforated pipe placed a -Long. the base base of the wall, connected to a gravel backfill drain behind the wall which is a minimum of 18" thick. The drain pipe should be connected to the main drainage system. We have DAVID L. NELSON AND ASSOCIATES, h Consulting Engineering Geology December 6# 1983 Project No- 5983 Page six enclosed a subdraih and backfill scheme which generally shows the recommended drainage for retaining walls within this area. Dewatering of some of the excavations within the draw area may be necessary. This could be accomplished through construc- tion of interceptor drains or french drains around the structure area where required. Additional Notes Adequate drainage should be provided around the structures consTr—ucfe—CwTit_hin the investigated area. We suggest the use of foundati and roof drain_systems, independantly con—s-trMated and directed into the main storm drain system. Storm drainage is recommended to be controlled and detainage systems constructed such that accumulated wat ers are restricted from seepage into the subgrade soils. We would suggest either a burried pipe or vault detention system rather than an open detention pond system, which could allow seepage into the soils. Road I ways should anticipate conventional pavement sections, although the use of Asphalt Treated Base would be adviseable during the wetter periods of the year. Roadway development within the central draw area should anticipate the existance of either a channeled or burried pipe system nearby within which the water from the outfall under 68th Avenue West can be directed. Additional subbase gravels may be required to more effectively stabilize the roadway section than inothe upper elevation roadway areas. The rockery which occurs along the west side of 68th Avenue West, at the head of the central draw was observed to be only margin- ally stable. Settletent within the roadway was observed, and is expected to continue. We suggest this area be considered for stabilization, through either the construction of an adequa retaining wall or structurally filled. Additional investigation of this area should be performed, to determine an effective stabilization method. Construction activity within the site DAVID L. NELSON AND ASSOCIATES, h_ fo Consulting Engineering Geology December 6, 1983 Project No- 5983 Page seven may effect the stabilty of the rockery, since it is. unknown whether stabilization methods were utilized during construction of the roadway within the area. Winter earthwork within the central draw area for placement of residences may require shorirfg, backsloping or other methods within the excavations to maintain slope stability. The occurrence of surface and/or ground water within the excavations may create conditions which require stabilization methods. Although the soils within the area are considered relatively stable, open excavations can be readily effected by freeze -thaw, surface erosion and factors relating to the inclement weather conditions. L, Inspection of the earthwork phase of development within the site area should be performed, including excavations, foundation placement, retaining wall placement and drainage. Structural fill used within the site should consist of granular soils generally approved for use, uniformly placed and compacted, and inspected as required. Although we do expect site soil types, conditions and distribu- tions to reflect our findings, some variations could occur. Should conditions other than those discussed herein be encoun- tered, the soils consultant should be notified for review and comment. Additional or alternative recommendations may be requi.— Thank you for the opportunity to be of service. If you have any questions, feel free to call on us at any time. Sincerely, Daviae d. n ssociates, Inc. ;av�iid L. Nelson, PG J. Keith Cross, PE Consulting Engineering Geologist Geotechnical Consultant DLN: kmn SLOPE OU DE GRADE AWAY FROM STRu%;TURE FOR DRAINAG ............. PAVEMENY OR 118 INCHES MIN. TAMPED TOPSOIL OR IMPERVIOUS SOIL P.M1 Sid In. GENERAL FILL WEEP HOLES 7. SUBDRAIN PIPE F not to scale MATERIALS SUBDRAIN PIPE f5ia—. Perforated Or Slotted Concrete, Metal, Asbestos -Cement Or Plastic Pipe. Tight Jointed, Sloped To Drain (4" / 1001 min. slope), With Clean -Outs. Slotted Pipe-- 1/8" Max. Width Slots Perforated Pipe-- 3/16" to 3/8" Holes Slots Or Perforations Preferentially In Lower Half Of Pipe With Lower Quarter Segment Solid For Water Flow. DRAINAGE SAND & GRAVEL 'To—�i-e—et—W—as—hin—gt—on—St—at—e —Sp—ecifications Or The Following Gradation. Sieve Size Passing By Weight I- I / 2" 100 3/4" 70-90 1/ 4" 30-60 No. 8 20-50 No. 30 8-30 No. 50 3-12 No. 200 0-1.2 (by wet sieving) (non -plastic) E�� EXTERIOR RETAINING WALL DAMP PROOFING VAPOR BARRIER -, CONCRETE SAND " " r4 �� FLOOR SLAB DRAINAGE SAND & GRAVEL NOTES 1. Drainage Sand & Gravel Beneath Floor Slab Should Be Connected Hydraulically To Subdrain Pipe. Use Of 2" Dia. Weep Holes Is One Applicable Method. 2. Subdrain Pipe Should Be Bedded With A Minimum Of 6" Of D.rainage Sand & Gravel Surrounding The P'-P 3. E�ckfill Within 18" Of Wall Should Be Compacted With fland-Operated Equipment. Heavy Equipment Shou.' Not Be Used For Backfill, As Suc.-. Operation Could Increas.e Lateral Earth Pressures And Possibly Damage The Wall. 4. All Backfill Should Be Placed In Layers Not Exceeding 6" Loose Thickness And Densely Cumpactc:d. Beneath Paved Or Sidewalk Areas, Compact To At Least 9576 Modified Proctor Maximum Density (AST -NI: D1557, Method C). Otherwise Compact To 90",In Minimum. SUBDRAIN � BACKFILL SCHEME BASEMENT WALLS WITH INTERIOR SLAB ON GRADE L, ail a 1L E 13y, ra DAVID L. NELSON AND*ASSOCIATES. INC. Consuiting.EjWr,gWMS Geology 4 13424 Chain Lake Road - Memo% WA U277 . 2MI71%"332 WADOWDALE get-I+T.5 E b VY\ Z) M U s uj A (314 ) N 6 -rb iij SCALE P R 01 NO. —15f� D ATE S HE E T I TEST PIT LOGS TP-1 0-2.5 Brown organic topsoil and fill material 2.5-3-0 Brown oxidized poorly sorted sUty sand with some gravel (weathered till) 3-0-6.0 Grey, dense, poorly sorted silty sand with gravel (glacial till) T-P-2 0-0-5 Black organic topsoil 0-5-3-0 Brown intermixed silty sand and gravel and roots 3.0-6.0 Grey, dense poorly sorted silty sand with gravel (Till) TP-3 0-1.0 * 'Black organic topsoil 1.0-3-0 Brown silty sand with gravel aftd roots 3.0-4.0 Grey -brown oxidized poorly sorted silty sand with some gravel 4.0-7.0 Grey, dense, poorly sorted silty sand with gravel (Till) TP-4 0-1.0 Black organic topsoil 1.0-2.5 Brown. silty sand with roots 2.5-5.0 Grey -brown poorly sorted silty sand with much gravel 5.0-10.0 Grey to dark grey, poorly sorted 'clean' sand with much gravel; pea gravel, many sand & gravel lenses (Recessional Outwash) TP-5 0-1.0 Black organic topsoil 1.0-2.5 Brown silty sand with roots, some gravel 2-5-8.0 Grey, medium dense, poorl sorted sand with much gravel; moist Ucessional) TP-6 0-1.0 Organic topsoil and fill 1.0-2-5 Red -brown silty sand with gravel and roots 2-5-5.0 Red -brown poorly sorted silty sand with gravel 5.0-8.0 Grey -brown, dense, silty poorly sorted sand with much gravel (Advance Outwash) TP-7 0-1.0 Black organic topsoil 1.0-2.5 Dark brown silty sand with gravel and roots 2-5-4.0 Brown silty sand with gravel and some roots 4.0-7.0 Grey -brown, dense, silty to slightly silty, poorly sorted sand with much gravel (Advance) TP-8 0-1.0. Black organic topsoil 1.0-2.5 Brown silty sand with roots 2-5-3.5 Grey -brown, loose silty sand with gravel Seepage 3-5-7.0 Grey, dense, silty to slightly silty poorly sorted sand with much gravel (Advance) DAVID L. NELSON AND ASSOCIATES, INC. Consult ing.EffooWing Geology 13424 Chain Lake R*A WA %2n - M79"332 rArEADOWDAL& 461"T5 Edmonds, Washington 5983 SCALE- PROj. NO. - DATE 12/2//83 SHEET 1 o f 2, " , " . W TEST PIT LOGS TP-9 0-1.0 Black organic topsoil 1-0-3.0 Brown silty sand with roots 3-o-4.o Oxidized brown poorly sorted silty sand with some gravel 4.0-7.0 Grey -brown, medium dense, poorly sorted silty sand with gravel 7.0-10.0 Grey, dense, poorly sorted silty to slightly silty.sand with much gravel(Advance) TP-10 0-1.0 Black organic topsoil 1.0-2-5 Brown silty sand with -roots 2.5-4.5 Grey -brown, loose -medium dense, po.orly QYW��e:t�:) sorted silty sand with gravel ,.y 4-5-7.0 Grey, dense, silty to slightly sill, poorly sorted sand with gravel (Advance) TP-11 0-1.0 Black organic topsoil 1.0-2-5 Brown silty sand with roots 2-5-5-0 Grey -brown, medium dense, poorly sorted silty sand with gravel 5.0-8.0 Grey, dense, poorly sorted sand -with much gravel (Advance) TP-12 0-1.0 Black organic topsoil 1.0-2-5 Light brown silty sand with roots 2-5-5.0 Grey -brown, poorly sorted sand, loose to medium dense, some gr7avel nrtp d s a 5.0-10.0 Grey, medium dense, poorly sorted sand with gravel (Recessional Outwash)__—,-Z gravel fill n ermixed si ty sand wit TP-13 0--2* 2-0-3.5 Grey -brown, medium dense, poorly.sorted silty sand with gravel 3-5-6.0 Grey, dense, poorly sorted silty sand with gravel (Till) TP-14 0-1.0 Black organic topsoil 1.0-2.5 Brown silty sand with roots 2-5-3.5 Grey -brown, medium dense, poorly sorted silty sand with gravel 3.5-6.0 Grey, dense poorly sorted silty sand with gravel (Till) * TP-15 0-2.0 2.0-4.0 4.o-6.o Intermixed silty sand with gravel Brown silty sand with roots Grey -brown, medium dense, poorly silty sand with gravel Grey -brown to gey dense poo�ly si ty sand w h g�ay.el- tTill f ill sorted sorted DAVID L. NELSON AND . ASSOCIATES, INC. Consulfinr�MaWjig Geology 13424 Chain Lake Road - Nwratj WA 982n - 2M,-119."332 MEADoWDALE AF_1&*T5 Edmonds, Washington SCALE — PROJ. NO. _�_983 DATE 12/2/8� SHEET 2 of 2 RECEIVED. Earth Consultants Inc. 1AARZ, 7 1989, Gcol, du Ilk"11 1 --1 igil w(,Is. Grol"91s(s &Lt 1� irt,111 Iw] 1(al St it -I 11ists Geatilinensions, he. IMarch 24, 1989 MAR 27 Kt"! E-4346 Mr. Jim !\.IcGovern 2532 East Mcaraw Street C Seattle, Washington 98112 C Subject: Rockery Construction The Pointe, Lot 20 Edmonds, Washington PERM, IT COUNTER C "TEET FILE ) rl Recommendations R efere n c e: David L. Nelson and Associates, Inc. Preliminary Soils Investigation Dated December 6, 1983 Meadowdale Heights Edmonds, Washington Gentlemen: As requested. we visited the subject site on March 13, 1989 to visually examine the existing conditions at the subject property.. We also reviewed the informaiion contained in the referenced report. The purpose of our visit And review was to determine the nature and adequacy of the site soils and to provide a professional opinion regarding the suitability for rockery construction at the site. This letter addresses rockery construction guidelines for the propo�ed rockeries on the east slope of Lot 20. From our discussions, we understand you intend to construct a series of short (four to five feet high) rockeries to protect a series of terraces dug into the site's east slope. An approximately 2:1 (Horizontal: Vertical) slope is to exiend between each rockery. The finished slope wilt-�e approximately 1H:1V in the rockery terraced area. 'rile majority of the soil slope comprises a medium dense, poorly sorted sand with gravel. I - This is underlain by a dense, silty poorly sorted sand with gravel (see the referenced re I p o rt, Test Pit TP-12). These soils generally have a low to moderate bearing capacity of fifteen hundred (1500) to two thousand (2000) pounds per square foot (psf). Based on our site examination, the information contained in the referenced report, and our experience and engineering judgement, we do not believe your proposed rockery construction 0 plan is appropriate. In our opinion, these short rockeries will be inadequate to protect the terraced slope or to provide any lateral restraint to the relatively loose slope soils. Instead, we recommend constructing two higher, but substantially more robust, rockeries set further C apart.. A 2H:1V slope between the two rockeries is still appropriate. 1805 - 136th Place N.E., Suite 101, Bellevue, Washington 98005 222 E. 26th Street, Suite 101, Tacoma, Washington 98411-9998 Bellevue (206) 643-3780 Seattle (206) 464-1584 FAX (206) 746-0860 Tacoma (206) 272-6608 Mr. Jim McGovern E-4346 March 24, 1989 Page 2 We recommend that two six-foot to eight -foot high rockeries be constructed to terrace the slope. The two basal (bottom) courses should be of six -man to five -man sized rock. The bottom course should be placed in a "keyway" which is at least twelve (12) inches deep The remainder of the rockery can comprise four -man sized rock. As each rockery reduces in height along the slope, the four -man sized rock may be tapered down to the basal courses. By this means, more mass is placed at the base of the slope and thus will provide some degree of lateral support. Each rockery should be constructed in close conformance with the procedures outlined in the Associated Rockery Contractors (ARC) Standard Rockery Construction Guidelines. A copy is attached to this letter for your information and use. The upper rockery should be set back a distance equal to or g ' reater than the height of the lower rockery. This will help avoid the possibility the upper rockery could impost an additional lateral load on the lower rockery. You should understand that rockeries are not designed as structural retaining walls. Their construction is to a large extent a craft not entirely controllable b .y engineering methods. Because of this, it is imperative that rockeries be constructed in a proper manner by experienced contractors with a proven capability in, rockery construction. Please note that a rockery is not intended to function as an engineered structure to resist lateral earth pressure, as a retaining wall would be. The primary function of a rockery is to cover and protect 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 used, the greater the mass and the more lateral load resistance available. 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. Providing the procedures contained in this letter, and the attached ARC Standard Guidelines are implement, the requirements for maintenance can be reduced. However, provisions for future maintenance must be made. If any movements occur, they should be promptly corrected. The permanently exposed slope above the rockery should be seeded with an appropriate species of deep-rooted, rapid growth vegetation to reduce erosion potential and improve the stability of the surficial layer of soil. Earth Consultants, Inc. Mr. Jim McGovern March 24, 1989 LIMITATIONS E-4346 Page 3 Our recommendations and conclusions are based on the site materials observed, our review of the information contained in the referenced report, the design information you provided us and our experiencl- and engineering judgement. No subsurface exploration or laboratory testing was performed by us in this study. The conclusions and recommendation are professional opinions derived in a manner consistent with that level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. No warranty is expressed or implied. We recommend that ECI be retained to perform a general review of the final design and specifications. This will allow us to verify that the rockery recommendations have been properly interpreted and implemented in the design plans and in the construction specifications. We also recommend that ECI be retained to provide geotechnical services during construction. This provides a measure of continuity, allows us to observe compliance with the design concepts, specifications or recommendations. It also allows us to make design changes before or during construction in the event subsurface conditions differ from those anticipated. In addition, we can evaluate the conditions exposed and check'that rockery materials and procedures are in general accordance with the ARC guidelines. We believe these services are critical to the satisfactory completion of this project. Because of the nature of the site soils and the difficulties involved in construction of rockeries of this type, we do not accept any responsibility for the site preparation or rockery construction unless we are retained and perform these services. Earth Consultants, Inc. Mr. Jim McGovern March 24, 1989 E-4346 Page 4 If you have any questions about the content of this letter, or if we may be of further assistance, please call. Very truly yours, EARTH CONSULTANTS, INC. V N tv, Scott D. Dink-elman WA Staff Geologist Glen Mann, P.. E. Vice -President Enclosure: ARC Standard Rockery Construction Guidelines SDD/RJB/GM/kml Earth Consultants, Inc. AR ofmoci,ated 'Xadvery emytr=toui P.O. Box 1794 Woodinville, Washington 98072 (206) 481-3456 or (206) 481-7222 ASSOCIATION OF ROCKERY CONTRACTORS STANDARD ROCKERY CONSTRUCTION GUIDELINES 1.01 Introduction: 1.01.1 Historical Back-2round: These standard rockery construction guidelines have been developed in an effort to provide a more stringent degree of control on rockery materials and construction methodology in the Pacific Northwest. Thq 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 standards presently in use by local municipalities. 2.01 Materials: 2.01.1 Rock Oualitv: All rock shall be sound, unweathered, weathering resistant, angular Iledge 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. All rock delivered to and incorporated in the project shall meet the following minimum specifications: a. Absorption (Coips of Engineers CRD-C-107) b. Accelerated Expansion (15 days) (CRD-C-148) Not 17201-e than 3.0% Not more than 15% breakdown The test sample will be prepared and tested in accordance with Coips of Engineers Testing procedure CRD-C-148, "Afethod of Testing Stone for Expansive Breakdown on Soaking in Ethj,lene Gl),col." Test requirements of not 171ore than 15 percent breakdown will be computed by dividing the number of individual pieces of initial saMple suffeling breakdown (that is, separating into two or 7101-e pieces) ky the total number of initial pieces in the sample. c. Soundness (MgSO4 at 5 cycles) (CRD-C-137) d. Unconfined Compressive Strength ASTM D 2766-66 (roapproved 1979) Not greater than 5% loss Intact strength of 74,500 or greater 2.01.2 Freauencv ofTestin : 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 performed 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. 2.013 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. Typically, rocks used for rockery construction shall be sized approximately as follows: Rock Size Rock WeiAt 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 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. 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 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 rocker), contractor, the client or the applicable municipality. 3.01 RockeKy Construction: 3.01.1 General: Rockery construction is a craft and depends largely on the skill and experience of the builder. A rocke'ry 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 reten- tion, it is not a designed or engineered system in the sense a reinforced concrete retaining wall would be considered designed or engineered. The degree of retention 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 wall. To accomplish this, all rockeries in excess of four feet in height should be built on a "mass" basis. All rockeries constructed in front of cuts and fills in excess of eight feet in height should be constructed in accordance with this standard and the geotechnical engineers supplemental recommendations which should be provided before bidding or the start of construction. The same geotechnical engineer should be retained to monitor rockery construction and to verify, in writing, that the rockery was constructed in general accordance with this ARC standard and with his supplemental recommendations, in a professional manner and of competent and suitable materials. 3.01.2 Geotechnical Enl,,ineer: The geotechnical engineer retained to provide necessary supplemental rockcry construction guidelines shall be a practicing geotechnical/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. 3.01.3 Responsibilitl: 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 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 completion are made. 3.01.5 Changes to Finished Product: Such changes include, but are not necessarily limited to, excavation of 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 subsurface water forced, directed, or otherwise caused to flow behind the rockery in any quantity. 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 hydroseeding 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 in height shall be periodically monitored during construction by the geotechnical engineer to verify the nature and quality of the materials being used are appropriate, that the construction 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 municipality, 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). All fills should be placed in thin lifts not exceeding ten inches in loose thickness. Each lift should be compacted to at least 90 percent of the maximum dry density, as determined by ASTM Test Method D-1557-78 (Modified Proctor), before any additional rill is placed and compacted. In -place density tests should be performed at random locations within each lift of the rill to verify this degree of compaction is being achieved. 3.01.9 Fill Construction and Reinforcement: There are two methods of constructing a fill against which to build a rockery. The first, which typically applies to rockerics 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. 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 construction of a competent near vertical fill face against which to build the rockery. For the higher rockeries the use of a geogrid or geotechnical 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 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. 3.01.10 Rockery Kevwav: The first step in rockery construction, after general site clearing and/or general 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. The 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 Kev,,vav and Rockery Drainaize: On completion of 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 equivalent 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 installed with sufficient gradient to initiate 'flow, and should.be.,connected to a positive and permanent discharge. Positive and permanent drainage should be considered to rnean an existing, or to be installed, sto rm 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. 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 serni-rectangular shape. Any rocks of basically r0tinded 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. 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 some 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 (Horizontal: - 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 construction. - 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 drainare filter shall be installed layer between the rear face of the rockery and the soil face being protected. This filt-er laver 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. 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 geotechnical 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 virtual impossibility 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 Drainat-,e: It is the owner's responsibility 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 toc of the wall. Use of other drainage control measures should be determined on a case -by -case basis by the gcolechnical engineer prior to bidding on the project. 9/26/88