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20050175.pdfP /ZI P f_//I I PERMIT EXPIRES USE PERMIT n CITY OF EDMONDS ZQN22� / NUMBER ;iL CONSTRUCTION PERMIT APPLICATION d0B )SITE/APT# ADDRESS ) t ) / C c�CLC/ OWNER NAME/NAME OF BUSINESS �,�' 1 T NNAME/SUBDIVISION NO. LO O. LID NO. Ix MAILING ADDRESS 1 �� LID FEE $ W tESCP. Approved [] /'� PUBLIC RIGHT OF WAY PER OFFICIAL STREET MAP RW Permit Required D l) ' Street Use Permit Roq'd EXISTING PROPOSED Inspection Required p CITY ZIP TELEPHONE Sidewalk Required Q 22 REQUIRED DEDICATION FT underground rend � � ` , / / Widnrg required 4 NAME METER SIZE LINE SIZE NO. OF FIXTURES PRV REQUIRED W �G.. ` G L` C� t -t Cott,� .. P / it / tt Q? YES ❑ NO 13E ADDRESS REMARKS J `//� (-1� OWNER/CONTRACTOR RESPONSIBLE FOR EROSION CONTROUDRAINAGE CITY_ I a ZIP TELEPHONE / r 5 �^ ` a 7, N&IME CBL # C, -t ,h l ow ADDRESSo o I� CITY I ZIP TELEPHONE Moil 11 Vim,, .7 V Ii 11F STATE LICENSE NUMBER EXPIRATION DATE CHECKED BY cjp� ITaT06T jP _gQ bi o6l PROPERTY TAX ACCOUNT PARCEL NO. 10 co NEW C RESIDENTIAL 9 PLUMBING / MECH ❑ ADDITION COMMERCIAL COMPLIANCE OR ❑ ❑ CHANGE OF USE ❑ REMODEL ❑ MULTIFAMILY ❑ SIGN FENCE ❑ REPAIR CYDS ❑ ( X FT) ❑ DEMOLISH ❑ TANK ❑ OTHER GARAGE RETAINING WALL FIRE SPRINKLER _ ARPORT ❑ ROCKERY ❑ FIRE ALARM (rYPE OF USE, BUSINESS OR ACTNnY) EXPLAIN: icV GNUMBER NUMBER OF CRITICAL OF DWELLING AREAS J� p STORIES UNITS NUMBER 1 DESCRIBE WORK TO BE DONE 1n +.,1 �nWAr6k /J'/ Fa F'7,�Ft N91. EERING REVIEWED BYDATE y tel^ �/3 10 14t4v'/ / fi6 /�Llg( 'V !� ofIRE REVIEWED BY DATE ¢ Z ai p 1VijAN�I� CIYjv(9 �t ORELINE OR ADB# INSPECTION BOND n T O , REQA POSTED 71 ❑YES 0 S SEPA REVIEW SIGN AREA HEIGHT 9 COMPLETE EXEMPT ALLOWED PROPOSED ALLOWED PROPOSED WX EXP . S i ❑ M LOT COVERAGE REQUIRED SETBACKS (FT.) PROPOSED SETBACKS (FT) C ALLOWED PROPOSED FRONT SIDE REAR FRONT UR SIDE R M 15t1 i2 .s ' lo' 2T ` 10' ip' ` z 0 C KINGLOT AREA PLANNING REVIEWED BY DATE S REQ'D PROVIDED Z1 a m 2 .y i12414;37$g' p Z S" I Y.:� r I ,� C Tz AM ix or PP a , �oyOP �� , CH9 TYPE OF•C N TRUCTION CODE OCCUPANT [y�/ GROUP X m SPECIAL INSPECTION JAREA OCCUPANT O N REQUIRED E3 l-1%?,Y,� LOAD t7 C N REMARKS PROGRESS INSPECTIONS PER UBC 108/IBC109/IRC109FINAL INSPECTION REO'D S i r m CO) �r VALUATIOND "'0""d1�t1� /P�QX33 $ ��t5 %D� '" r7 37 -, OPPPPP 51 C _ADescription FEE Description FEECD _ _J Z Plan Check Lj� State Surcharge �I P, P HEATSOURCE GLAZING % OPE 11 r� V City Surcharge 0Building Permit PLA EC VESTED DATE m Plumbing t, Base Fee/"" '� Mechanical e THIS PERMIT AUTHORIZES ONL THE WORK NOTED. THIS PERMIT COVERS WORK TO t BE DONE ON PRIVATE PROPERTY ONLY, ANY CONSTRUCTION ON THE PUBLIC 'i 7 DOMAIN (CURBS, SIDEWALKS, DRIVEWAYS, MARQUEES, ETC.) WILL REQUIRE Grading ;� SEPARATE PERMISSION, 2 Engr, Review W PERMIT APPLICATION: 180 DAYS d PERMIT LIMIT, 1 YEAR - PROVIDED WORK IS STARTED WITHIN 180 DAYS Engr, Inspection / SEE BACK OF PINK PERMIT FOR MORE INFORMATION a 'APPLICANT, ON BEHALF OF HIS OR HER SPOUSE, HEIRS, ASSIGNS AND SUCCESORS Flf@ Review Plan Chk. Deposit4N7 7 IN INTEREST, AGREES TO INDEMNIFY, DEFEND AND HOLD HARMLESS THE CITY OF _ ff 2 EDMONDS, WASHINGTON, ITS OFFICIALS, EMPLOYEES, AND AGENTS FROM ANY AND Fire Inspection Receipt # ALL CLAIMS FOR DAMAGES OF WHATEVER NATURE, ARISING DIRECTLY OR INDIRECTLY i FROM THE ISSUANCE OF THIS PERMIT. ISSUANCE OF THIS PERMIT SHALL NOT BE Landsca a lns Total Amt. Due 9 DEEMED. TO MODIFY, WAIVE OR REDUCE ANY REQUIREMENT OF ANY CITY ORDINANCE P p• '> -�• `� s NOR LIMIT IN ANY WAY THE CITY'S ABILITY TO ENFORCE ANY ORDINANCE PROVISION.' i Recording Fee Receipt # I HEREBY ACKNOWLEDGE THAT I HAVE READ THIS APPLICATION; THAT THE INFORMATION APPLICATION APPROVAL [GIVEN IS CORRECT; AND THAT I AM THE OWNER, OR THE DULY AUTHORIZED AGENT OF d is not a permit until signed by the Buil THE OWNER. I AGREE TO COMPLY WITH CITY AND STATE LAWS REGULATING CONSTRUC- CALL This application TION; AND IN DOING THE WORK AUTHORIZED THEREBY, NO PERSON WILL BE EMPLOYED ding Oliicial or his/her Deputy: and Fees are paid, and IN VIOLATION OF THE LABOR CODE OF THE STATE OF WASHINGTON RELATING TO FOR INSPECTION raceipt is acknowledged in space provided. i WORKMEN'S COMPENSATION INSURANCE AND RCW 18.27, DATE OFFICIALS SIGN URE TURE (OWNER O AGE DATE SIGNED (425)� r � �\ dLUID 11 - L 771 0220 RE ASED BY / jDfE ENTtON EXT 1333 IT I UNLAWFULTO USE OR OCCUPYABUILDING OR STRUCTURE UNTILAFINAL t / INSPECTION HAS BEEN MADE AND APPROVAL ORA CERTIFICATE OFOCCU- ORIG14 FILE YELLOW -INSPECTOR PANCY HAS BEEN GRANTED, UBC109 / IBC110 / IRC110. PINK • wNER GOLD -ASSESSOR 09/03 PRESS HARD -YOU ARE MAKING 4 COPIES dad - 1 -IDZA r DD 3 Dw 110wI p ti z 0 pain 0 y 0< u n" A°1 YIx m� r� OU 0 t• as .p' 0�1c (�D A Om <p �r�N lJflmp i �z a Ar In N�IO D1 rn 9 A r Q N D D� y rnu 1In p; n A In �dYN? 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T a AFASn ri .{Aaf.0 tn L �3QA2�2 n In n 70 . _ - (✓ -In G inhn UAiztp KiFn k _ NYI1� R1 OPSC o40 m$ va E3 M v' O N O- ~ 1. r: 0 U Q Protect, 11644 N.E. 80th Street v :V 7. < 0 4 - - KlrAland, r^w. >\ 3 o GRITGHLOW RLSII�GNGC 99033-9111 h1( ^+ TQ. u a n g305 OLYMPIC VIEW DRIVE NASII,rJONFS (425) 829-4119 E17M01`iDS..WA. ANDERSON 9101 5YrRd. a to 50=214J r Tualatin, OR ♦7 0 99062 Geotechnical Report Critchlow Homes — Single -Family Residence Edmonds, Washington February 15, 2005 C1< ' CG File No. 1801 t; Page 2 You plan to construct asingle-family residence with a patio and concrete step. The water feature has been eliminated from the planned improvement. You have asked us to provide our geotechnical opinions regarding the steep slope and the impact to slope stability of the planned patio and steps as specified in IBC 1802. �` ;. n. ; .. SCOPE C . The purpose of our services was to evaluate site conditions and to provide recommendations forrn ;; development. Our scope of services included the following: m 0 O ,..•A On �•t 1. Review available geologic maps and geotechnical reports for the site. -, rn Z 2. Explore subsurface conditions with shallow hand explorations 3. Provide an evaluation of the steep slope portion of the site. D 1 4. Provide recommendations for support of the planned foundations, including t recommendations for slope setbacks: 0 M O� 5. Provide recommendations for site preparation and grading. ` j 6. Prepare a report summarizing our conclusions and recommendations. rn0 N, .! O C F F C N ` SITE CONDITIONS i m n Zr ; Surface Conditions M' _. The site is an irregularly-shaped parcel with maximum dimensions of approximately 240 feet in 1 _, the east -west direction and 78.5. feet in the north -south direction. The site slopes gently down to z 1 St the west before reaching the top of a steep slope. Based on the provided site plan, there is an i ^-, elevation difference of approximately 12 feet between the east and west sides of the site in the ` building portion of the lot. A foundation remains where the old. house was demolished, but the n { m i remainder of the site was clear and free of vegetation. The west side of the site consists of a i bluff and a steep west -facing slope that slopes down to the Burlington Northern rail road tracks.` The bluff is approximately 130 feet in vertical relief with an average slope of 13 percent. We did not observe indications of surface water or silt layers, or slope movement, including the !, leaning of trees on the steep slope'at the time of our site visit on February 3, 20059 Cornerstone Geotechnical, Inc. r Geotechnical Report Critchlow Homes — Single -Family Residence Edmonds, Washington February. 15, 2005 ' ' CG File No. 1801 Page 3 Geology t' Most of the Puget Sound Region was affected by past intrusion of continental glaciation. The last period of glaciation, the Vashon Stade of the Fraser. Glaciation, ended approximately 10,000 to �+ 11,000 years ago. Many of the geomorphic features seen today are a result of scouring and Lr overriding by glacial ice. During the Vashon Stade; the Puget Sound region was overridden by m. ' over 3,000 feet of ice. Soil layers overridden by the ice sheet were compacted to a much greater -q Mn extent than those that were not. N i. C M O M ,.. N. The geology of the site is shown on the Preliminary Surficial Geolo 'c Map of the Edmonds East 00 r and Edmonds West Quadrangle Snohomish and King Counties, Washington, Mackey Smith, ic .�, m M 1975. The geologic unit mapped in the project is the Whidbey Formation (Qw). Transitional p i; rt C Z Beds consists of a clay, silt and fine to very fine sand. The Whidbey Formation is older than the ' Transitional Beds and generally consists of cross-bedded sand deposits, and also silts. While our O j explorations did encounter Whidbey Formation, we expect these soils core most of the hillside. 0 We encountered sand deposits that appear to be advance outwash. The outwash has been m m IL compacted by the weight of the glacier. 0N n 4 Explorations i . m n Subsurface conditions were explored at the site on February 3, 2005, by excavating a total of four M hand augers. Hand augers were excavated to depths ranging between 3.0 and 5.2 feet below the . ground surface. The explorations were located in the field by a representative from this firm who } z kr also examined the soils and geologic conditions encountered, and maintained logs of the hand '. 1 augers. The approximate locations of the hand augers are shown on the Site Plan in Figure 2. OZ - The soils were visually classified in general accordance with the Unified SoilClassification 0 —' System, a copy of which is presented as Figure 3.. The logs of the hand augers are presented in m Figure 4. Lr Subsurface Conditions { We encountered a sand with gravel and silt in our explorations underlying the topsoil layers.: We expect the Whidbey Formation silt underlies the sand deposit. Specific soil conditions can be L�s viewed in our soil logs. Lf , Cornerstone Geotechnical, Inc. { e' Geotechnical Report Critchlow Homes - Single -Family Residence Edmonds, Washington February 15, 2005 CG File No. 1801 Page 4 Hydrologic Conditions ; Shallow ground water seepage was not encountered in our explorations. The dense . soil r. interpreted to underlie the site is considered poorly draining. During the wetter times of the year, z' 0 we expect perched water conditions will occur within the upper sand on top of the dense soil. n; M 4; layer. Perched water does not represent a regional ground water "table" within the. upper soil horizons. Volumes of perched ground water vary depending upon the time of year and the j N k'.. upslope recharge conditions. C M ;CD:: m-10iF v Seismic Hazard 0 c -..;, The site is classified based on its overall soil profile using Table 1615.1.1 of the 2003 = rn z'" M S' International Building Code .(IBC). Site conditions best fit the IBC definition for Site Class C C D Z ("Very dense soil and soft rock"). The IBC provides parameters and coefficients to be used in ` Ca,. seismicdesign, based upon this site class. O M Additional seismic considerations include liquefaction potential and amplification of ground ; m m G IIe motions by soft soil deposits. The liquefaction potential is highest for loose sand with a high i g ;?,, ! ground water table. The underlying dense soils are .considered to have a very low potential for Z N i liquefaction and amplification of ground motion. a JZ n SLOPE STABILITY The core of the site is inferred to be comprised of advance outwash underlain by the Whidbey t Formation. We .did not be signs of deep-seated slope failures. We did. observe one CO; r. indication of a shallow surface failure on the slope. This is the typical shallow failure that occurs O on these types of bluffs. We expect most of the shallow failures would be less than 10 feet thick, C� M but based on the history along this. bluff of Puget Sound, this distance could be more. For this reason, building setback recommendations have been provided in this report. CONCLUSIONS AND RECOMMENDATIONS F General he underl It is our opinion that the site is compatible with the planned development. T yin g ". medium dense or better soils are capable of providing adequate support for the proposed `. Cornerstone Geotechnical, Inc. Geotechnical Report Y - Critchlow Homes - Single -Family Residence Edmonds, Washington February 15, 2005 rF CG File No. 1801 Page 5 structures. We recommend that the foundations for the structures extend through any water ' loosened or disturbed soils, and.bear on medium dense or better native soils,, or on structural fill extending to these soils. We anticipate that these soils will generally be encountered at typical j ZO { footing depths. n The soils likely to be exposed during construction may be moisture sensitive and will disturb t: , easily when wet. We recommend that construction take place during the drier summer months. co � Rt is If construction takes place during the wet season, additional expenses and delays should be a_ n is ' expected due to the wet conditions. Additional expenses could include the need to place a p C fti; j blanket of rock in the footing areas to minimize disturbance to the prepared footing subgrade: D Z S?: Building Setbacks r ; Uncertainties related to building along the top of steep slopes and, in particular, unstable or , p "n _.; actively backwasting slopes, are typically addressed by the use of building setbacks. The purpose on M !. of the setback is to establish a "buffer zone" between the structure areas and the top of the slope m m so that ample room is allowed for normal slope recession during a reasonable life span of the p.u� Fn { structure (usually taken to be 50 to 100 years): In a general sense, a greater setback will result in C a lower risk to. the structures. From a geological standpoint, the setback dimension is based on } Z T� i. the slope's physical characteristics, such as slope height,surface angle, material composition, and x. hydrology. Other factors, such as historical slope activity, rate of regression, and the type and desired life span of the development, are important considerations as well.. } Z The planned building should be located at least 30 feet back from the top of the slope. The Z building could be located closer to the slope, but. the foundations would need to extend, deeper n into the hillside. The patio slab and steps may be located no closer than 15 feet from the slope. m The steps are considered a non-critical structure and.could be removed if the slope recedes. We recommend that no significant fill be placed within 30 feet of the west slope without a specific geotechnical review. We are available to consult with you on the amount of fill - acceptable. j . Cornerstone Geotechnical, IncI Id. r: , Geotechnical Report Critchlow Homes — Single -Family Residence Edmonds, Washington February 15, 2005 CG File No. 1801 Page 6 Structural Fill General: We do not expect a significant amount of fill will be placed on site. However, all fill ; placed beneath buildings, pavements or other settlement sensitive features should be placed as O t structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and standards, and is monitored by an experienced geotechnical professional or soils technician. rn Field -monitoring procedures would include the performance of a representative number of in Met mini CO lace density tests to document the attainment of the desired degree of relative compaction, v m k p Ic rn 0 : Materials: Imported structural fill should consist of a good quality, free -draining granular soil, 0 OC ` free of organics and other deleterious material, and be well graded to a maximum size of about 3 rnif M i inches. Imported, all-weather structural fill should contain no more than 5 percent fines (soil Q -� i. finer than a Standard U.S. No. 200 sieve), based. on that fraction passing the U.S. 3/4 -inch sieve.CD _ i omn The use of on-site soil as structural fill will be dependent on moisture content control. Some .n 90 i drying of the native soils may be necessary in order to achieve compaction. During warm, .sunny M M ' ' rn rn days this could be 'accomplished by spreading the material in thin lifts and compacting. Some , .: 0 va 0 Fn f'3 i aeration and/or addition of moisture. may also be necessary. We expect that compaction of the C (0 i fications would be difficult, if not impossible, during wet t Z native soils to structural fill speci weather. I Fill Placement: Following subgrade preparation, placement of the structural fill may proceed. D ;' Z, Fill should be placed in 8- to 10 -inch -thick uniform lifts, and each lift should be spread evenly. _ . and be thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying Z building areas; and within a depth of 2 feet below pavement and sidewalk subgrade, should be O com acted to at least 95 percent of its maximum dry density. Maximum' dry density, in this m p report; refers to that density as determined by the ASTM D 1557 compaction test procedure. Fill more than 2 feet beneath sidewalks and pavement subgrades should be compacted to at least 90 percent of the maximum dry density. The moisture content of the soil to be compacted should be within about 2 per of optimum so that a readily compactable condition exists. It may be �.: necessary to overexcavate and remove wet surficial soils in cases where drying to a compactable condition is not feasible. All compaction should be accomplished by equipment of a type and size sufficient to attain the desired degree of compaction. c. Cornerstone Geotechnical, Inf Geotechnical Report Critchlow Homes — Single -Family Residence i �.. Edmonds, Washington February 15, 2005 CG File No. 1801 Page 7 Temporary and. Permanent Slopes Temporary cut slope stability is a function of many factors, such as the type and consistency of soils, depth of the cut, surcharge. loads adjacent to the excavation, length of time a cut remains Z -" open, and the presence of surface or groundwater. It is exceedingly difficult under these variable n M ' conditions to estimate a stable temporary cut slope geometry, Therefore, it should be the i Mn}.'. responsibility of the contractor to maintain safe slope. configurations, since the contractor is i _ { continuously at the job site, able to observe the nature and condition of the cut slopes, and able toC m monitor the subsurface materials and ground water conditions encountered. O OC # XM For planning purposes, we recommend that temporary cuts in the near -surface weathered soils m Z ,T and outwash be no greater than 1.5 Horizontal to I Vertical (1.5H:1V). Cuts in the dense C Z i unweathered soils may stand at a 0.75H: IV inclination or possibly steeper. If ground water ca rIr ' a e is encountered, we would expect that flatter inclinations would be necessary. p seepage i r _ We recommend that cut slopes be protected from erosion, Measures taken may include covering m m O C4 j cut slopes with plastic sheeting and diverting surface runoff away from the top of cut slopes. We O j 1 0 Fn IF do not recommend vertical slopes for cuts deeper than 4 feet, if worker access is necessary. We i j recommend that cut slope heights and inclinations conform to local and WISHA/OSHA r ; standards. d - Final slope inclinations for structural fill and the cuts in the native soils -should be no steeper than Z f, 2H: IV, Lightly compacted fills or common fills should be no steeper than 3H: IV. Common fills are defined as fill material with some organics that are "trackrolled" into place. They would not Oz meet the compaction specification of structural fill. Final slopes should be vegetated and covered 0 with straw or jute netting, The vegetation should be maintained until it is established. m Foundations Conventional shallow spread foundations should be founded on undisturbed, medium dense to glacial soils, or be supported on structural fill extending to those soils. If the soil at + very dense, g Pp g ;, . the planned bottom of footing elevation is not medium dense to very dense, it should be f overexcavated.to expose suitable bearing soil, and the excavation should be.filled with structural �+ fill, or the footing may be overpoured with extra concrete. i Cornerstone Geotechnical, Inc, J r Geotechnical Report Critchlow Homes — Single -Family Residence Edmonds, Washington February. 15, 2005. CG File No. 1801 Page 8 €.n. Footings should extend at least 18 inches below the lowest adjacent finished ground surface for !' frost protection and bearing capacity considerations. Minimum foundation widths of 16 and 20 pi ` inches should be used for continuous and isolated spread .footings, respectively. Standing water Z should not be allowed to accumulate in footing trenches. All loose or disturbed soil should be m removed from the foundation excavation prior to placing concrete. For foundations constructed as outlined above, we recommend an allowable design bearing us C m pressure of 2,000 pounds per square foot (psf) be used for the footing design. International m v o; Building Building Code (IBC) guidelines should be followed when considering short-term transit ory.wind p C K; or. seismic loads. Potential foundation settlement using the recommended allowable bearing = rn '. — pressure is estimated to be less .than 1 -inch total and 1/2 -inch differential between footings or C '� - D Z across a distance of about 30 feet. Higher soil bearing values may be appropriate for footings r founded onthe unweathered drift/till, and with wider footings. These higher values can be N 1` � T. determined after a review of a specific design. I m rnrn ,. Lateral loads can be resisted by friction between the foundation and subgrade soil, and by passive soil resistance acting on the below -grade portion of the foundation. For the latter, the foundation c N ca must be poured "neat".against undisturbed soil or backfilled with clean, free -draining, compacted n structural fill. Passive resistance may be calculated as a triangular equivalent fluid pressure distribution. We recommend that an equivalent fluid density of 225 pounds per, cubic foot (pcf) Ilk be used to calculate the allowable lateral passive resistance for the case of a level ground surface Z t adjacent to the footing. An allowable coefficient of friction between footings and soil of 0.45 `.. may be used, and should be applied to the vertical dead load only. A factor of safety of 2.0 has 0 been applied to the passive pressure to account for required movements to generate these n m : --. pressures. The friction coefficient does not include a factor of safety. is Slabs -On -Grade Slab -on -grade areas should be prepared as recommended in the Site Preparation and Grading subsection. Slabs should be supported on medium dense to very dense native soils, or on structural fill extending to these soils. Where moisture control is a concern, we recommend that slabs be underlain by 6 inches of free -draining coarse sand or pea gravel for use as a capillary Cornerstone Geotechnical, Inc. G r Geotechnical Report Critchlow Homes - Single -Family Residence .., Edmonds, Washington February 15, 2005 t . CG File No. 1801. Page 9 break. A suitable vapor barrier, such as heavy plastic sheeting, should be placed over the . capillary break. 0 i Drainage " 0 Surface m We recommend that runoff from impervious surfaces, such as roofs, driveway and accessca roadways, be collected and routed to an appropriate storm water discharge system. Final site rn•, grades. should allow for drainage away from any buildings. We suggest that the finished ground M 0 d surface be sloped at a gradient of 3 percent minimum for a distance of at least 10 feet away from 0. C << ..» C the buildings. Surface water should be collected by permanent catch basins and drain lines, and m rn c g be discharged into a storm drains stem. — y y z We recommend yard drains be placed in strategic locations to collect surface water flowing from N O I ? the impervious patio and stairs. It is important that these drains function and are periodically maintained. It is best if all surface runoff should be directed away from the steep slope and into M m j:,, storm drains. 0 i ._ nF . E' c v, n Subsurface We recommend that footing drains be used around all of the structures where moisture control is M important. The underlying soils may pond water that could accumulate in the crawl space. It is f . good practice to use footing drains installed at least 1 foot below the planned finished floor slab ` z or crawl space elevation to provide drainage for the crawl space. At a minimum, the crawl space CO should be sloped to drain to an outlet tied to the drainage system. If drains are omitted around O slab -on -grade floors where moisture control is important, the slab should be a minimum of 1 foot 0 . M. above surrounding grades. Where used, footing drains should consist of 4 -inch -diameter, perforated PVC pipe that is surrounded by free -draining material, such as pea gravel. Footing drains should discharge into ; tightlines leading to an appropriate collection and discharge point. Crawl spaces should be sloped to drain, and a positive connection should be made into the foundation drainage system. For slabs -on -grade, a drainage path should be provided from the capillary break material to theI Id footing drain system. Roof drains should not be connected to wall or footing drains. Cornerstone Geotechnical, Inc. t r. Geotechnical Report Critchlow Homes — Single -Family Residence Edmonds, Washington is February 15, 2005 CG File No. 1801 id Page 10 Pavement 4JP The performance of roadway pavement is critically related to the conditions of the underlying subgrade. We recommend that the subgrade soils within the roadways be treated and prepared as iv- described in the Site Preparation and Grading subsection of this report. Prior to placing base material, the subgrade soils should be compacted to a non-yielding state with a vibratory roller m s - compactor and then proof-rolled with a piece of heavy construction equipment, such as a fully- loaded dump truck. Any areas with excessive weaving or flexing should be overexcavated and - dM r.. recompacted or replaced with a structural fill or crushed rock placed and compacted in m'O s r ' accordance with recommendations provided in the Structural Fill subsection of this report. O:C:;: = rn �. m. Z F k A l . - MONITORING a z We should be retained to provide monitoring and consultation services during construction toCA . confirm that the conditions encountered are consistent with those indicated by the explorations, i� and to provide recommendations for design changes, should the conditions revealed during the MM ? i work differ from those anticipated. As part of our services, we would also evaluate whether or N 4 1.111 not earthwork and foundation installation activities comply with contract plans and specifications. C i _V1, t ' Q0 I USE OF THIS LETTER Id We have prepared this letter for Critchlow Homes, Inc. and its agents, for use in planning and design of this project. Our services were performed to evaluate the presence of perched ground Z water and provide an estimate of the rate of flow of the ground water } '' s Within the limitations of scope, schedule and budget for our work, we have strived to take care O' our work has been completed in accordance with generally accepted practices followed in this rn area at the time this letter was prepared: No other conditions, expressed or implied, should be understood. r .a i 000 I t. Cornerstone Geotechnical, Inc. W A i . ��----•, ..—.__._. Tom.._ .— .o.......aa uwt+•,a a+a 4sikfrii4�k', 6�+i:fNwo S1 +Ni1 prepw�Yp low am ......._. _..... _....: _. _ ..._. ......... _...... 11.1ftfe.:.._ ..........._ _.........1.11,We. a.............................._._........................_.._...... Site Plan �p Alk .4%We / rr3''50'22I'veft" _ c i ,. CC T1116 .X� t'i I rp r � \�G` N V1 fteae • .c w 7 ! ' .I :may HA-2 I - HA-1 I nof I Lj t; 1 a al { ftede No., HA4 00 46 36 i ,1... ..''•. rOQ+�'r ,1. •ifr'4P;S t� ^1s�ir '�•�.L?"7�c^ � I� � . • • j �), r .ra' flay[- � Id lam. 2 ,3 a�; 5 =15a:; Unified Soil Classification System w., GROUP MAJOR DIVISIONS SYMBOL GROUP NAME GRAVEL CLEAN GRAVEL GW WELL -GRADED GRAVEL, FINE TO COARSE GRAVEL •�.+ COARSE,,, GRAINED MORE THAN 50% OF GP POORLY -GRADED GRAVEL COARSE FRACTION SOILS RETAINED ON NO, GRAVEL GM SILTY GRAVEL SIEVE WITH FINES Z {' GC CLAYEY GRAVEL O MORE THAN 50% m RETAINED ON SAND CLEAN SAND SW WELL -GRADED SAND, FINE TO COARSE SAND number 200 SIEVE - SP POORLY -GRADED SAND MORE THAN 50% OF 0 m,_ COARSE FRACTION SAND fC� C) PASSES NO.4 SIEVE WITH FINES SM SILTY SAND O O 0 C { SC CLAYEY SANDm ,. mz SILT AND CLAY INORGANIC ML SILT C Z FINE - a > GRAINED LIQUID LIMIT CL CLAY LESS THAN 50% y 0 'n SOILS ORGANIC ; [ OL ORGANIC SILT, ORGANIC CLAY M m y MORE THAN 50% 0 N i ' PASSES N0.200 SIEVE SILT AND CLAY INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT O _ CN G C co LIQUID LIMIT CH CLAY OF HIGH PLASTICITY, FAT CLAY is I 50% OR MORE (�, ORGANIC OH ORGANIC CLAY, ORGANIC SILT I t HIGHLY ORGANIC SOILS PT PEAT r Z NOTES: SOIL MOISTURE MODIFIERS ; CO), t 1,11 1) Field classification is based on Dry -Absence of moisture, dusty, dry � visual examination of soil in general to the touch m, accordance with ASTM D 2488-83, 2) Soil classification using laboratory Moist- Damp, but no visible water11 14 tests is based on ASTM D 2487-83. Wet- Visible free water or saturated, 3) Descriptions of soil density or usually soil is obtained from consistency are based on below water table interpretation of blowcount data, I visual appearance of soils, and/or test data. (I COr11@rSt011@ Phone: (425) 844-1977 Unified Soil Classification System Fax: (425) 844-1987 Geotechnical, Inc. 17625 -130th Ave NE, C-102 • Woodinville, WA• 98072 Figure 3 i l ;i LOG OF EXPLORATION per" DEPTH USC SOIL DESCRIPTION HAND AUGER ONE j 0.0 - 2.4 ML BROWN SANDY SILT WITH ROOTS, GRAVEL (LOOSE, WET)TO( PSOIL) 2.4-3.7 ML REDDISH -BROWN SANDY SILT WITH GRAVEL, TRACE ROOTS AND ORGANICS (LOOSE, MOIST) {' i 3.7-4.2 SM BROWNISH -GRAY SILTY FINE TO MEDIUM SAND WITH GRAVEL (MEDIUM DENSE,' MOIST) Z O 5 4.2 - 4.8 SW -SM GRAY FINE TO COARSE SAND WITH GRAVEL AND SILT (MEDIUM DENSE, MOIST) 01 4.8 - 5.2 SP GRAY MEDIUM TO COARSE SAND WITH GRAVEL TO COBBLES (MEDIUM DENSE TO m DENSE, WET) , SAMPLES WERE COLLECTED AT 1 o0 2.4, 3.7, 4.2, AND 4,8 FEETco GROUND WATER SEEPAGE WAS NOT ENCOUNTERED r=11 TEST HOLE CAVING WAS NOT ENCOUNTERED ii HAND AUGER WAS COMPLETED AT 5.2 FEET ON 2/3/05 rn 0 1 O r HAND AUGER TWO a O C 0.0-2.3 ML BROWN TO REDDISH -BROWN SANDY SILT WITH ROOTS, GRAVEL, AND ORGANICS m Y` A (LOOSE, WET) (TOPSOIL) m Z 263-41 ML BROWNISH -GRAY SANDY SILT WITH GRAVEL (LOOSE TO MEDIUM DENSE, MOIST) D Z ., I 4A 4.5 SM GRAY SILTY FINE TO COARSE SAND WITH GRAVEL TO COBBLES (MEDIUM DENSE, � N h,: I WET) 1r SAMPLES WERE COLLECTED AT 1.8, 2.31 AND 4.1 FEET m m =` 3 GROUND WATER SEEPAGE WAS NOT ENCOUNTERED TEST HOLE CAVING WAS NOT ENCOUNTERED r cn {-- HAND AUGER WAS COMPLETED AT 4.1 FEET ON 2/3/05 rr 0m t . HAND AUGER THREE Ca t Zrm 0.0 - 2.2 SM DARK BROWN SANDY SILT WITH GRAVEL (LOOSE, MOIST) (TOPSOIL) 2.2 - 5.0 SW -SM BROWNISH -GRAY SANDY SILT WITH GRAVEL AND SILT (LOOSE, MOIST) 5.2 - 5.4 SP GRAY MEDIUM TO COARSE SAND WITH GRAVEL TO COBBLES (MEDIUM DENSE, MOIST) Z s, ; 1 , SAMPLES WERE COLLECTED AT 2.59 3.5 AND 5.0 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED _ TEST HOLE CAVING WAS NOT ENCOUNTERED Z HAND AUGER WAS COMPLETED AT 5.4 FEET ON 2/3/05 O HAND AUGER FOUR 1 0M 0.0 -1.6 ML BROWN SANDY SILT WITH ROOTS AND GRAVEL (LOOSE, MOIST) (TOPSOIL) 7 1.6 - 2.3 ML LIGHT BROWN SANDY SILT TRACE GRAVEL (LOOSE , MOIST) t 2.3-3.6 SM GRAY TO BROWNISH -GRAY SILTY FINE TO MEDIUM SAND WITH GRAVEL (MEDIUM I DENSE, MOIST) ' 16-18 SP -SM GRAY FINE TO MEDIUM SAND WITH SILT AND GRAVEL TO COBBLES (MEDIUM DENSE, MOIST SAMPLES WERE COLLECTED AT 0.5, 1.79 2.3 AND 3.6 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED r- TEST HOLE CAVING WAS NOT ENCOUNTERED - HAND AUGER WAS COMPLETED AT 3.8 FEET ON 2/3/05 CORNERSTONE GEOTECHNICAL, INC. FILE NO 1801 i __ FIGURE 4 j IMPOP1801 Infop'Matolon About YOUP Geolechumical Engineeping Repopt Subsurface III' e a principal causeof / I delays,I overruns,and disputes. Z , 0 • following information is provided I help you manage your risks. M rn coy= vm Geotechnical Services Ape Pepfolrmed fop elevation, configuration, location, orientation, or weight of the fn v Specific Pupposes, Persons, and Ppojects proposed structure; 0 n Geotechnical engineers structure their services to meet the specific needs of composition of the design team, or .� K their clients. A geotechnical engineering study conducted for a civil engi- project ownership.m Z neer may not fulfill the needs of a construction contractor or even another D civil engineer, Because each geotechnical engineering study is unique, each As a general rule, always inform your geotechnical engineer of project a Z geotechnical engineering report is unique, prepared solelyfor the client. No changesevenminor ones—and request an assessment of their impact. r = one except you should rely on your geotechnical engineering report without Geotechnical engineers cannot accept responsibility or liability for problems N I first conferring with the geotechnical engineer who prepared it. And no one that occur because their reports do not consider developments of which O "n ' — not even you —should apply the report for any purpose or project they were not informed. except the one originally contemplated, m rn Subsupface Conditions Can Change Vi Read the Full Repollrt A geotechnical engineering report is based on conditions that existed at O Serious problems have occurred because those relying on a geotechnical the time the study was performed. Do not rely on a geotechnical engineer- c N engineering report did not read it all. Do not rely on an executive summary. Ing report whose adequacy may have been affected by: the passage of C CO)- Do not read selected elements only. time; by man-made events, such as construction on or adjacent to the site; r Z or by natural events, such as floods, earthquakes, or groundwater fluctua- A Geotechnical Engineering Report Is Based on tions. Always contact the geotechnical engineer before applying the report X A Unique Set of Project -Specific Factors to determine if it is still reliable: A minor amount of additional testing or awl Geotechnical engineers consider a number of unique, project -specific fac- analysis could prevent major problems. D tors when establishing the scope of a study. Typical factors include: the ► client's goals, objectives, and risk management preferences; the general Most Geotechnical Findings Are Professional nature of the structure involved, its size, and configuration; the location of Opinions the structure on the site; and other planned or existing site improvements, Site exploration identifies subsurface conditions only at those points where I p such as access roads, parking lots, and underground utilities. Unless the subsurface. tests are conducted or samples are taken. Geotechnical engi- geotechnical engineer who conducted the study specifically indicates oth- neers review field and laboratory data and then apply their professional m erwise, do not rely on.a geotechnical engineering report that was: judgment to render an opinion about subsurface conditions throughout the • not prepared for you, site. Actual subsurface conditions may differ -sometimes significantly— not prepared for your project, from those indicated in your report. Retaining the geotechnical engineer • not prepared for the specific site explored, or who developed your report to provide construction observation is the • completed before important project changes were made. most effective method of managing the risks associated with unanticipated conditions, Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: A Repopt's Recommendations Are Not Final • the function of the proposed structure, as when it's changed from a Do not overrely on the construction recommendations included in your parking garage to an office building, or from a light industrial plant report. Those recommendations are not final, because geotechnical engi- to a refrigerated warehouse, neers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical have led to disappointments, claims, and disputes. To help reduce the risk engineer who developed your report cannot assume responsibility or of such outcomes, geotechnical engineers commonly include a variety of liability for the report's recommendations if that engineer does not perform explanatory provisions in their reports. Sometimes labeled "limitations" construction observation, many of these provisions indicate where geotechnical engineers' responsi- bilities begin and end, to help others recognize their own responsibilities A Geotechnical Engineering Report Is Subject to and risks. Read these provisions closely. Ask questions. Your geotechnical Misinterpretation engineer should respond fully and frankly. Other design team members' misinterpretation of geotechnical engineering reports has resulted in costly problems. Lower that risk by having your geo- Geoenvironmental Concerns Are Not Covered technical engineer confer with appropriate members of the design team after The equipment, techniques, and personnel used to perform a geoenviron- submitting the report. Also retain your geotechnical engineer to review perti- mental study differ significantly from those used to perform a geotechnical nent elements of the design team's plans and specifications. Contractors can study. For that reason, a geotechnical engineering report does not usually also misinterpret a geotechnical engineering report. Reduce that risk by relate any geoenvironmental findings, conclusions, or recommendations; having your geotechnical engineer participate in prebid and preconstruction e.g.,.about the likelihood of encountering underground storage tanks or conferences, and by providing construction observation. regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own geoen- Do Not Redraw the Engineer's logs vironmental.information, ask your geotechnical consultant for risk man Geotechnical engineers prepare final boring and testing logs based upon agement guidance. Do not rely on an environmental report prepared for. their interpretation of field logs and laboratory data..lo prevent errors or someone else. omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings. Obtain Professional Assistance To Deal with Mold Only photographic or electronic reproduction is acceptable, but recognize Diverse strategies can be applied during building design, construction, that separating logs from the report can elevate risk. operation, and maintenance to prevent significant. amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be Give Contractors a Complete Report and devised for the express purpose of mold prevention, integrated into a com- Guidance prehensive plan, and executed with diligent oversight by a professional Some owners and design professionals mistakenly believe they can make mold prevention consultant. Because just a small amount of water or . contractors liable for unanticipated subsurface conditions by limiting what moisture can lead to the development of severe mold infestations, a num-. they provide for bid preparation. To help prevent costly problems, give con- ber of mold prevention strategies focus on keeping building surfaces dry. tractors the complete geotechnical engineering report, but preface it with a While groundwater, water infiltration, and similar issues may have been clearly written letter of transmittal. In that letter, advise contractors that the addressed as part of the geotechnical engineering study whose findings report was not prepared for purposes of bid development and that the are conveyed in this report, the geotechnical engineer in charge of this report's accuracy is limited; encourage them to confer with the geotechnical project is not a mold prevention consultant; none of the services perm engineer who prepared the report (a modest fee may be required) and/or to formed in connection with the geotechnical engineer's study conduct additional study to obtain the specific types of information they were designed or conducted for the purpose of mold preven- need or prefer. A prebid conference can also be valuable. Be sure contrac- tion. Proper implementation of the recommendations conveyed tors have sufficient time to perform additional study. Only then might you in this report will not of itself he sufficient to prevent mold from be in a position to give contractors the best information available to you, growing in or on the structure involved. while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Rely, on Your ASFE-Member Geotechncial Engmeer for Additional Assistance Read Responsibility Provisions Closely Membership in ASFE[rhe Best People on Earth exposes geotechnical Some clients, design professionals, and contractors do not recognize that engineers to a wide array of risk management techniques that can be of geotechnical engineering is far less exact than other engineering disci- genuine benefit for everyone involved with a construction project, Confer plines. This lack of understanding has created unrealistic expectations that with you ASFE-member geotechnical engineer for more information. ASFE ' The lest reeole on Earth 8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone: 301/565-2733 Facsimile: 301/589-2017 e-mail: info@asfe.org www.asfe.org Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with ASFE's specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any other firm, individual, or other entity that so uses this document without being an ASFE member could be committing negligent or intentional (fraudulent) misrepresentation. IIGER06045.01d i subsurface conditions revealed during construction. The geotechnical have led to disappointments, claims, and disputes. To help reduce the risk engineer who developed your report cannot assume responsibility or of such outcomes, geotechnical engineers commonly include a variety of liability for the report's recommendations if that engineer does not perform explanatory provisions in their reports. Sometimes labeled "limitations" construction observation, many of these provisions indicate where geotechnical engineers' responsi- bilities begin and end, to help others recognize their own responsibilities A Geotechnical Engineering Report Is Subject to and risks. Read these provisions closely. Ask questions. Your geotechnical Misinterpretation engineer should respond fully and frankly. Other design team members' misinterpretation of geotechnical engineering reports has resulted in costly problems. Lower that risk by having your geo- Geoenvironmental Concerns Are Not Covered technical engineer confer with appropriate members of the design team after The equipment, techniques, and personnel used to perform a geoenviron- submitting the report. Also retain your geotechnical engineer to review perti- mental study differ significantly from those used to perform a geotechnical nent elements of the design team's plans and specifications. Contractors can study. For that reason, a geotechnical engineering report does not usually also misinterpret a geotechnical engineering report. Reduce that risk by relate any geoenvironmental findings, conclusions, or recommendations; having your geotechnical engineer participate in prebid and preconstruction e.g.,.about the likelihood of encountering underground storage tanks or conferences, and by providing construction observation. regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own geoen- Do Not Redraw the Engineer's logs vironmental.information, ask your geotechnical consultant for risk man Geotechnical engineers prepare final boring and testing logs based upon agement guidance. Do not rely on an environmental report prepared for. their interpretation of field logs and laboratory data..lo prevent errors or someone else. omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings. Obtain Professional Assistance To Deal with Mold Only photographic or electronic reproduction is acceptable, but recognize Diverse strategies can be applied during building design, construction, that separating logs from the report can elevate risk. operation, and maintenance to prevent significant. amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be Give Contractors a Complete Report and devised for the express purpose of mold prevention, integrated into a com- Guidance prehensive plan, and executed with diligent oversight by a professional Some owners and design professionals mistakenly believe they can make mold prevention consultant. Because just a small amount of water or . contractors liable for unanticipated subsurface conditions by limiting what moisture can lead to the development of severe mold infestations, a num-. they provide for bid preparation. To help prevent costly problems, give con- ber of mold prevention strategies focus on keeping building surfaces dry. tractors the complete geotechnical engineering report, but preface it with a While groundwater, water infiltration, and similar issues may have been clearly written letter of transmittal. In that letter, advise contractors that the addressed as part of the geotechnical engineering study whose findings report was not prepared for purposes of bid development and that the are conveyed in this report, the geotechnical engineer in charge of this report's accuracy is limited; encourage them to confer with the geotechnical project is not a mold prevention consultant; none of the services perm engineer who prepared the report (a modest fee may be required) and/or to formed in connection with the geotechnical engineer's study conduct additional study to obtain the specific types of information they were designed or conducted for the purpose of mold preven- need or prefer. A prebid conference can also be valuable. Be sure contrac- tion. Proper implementation of the recommendations conveyed tors have sufficient time to perform additional study. Only then might you in this report will not of itself he sufficient to prevent mold from be in a position to give contractors the best information available to you, growing in or on the structure involved. while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Rely, on Your ASFE-Member Geotechncial Engmeer for Additional Assistance Read Responsibility Provisions Closely Membership in ASFE[rhe Best People on Earth exposes geotechnical Some clients, design professionals, and contractors do not recognize that engineers to a wide array of risk management techniques that can be of geotechnical engineering is far less exact than other engineering disci- genuine benefit for everyone involved with a construction project, Confer plines. This lack of understanding has created unrealistic expectations that with you ASFE-member geotechnical engineer for more information. ASFE ' The lest reeole on Earth 8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone: 301/565-2733 Facsimile: 301/589-2017 e-mail: info@asfe.org www.asfe.org Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with ASFE's specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any other firm, individual, or other entity that so uses this document without being an ASFE member could be committing negligent or intentional (fraudulent) misrepresentation. IIGER06045.01d t PROJECT NUMBER 2336 26 July 1998 page 1 of 6 pages A CLIENT. James H. Murphy 9305 Olympic View Drive Edmonds, Washington 98020 m REFERENCE Stability of slopes for house placement ��—, z C 0 SUBJECT Geotechnical investigation o c im INTRODUCTION z CZ . The purpose of this report is to determine the potential slope lossCA present the results of a geotechnical during the lifetime of the proposed .0 study of. the stability of .the slopes houses in order to determine the .safe m M located at 9305 Olympic View Drive, locations of the houses relative to the o top of the slope. C N C� The property has been subdivided into z 0 parcels A and B; as shown in Figure 1. A The investigation. and report were 74 new house will be constructed on each authorized by James Murphy (owner) parcel.. The, existing house will be in a. letter dated 24 February 1998 z removed, and addressed to Dale C. Hemphill of i; HEMPHILL CONSULTING ENGINEERS ` 0)Z The purpose of the stability study is to (HEMPHILL). ° M INVESTIGATION • HEMPHILL had conducted a slope experienced the worst conditions in E investigation on the adjacent recorded history with the greatest % properties to the north of the site in rainfall for a 5 day period in February 1990. There is no evidence that any 1996, and the greatest number of significant sliding has occurred on slides in January 1997 from a those slopes in the past eight years, combination of melting slow (as much k even though Puget Sound has as 30 inches) and heavy rainfall. s N IMAJI� , rP i�i�i�L I, PROJECT NUMBER 2336 26 July 1998 page 2 of 6 pages { During that period many slides on their slopes for 15 or more years. occurred. on the slopes adjacent to Puget Sound in the vicinity of There was no evidence that any o Edmonds. Most of the slides were thin slides had occurred on the property to 0 rn sloughing (skin slides) of the outer the north in the past 10 years. Any weathered portion of the very hard slides were minor sloughing of theCo and strong glacially compacted soils weathered soils. There is a small spot v m C: that are. exposed in the slopes. Most on the Murphy property that exposes 0 of the slides included less than 2 feet glacial till that might have been the depth, and sometimes only .1 foot. result of a recent slide. Based on the p z Even under those extreme conditions Tack of evidence of slide debris on the a z less than 5%0 of the total slopes lower slope, that slough was very i actually had a thin slide. Any deeper minor. Because of the great strength o -Nn slides occurred in fill that had been of the slope. soils, a deep slide is placed on the slopes, or in areas that unlikely. The slope soils are known as o N had unusual conditions. According to Vashon Till, some owners slides had not occurred m zn DESCRIPTION of VASHON TILL Vashon Till is very dense, massive, The Vashon . Till was deposited i a: gray, and composed of various beneath the last glacier that occupied combinations of clay, silt, sand, and the Puget Sound area. That glacier. o gravel,4 with scattered cobbles and was estimated to. be 3000 to 4000 M boulders. The aggregates in Vashon feet thick in the Seattle area. The E Till are generally cemented together, heavy loads imposed by the glacier and they have a texture similar to (150,000 TO 200,000 PSF) concrete. Sometimes exposures of consolidated the Vashon Till to a very Vashon Till .have the appearance of dense, fairly impervious, very strong I. . concrete. soil. ` tf i ' NMI 14 am" PROJECT NUMBER 2336 26 July 1998 page 3 of 6 pages ' Undisturbed and unweathered Vashon eventually slough off. The depth of Till is difficult to excavate, and to a slough can range from a few inches to , pick and shovel it feels like concrete, a few feet. Each slough might require o many years for weathering to cause m Undisturbed Vashon Till has been the outer soils to loosen and soften f tested to be capable of supporting enough to slide off the slope, but loads in excess of 20,000 psf with no uncontrolled surface runoff can e m compressibility. increase that rate. The sloughing soils 0 p o will pile up at the base of the slope at Undisturbed Vashon Till is very stable an approximate . angle of 35 to 45 Q on slopes, and can stand vertically for degrees until the slope is completely 'z great heights. The outer surface on covered. The undisturbed soils are slopes. steeper than 45 degrees will. then protected from further p p rn� slowly erode from weathering and will. weathering. _ rnrn vN DESCRIPTION of WEATHERING c CO) 0 deeper. strong soils on steepAlthough glacially compacted soils the r are very strong and can stand at slopes, usually from trees breaking up steep slopes, the exposed surface of the strong soils by forcing their roots a those soils eventually becomes into relief cracks, or creating new ' Z t loosened and/or softened by the cracks. The tree roots also break up z weathering. processes. The the soils as the upper trees wave in o weathering processes include wetting the wind. Sometimes when the deeper rn and drying, freezing and thawing, root soils are too strong, the trees will action, direct rainfall,groundwater spread wide very shallow root seepage, land erosion from systems. The roots will hold the upper uncontrolled or concentrated surface weathered soils together, but if the r, stormwater runoff. soils become too saturated the soils ' and the trees will slide off slopes on Root action is the most damaging to the deeper strong soils. 11.3 RMIN rIFF E4112, h 111 • G 26 Jul 1998 page 4 of 6 pages PROJECT NUMBER 2336 Y Also when shallow rooted trees blow soils, therefore stability studies are ro riate. The stability over they carry the upper weathered usuaiiy not app p z soils with them. Trees are like of a slope depends on the extent of o s and destructive to weathering, the type of vegetation, n battering ram m downslope buildings. surface and groundwater conditions, and the natural angle of repose of the Uncontrolled stormwater runoff is the weathered soils under the normally c o most damaging to soils on steep occurring conditions. Slopes that have 0 slopes. Great damage can occur in a been. stable for years can become o short period of time as the result of unstable as the result of unusual =m p 10 fast moving water eroding the surface weather or seismic conditions; and a z f 9 and creating gullies. Stormwater that often from conditions created by man. infiltrates the more per Therefore the stability of a natural o Wn I weathered soils can break the slope is determined by the upper mrn capillary bond between the soil grains weathered soils rather than the o N that "glues" the grains together, and deeper unweathered soils. Because rn co can also increase the weight of the of the many variable parameters that rn v, upper weathered soils. The loosened effect the weathered soils, stability and softened heavier soils then slide studies in glacially compacted soils X are more experience or flow off the slope on top of the based on ex p z stronger unweathered soils: appropriate than. mathematical f studies. co z The soils that slide off the slope then o pile up at the toe and build back up Erosion due to groundwater seepage m the slope at the natural angle of is usually a slow process that occurs repose until they cover the slope and on top of the more impervious soil protect the underlying strong soils layers. The seepage will erode the from further weathering. from surface grain by grain. The seepage erosion is a slow but Deep seated slides do not normally continuous process, and therefore , '+occur in strong glacially compacted relentless. 1 31H EMAJI J P? HE 1.1 . .I )- r . ; . �,�. • . .. . .. . . . . . �� . . . „ . LI ,,'t 3 ' . : . FIGUI� E 3 SECTION of EXISTING and POTEi�TIAL SLOPE ... .::. . . i "Ital:. °Q ...... { a :%t�� . . °..N 0 . p ; ... � . �...:..... \P .. • `,� :: ... :. .: >'c a�� .. : ' :. :.. ...w°..: : SCALE 1 SQUARE.- • . , . .. .... ,_ ,., .. .. . :. ... . . .., .. { :::,/: • •.•; If { .. . .... S, .. .•. ' • .. 1 y • • ./. 1 I _ . . , { . I , • . i •�. . . i i / , . ... . 64.04,409, / { , . • i . , `• . . . . :- i. . • . ..t . • . • • i { I .' _ iii /! .'i _ i. 1 . t ....... ... ... d- 9.I ••......•....f....j.. .... . • . { _ a' ... i. . .. . . ... • {,'41 i i . • y I . . • : RAILROAD .... i i PUGET ....... TRACKS • : �` •''i € • ` .. • _ .. { • . SOUND 4 _Z ILL { { , ' i i { {.. { I...-._..,. . . < _ - I ..'..a':. `, I ..0 r i AS�a•li H�6P • lwp << v ,:i l 1 I ,1• , •'» ti / I . {•�• 1 ' . . .. f ;I'. . .l ` . . .i:.. . - .. - i _ . . I . - i. r . I y . .. `� -} ( . . ,1 t, --�. PROJECT NUMBER 2336 26 July 1998 P 1 a e 5 of 6 pages z Slides usually occur during or after a Concentrated surface runoff often ` heavy rainfall when the excess water erodes the weakened weathered a has increased the weight and soils, causing flow slides that can be z softened the already loosened the most damaging to downhill m weathered soils. The. excess water properties because of the velocities includes uncontrolled and/or achieved, and the distances that flow concentrated surface runoff from the slides can cover. m Ma properties above.* the slope. 0 2rn A j DISCUSSION and CONCLUSIONS D z Figure. 2 on the previous page shows ° �' of elevation of the sloe If the worst natural conditions (100 E s the contours p �. for the property north of Parcel A: The year rainfall, VII intensity earthquake) o N south property line for that property is occur in the lifetime of the houses (50 c also the north property line of Parcel years), then a maximum of 30 feet of t m N n A, therefore the contours of elevation slope might be lost. If the future r are .similar. Figure 2 owners become uncomfortable with for Parcel A r g _ shows the location of a section on the the slope conditions, they can protect D north property that would be similar against further weathering and :> z �. for Parcel A, and would be erosion by several methods; or z re resentative of the slopes of possible new methods in the future. o . p i, Parcels A and Be Feasible present day methods of M _ 4 underpinning foundations are also ,. t Figure 3 shows the section of the available. One method of slope . is . 55°. protection presently available Is slope. The average slope HEMPHIL.L anticipates that the final shotcrete with anchors. The slope resulting from the worst underpinning; the shotcrete, and the I.. conditions that could occur; including anchors can all be installed with I ortable a ui menta { uncontrolled runoff caused by man, p q p would be a roximatel w pp 45°. 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(reference point elevation) + �(urements from 6) Conclusion: 2� (actual) is greater eW an (allowed); therefore the house�S(� l V E D �r E DC 16.20.30 requirements �• f el t re ulreme�pe eLsn ver the b gh . q MAY 0 9 2005 L;\�LqL,DINO\M1SG'\Height CalculadonGrading Verification Worksheet doc DEVELOPMENT SERVICES C1 R CITY OF EDMONDS