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Home My WebLink AboutRS_Geotechnical_Report_170817_v1G'I Geotechnical Engineers, Geologists, & roup Nofthwest, Me. Environmental Scientists Mr. Bill Moorman CAM, LLC bill@billsmpteam.com Subject: GEOTECHNICAL ENGINEERING REPORT & INFILTRATION EVALUATION PROPOSED SHORT PLAT 2004 SHATTUCK AVE S RENTON, WASHINGTON Dear Mr. Moon-nan: 30M GEO Group Northwest, Inc. is pleased to submit this geotechnical report/infiltration evaluation for the proposed development at the subject site. The following report presents information from our review of the geologic map for the area, our subsurface investigation, our observations and our conclusions and recommendations pertaining to the proposed short plat. The subject site is a developed residential parcel located at 2004 Shattuck Ave S in Renton, Washington, as shown on the attached Plate I - Vicinity Map. There is an existing I -story home at the subject site as shown on the attached Plate 2 - Site Plan. The lot has an approximate area of 0.52 acres and has a roughly triangular shape as shown on the Plate 2 - Site Plan. The site has a gentle to moderate inclination slope which faces roughly west - northwest. Average slope inclination is around 10 percent from the horizontal with a maximum estimated inclination of 16 -percent. Based upon information provided by the project owner we understand that the proposed development will consist of subdividing the property into three residential building lots with a 20 -foot wide access tract at the north property line. The proposed subdivision is shown on the 13705 Bel -Red Rd - Bellevue, WA 98005 Phone: 425-649-8757 - Fax- 425-649-8758 May 23, 2017 G-4316 2004 Shattuck Ave S, Renton, Washington Page 2 attached Plate 3 - Proposed Lot Layout. We understand that future lot development will be for wood -framed single family residences. No details have been provided regarding the location of the homes or their floor elevations. We anticipate that the new homes will be sited roughly near the center of each of the new lots and that a paved access road will be constructed at the north access tract. GEOLOGIC CONDITIONS The USES geologic map for the site vicinity indicates that the soils at the subject lot consist of Quaternary -age Ground Moraine deposits (Qgt). These soils consist generally of ablation till C, Z:� over lodgement till. Till soils are generally described as a mixture of silt, sand and gravel which was deposited and overridden by glacial ice at least 14,000 years ago. The site is located near the mapped unit boundary for the Renton Formation (bedrock). This unit consists of sandstone, mudstone and shale. This formation also reportedly contains coal. On May 4, 2017 GEO Group Northwest excavated four exploratory test pits at locations at the subject site approximately located as shown on the attached Plate 2 - Site Plan. The test pits were excavated to depths between 5 and 7 feet below ground surface (bgs). Soils encountered at the test pits consist of loose to medium dense sandy and clayey SILT and fine sandy SILT (topsoil) overlying loose to very dense sandy SILT and sandy SILT with varying I tl amounts of gravel at a depth of 8 -inches to 1 -foot below ground surface (bgs). The underlying I competent medium dense to very dense soils were observed below depths of I to 2 -foot bgs. At test pits TP -1, TP -2 and TP -4 cemented soils were observed below depths of 4 to 4.5 -feet. Near the base of the TP -1 test pit some weathered shale rock was observed suggesting that the soils observed at the site consist of the weathered portion of the Renton Formation (bedrock). No groundwater seepage was encountered at the test pit locations from the ground surface to the bottom of the test pits. Mottling was observed at all of the test pits around the 1.5 to 3 -foot depth suggesting that possibly at some periods of the year perched seepage conditions develop on top of the underlying dense soils. The results of our subsurface investigation are shown on the attached Appendix A - Test Pit Logs and USCS Soil Legend. INFILTRATION EVALUATION Based upon our subsurface investigation the site soils consist of SILT soils which have relatively GEC) Group Northwest, Inc. May 23, 2017 G-4316 2004 Shattuck Ave S, Renton, Washington Page 3 low permeability. Additionally groundwater seepage was encountered at relatively shallow depth at all of the exploratory test pits. Natural infiltration for site stormwater is limited and likely causes a perched seepage zone to develop during some periods of the year. GEC Group Northwest, Inc., does not recommend siting infiltration facilities at the site due to the relatively low permeability of the site soils and the underlying dense to very dense condition which further restricts the infiltration. SEISMIC DESIGN CRITERIA Based upon our subsurface investigation the project site has Site Class C soil (Very Dense Soil and Soft Rock) per the IBC based upon the observed subsurface soil conditions. We have used the online USGS Seismic Hazard Design Map Tool to determine the following recommended seismic acceleration parameters based upon probablistic and deterministic ground -motions: S, = 1.3138 S, = 0.494g General Based upon the results of our study, it is our professional opinion that the site is geotechnically suitable for the proposed development. The future new homes may be constructed on standard shallow spread footing foundations bearing on top of the competent medium dense to very dense site soils. Site Preparation and General Earthwork The building pad areas should be (grubbed) stripped and cleared of surface vegetation and organic soils (topsoil). Z:� Silt fences should be installed around areas disturbed by construction activity to prevent sediment -laden surface runoff from being discharged off-site. Exposed soils that are subject to erosion should be compacted and covered with plastic sheeting. Under no circumstances should temporary excavation slopes be greater than the limits specified In GEC; Group Northwest, Inc. May 23, 2017 G-4316 2004 Shattuck Ave S, Renton, Washin.-ton Page 4 in local, state and national government safety regulations. Temporary cuts greater than four feet in height should be sloped at an inclination no steeper than I H: IV (Horizontal: Vertical) in the overlying loose site soils. If seepage is encountered at the excavation slopes should have inclinations of no steeper than 2H: IV for the temporary construction time period. If excavations with the aforementioned slope inclinations encroach upon the adjacent properties than shoring may be required. At the time of report preparation the final building locations as well as floor elevations were not available so the need for shoring could not be evaluated. Structural Fill All fill material used to achieve design site elevations below the building -areas and below non - structurally supported slabs, parking lots, sidewalks, driveways, and patios, should meet the requirements for structural fill. During wet weather conditions, material to be used as structural fill should have the following specifications: 1. Be free draining, granular material containing no more than five (5) percent fines (silt and clay -size particles passing the No. 200 mesh sieve); 2. Be free of organic material and other deleterious substances, such as construction debris and9 arbage; 3. Have a maximum size of three (3) inches in diameter. All fill material should be placed at or near the optimum moisture content. The optimum moisture content is the water content in soil that enables the soil to be compacted to the highest dry density for a given compaction effort. Based upon our subsurface investigation the site soils consist of sandy SILT. These soils are highly moisture sensitive and not recommended for use as structural fill, especially during wet weather conditions. If structural fills are required then we recommend that a granular fill material meeting the specifications noted above be imported to the site and that it be placed and compacted as described below. Structural fill should be placed in thin horizontal lifts not exceeding ten inches in loose thickness. Structural fill under building areas (including foundation and slab areas), should be compacted to Z__ at least 95 percent of the maximum dry density, as determined by ASTM Test Designation D- 1557-91 (Modified Proctor). GEC) Group Northwest, Inc. May 23, 2017 G-4316 2004 Shattuck Ave S, Renton, Washington Page 5 Structural fill under driveways, parking lots and sidewalks should be compacted to at least 90 percent maximum dry density, as determined by ASTM Test Designation D-1557-91 (Modified Proctor). Fill placed within 12 -inches of finish grade should meet the 95% requirement. We recommend that GEC} Group Northwest, Inc., be retained to evaluate the suitability of structural fill material and to monitor the compaction work during construction for quality assurance of the earthwork. I if M f I WIM VTO a Based upon our subsurface investigation the competent medium dense to very dense site soils were observed at depths ranging from I to 2 -feet below ground surface. The proposed building foundations and slabs should be constructed on top of these soils or on top of compacted structural fill placed on top of these soils. Building foundations should not be constructed on top of the overlying loose soils due to the risk of settlement related damage. Accordingly, we recommend that following the grubbing (removal of vegetation and topsoil) for the building pads then the overlying loose soils should be removed and where the excavation extends below the proposed foundation subgrades these areas should be backfilled with compacted structural fills. The site soils are relatively silty and therefore may become softened or may become yielding if subjected to construction traffic and wet weather. Additionally, dependent upon the time of year in which work occurs, perched groundwater seepage may flow into the building pad excavations and this water may negatively impact building pad subgrades. If work occurs during the wet weather we recommend that the building pad areas or footing areas be over -excavated to a minimum depth of 6 -inches below the proposed bottom of footing elevations and that crushed rock be placed to protect the subgrade. For building areas with slab -on -grade floors and where construction traffic will occur we recommend that the entire building pad be excavated and over - a geotextile filter fabric such as Mirafi 50OX and a minimum 6 -inch thickness of clean crushed rock be placed directly on top of the underlying medium dense to very dense competent soils (bearing soils). The underlying bearing soils should be approved by the geotechnical engineer at the time of construction prior to placement of the filter fabric and crushed rock. The bottom of the building pad excavation should be slightly sloped such that any water build-up on the pad may drain to an area where water may be removed from the building pad. For building areas without slab -on -grade floors then we recommend excavating trenches at footing areas such that the trench widths are equal to or greater than the footing width plus 2 -feet horizontal for each 1 - foot below grade. Following this trench excavation at the footing areas then the crushed rock may be placed within the trench to mitigate the risk of damage to foundation subgrades. The crushed rock thickness may be increased and serve as structural fill if over -excavation is GEC Group Northwest, Inc. May 23, 2017 G-4316 2004 Shattuck Ave S, Renton, WashinEton Pae 6 required. Poorly graded clean crushed rock do not require mechanical compaction provided that these materials are tracked and tamped in place. Spread Footing Foundations The proposed residential buildings can be supported on conventional spread footings bearing on top of the native in-situ medium dense to very dense site soils (competent soils) or on top of compacted structural fill placed on top of the competent site soils. Individual spread footings may be used for supporting columns and strip footings for bearing walls. Our recommended minimum design criteria for foundations bearing on the competent medium dense to very dense native soils or on compacted structural fill placed on top of the competent soils are as follows: - Allowable bearing pressure, including all dead and live loads Competent medium dense to very dense native in-situ soils = 2,000 psf Compacted structural fill on top of the competent soils = 2,000 psf - Minimum depth to bottom of perimeter footing below adjacent final exterior grade = 18 inches - Minimum depth to bottom of interior footings below top of floor slab = 18 inches - Minimum width of wall footings = 16 inches - Minimum lateral dimension of column footings = 24 inches - Estimated post -construction settlement = 1/4 inch - Estimated post -construction differential settlement; across building width = 1/4 inch A one-third increase in the above allowable bearing pressures can be used when considering short-term transitory wind or seismic loads. Lateral loads can also be resisted by friction between the foundation and the supporting compacted fill subgrade or by passive earth pressure acting on the buried portions of the foundations. For the latter, the foundations must be poured "neat" against the existing undisturbed soil or be backfilled with a compacted fill meeting the requirements for structural GEC} Group Northwest, Inc. May 23, 2017 G-4316 2004 Shattuck Ave S, Renton, WashinEton Paiie 7 fill. Our recommended parameters are as follows: - Passive Pressure (Lateral Resistance) 0 350 pcf equivalent fluid weight for compacted structural fill - 350 pcf equivalent fluid weight for native dense soil. - Coefficient of Friction (Friction Factor) • 0.35 for compacted structural fill • 0.35 for native dense soil We recommend that footing drains be placed around all perimeter footings. More specific details of perimeter foundation drains are provided below in the section titled: Subsurface Drainage. Slab -on -Grade Concrete Floors Slab -on -grade concrete floors may be constructed directly on top of the competent medium dense to very dense in-situ site soils or on top of compacted structural fills placed on top of the competent site soils. Slab -on -grade floors should not be constructed on top of the overlying loose soils or on top of wet yielding soils. If structural fills are to be placed at these areas then they should be compacted in accordance with the specifications in the section titled: Structural Fill. We recommend that we are retained to view the prepared slab subgrades and observe a proof -roll with a heavy piece of construction equipment to verify non -yielding condition prior to placement of the capillary break or concrete slabs. Toavoid moisture build-up on the subgrade, slab -on -grade concrete floors should be placed on a capillary break, which is in turn placed on the prepared subgrade. The capillary break should consist of a minimum of a six (6) inch thick layer of free -draining crushed rock or gravel containing no more than five (5) percent finer than the No. 4 sieve. A vapor barrier, such as a 10 -mil plastic membrane, is recommended to be placed over the capillary break beneath the slab to reduce water vapor transmission through the slab. Two to four inches of sand may be placed over the barrier membrane for protection during construction. Subsurface Drainage We recommend that subsurface drains, footing drains, be installed around the perimeter of the foundation footings. The drains should consist of a four (4) inch minimum diameter perforated rigid drain pipe laid at or near the bottom of the footing with a gradient sufficient to generate flow. The drain line should be bedded on, surrounded by, and covered with a free -draining rock, GEO Group Northwest, Inc. May 23, 2017 G-4316 2004 Shattuck Ave S, Renton, Washinton Pae 8 washed gravel, or other free -draining granular material. The drain rock and drain line should be completely surrounded by a geotextile filter fabric, Mirafi 140N or equivalent. Once the drains are installed, the excavation should be backfilled with a compacted fill material. The footing drains should be fightlined to discharge to the stormwater collection system. Z!, Under no circumstances should roof downspout drain lines be connected to the footing drainage system. All roof downspouts must be separately fightlined to discharge into the storm water collection system. We recommend that sufficient cleanouts be installed at strategic locations to allow for periodic maintenance of the footing drains and downspout tightline systems. Ll,N,HTATIONS This report has been prepared for the specific application to this site for the exclusive use of CAM, LLC and their authorized representatives. Any use of this report by other parties is solely at that party's own risk. We recommend that this report be included in its entirety in the project contract documents for reference during construction. Our findings and recommendations stated herein are based on field observations, our experience and judgement. The recommendations are our professional opinion derived in a manner consistent with the level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area and within the budget constraint. No warranty is expressed or implied. In the event that soil conditions not anticipated in this report are encountered during site development, GLC} Group Northwest, Inc., should be notified and the above recommendations should be re-evaluated. If you have any questions, or if we may be of further service, please do not hesitate to contact us. Sincerely, GEC) GROUP NORTHWEST, INC. Adam Gaston Project Engineer X -i 4 William Chang, P.E. Principal CLEC) Group Northwest, Inc. May 23, 2017 G-4316 2004 Shattuck Ave S, Renton, Washington Page 9 Attachments: Plate I -Vicinity Map Plate 2 -Site Plan Plate 3 - Proposed Lot Layout Appendix A -USCS Soil Legend and Test Pit Logs cc: Mr. Craig Krueger - cjkrueger@live.com G Group Northwest, Inc. --- VICINITY MAP Group Northwest Inc. 2004 SHATTUCK AVE S 13 N-22stm�7t0'>'WA4MRENTON, WASHINGTON � Ph— 425/649-875'7 FAX 4231649-8758 Rm.;t iufoQBeo�ouprn'.com SCALE: NTS DATE: 5-5-17 MADE: AG JOB NO.: G-4362 PLATE: 1 Jw*mays C) r Sa uas V t9a P€ may, p,.k yr Gem 5 t 5YY 1t S I Sth St ° at Tt iG- Parking Lot{,3 � ;i S t h St J Providence ? n S i 9th St PROJECT Si { g� Montclair r Apert S2ts=St-; ��su scs SYS Z3r4 8t � i►rarnas rnasriar % Pnr, , --- VICINITY MAP Group Northwest Inc. 2004 SHATTUCK AVE S 13 N-22stm�7t0'>'WA4MRENTON, WASHINGTON � Ph— 425/649-875'7 FAX 4231649-8758 Rm.;t iufoQBeo�ouprn'.com SCALE: NTS DATE: 5-5-17 MADE: AG JOB NO.: G-4362 PLATE: 1 WALL IS ,.O'Sw OF LINE -CONCRETE BLOCK WALL TPN 7222000370 w. END 6' WOOD FENCE kCsp S IS 0.6WE OF UNE 6' �FENCE IS LINEp�RC0�4C B s —E—END WALL IS - i + O.S'Sw OF LINE B� +r 4 -SW CORNER 6.5' WOOD FENCE IS ab'SW OF LINE W. END WIRE FENCE 14.5' r IS 1.2'SW OF LINE + r S�COF11'ER OF 4 -6.5' WOOD FENCE fI WOW DECK W S JVrsw W OF1E Fa 03 1 tPN 72210075 � sr Lr6t F I I I I - CONCRETE STEPS MAW Wr In -156 T 57 , i y` 1 CROSSES LINE X _ • ` ` WOW FENCE PUAL ! + ,;� _ 1I FOR (..,, ` ' 3 L6is ! f 33.r" OF Fa*CE 4S ►►ir+� _ 1 y eT�r NIERSEC110N 7 *OW L ANDMIS _ {gyp[ PAI%WR ' / k' R6>E 1 yrpOD STAM Pfd I 1 �� _} C>tiDER BLOO( 2 i + `� • . - �'. �, to Lad f J ' I y 0i0 6 4.1'SW OF LJIECE Is 1 WOE FEIw 40 79 ., ` f ; 1 1 1 1 S w LIF ua1E / TPN 7222000161 T 11000 FENCE 1 -FOUR} 1/2' REBAR AND CAP 'BNL LS 11332' 1 Q4 sDUTH1fST OF L� -SW FENCE CORNER I: IS t.tia'sW OF LUNE N -FOUND 1/Y REBAR AND z f % + CAP 'BHI LS 11332' 4153 i 5. Aon ay� nwCF_; iTERSICTiaM OA 0.1' 90UTFi1�5T OF LINE WX 1� Is. ;14.27 f r , yep I Grp 61E OF L714E r 5E CSR + ` / ' 4yA iri 11 w �'XI'Ar l 4 CS 0. OF LME TPN 7 2 210 0 01 89 i J • 1 I��\ � .4' r.n� tt I RAST ENO OF 6' W. > 6' +rn00 ! WOOD FENCE Ot \ 1 cS a -WS OF i 1' A/1 Is a stiF R I r. i1Q TS if-s'sW i a ` -FOUND t/2' REBAR No CAP ti.,. yy+lE • r 1 / OF LjNC �. ! �• f CAP ILS iQ:,_TP-1 , 0.4'N.�A.4'E. OF CRIER r _jMID .i- FENCE IS 1.1 `NE OF C"IE I r 20.00' _;• l \ ( / �" I ( ( TERSE � + 6 w000 FENCE Is - \ 1 II - IS (11�M OF UNEP NE FENCE CORNER- &3 ORNER - f 1 1 TPN 72220001 OXT. OF LINE FENCE WEST END OF 6 W+tlTE IN OISRFPAIR TO I- VINYL FENCE IS 0.4N. j IS 0 / S OF UNE TPN 7222000162 OF LINE FENCE s 32 ll + 4, CHAIN LINK FENCE 'lj UNE 33.3'E. OF i� 6 - CINDER BLOCK WALL a WHITE VINYL FENCE F04C E INTERSECTION ial.AT �. OF REQ� 5� Y`011 TPN 7222000164 Cj� 3 CO-OPERATWE COAL 6' 1MNfTE Vk1YL FENCE -FOUND PUNCH M ' BRASS G �MPa ACRE TRACTS DOME 1N 4'X4" CONCRETE r � VOLaFr°a'27 MONUMENT DOW 0.4' IN CASE 1.6'E. OF CE7NTERLINE. +78M A' M 154.73' 14 Firma BBASED UPON THE SURVEY BY AXIS -25-17. L- 1 Group Northwest, PROPOSED LOT LAYOUT , 2004 SHATTUCK AVE S is b� sour sr� smog �a we woos' RENTON, WASHINGTON rmazsieav-sass FAX azsrsas-ersa Evul mfo@gmwmp e.c SCALE: V=50' DATE: 5-517 1 MADE: AG JOB NO.: G-4362 PLATE: 3 APPENDIX A USUS SOIL LEGEND AND TEST PIT LOGS GEO Group Northwest, Inc. LEGEND OF SOIL CLASSIFICATION AND PENETRATION TEST � UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) - I MAJOR DIVISION CROUP TYPICAL DESCRIPTION LABORATORY CLASSIFICATION CRITERIA SYMBOL I I WELL GRADED GRAVELS, GRAVEL -SAND Cu = (D601 Of 0) greater than 4 GLEAN GRAVELS GW MIXTURE, LITTLE OR NO FINES Cc = (D302 )1(EH 0 D60) between 1 and 3 IDETERMINE PERCENTAGES OF -- `-- GRAVELS i (little or no POORLY GRADED GRAVELS AND GRAVEL -SAND GRAVEL AND SAND , (More Than Half i fines) GP NOT MEETING ABOVE REQUIREMENTS MIXTURES LITTLE OR NO FINES FROM GRAIN SIZE COARSE- Coarse Gains _.._ — - --------_-_------_- DISTRIBUTION —.-- --- GRAINED SOILS Larger Than No. 4 ! DIRTY GM { CURVE ATTERBERG LIMITS BELOW i SILTY GRAVELS, GRAVEL -SAND -SILT MIXTURES ' "A° LINE- Sieve) GRAVELS ( CONTENT or P.I. LESS THAN 4 -- OF FINES #--___GRAV EXCEEDS 121 ATTERBERG LIMITS ABOVE (with some ; fines) GC CLAYEY GRAVELS, GRAVEL -SAND -CLAY 3 MIXTURES COARSE GRAINED "A" LINE. SOILS ARE or P.I. MORE THAN 7 _ .- - - -------- ---- -- - -i CLASSIFIED AS SANDS SW WELL GRADED SANDS, GRAVELLY SANDS. LITTLE FOLLOWS: Cu = (D60/D10) greater than 6 CLEAN OR NO FINES Cc = (D362) i (DIO' D60) between 1 and 3 SANDS (More Than Half Mare Than HaI€ by Coarse Grains } (Iittie or SP POORLY GRADED SANDS GRAVELLY SANDS i _ 5% Fine Grained. NOT MEETING ABOVE REQUIREMENTS Weight Larger Smaller Than No 4' fines) LITTLE OR NO FINES # GW, GP, S, SP SW, Than No.20(i Sieve) - - ! ATTERBERG LIMITS BELOW ' > 12 Fine Grained: Sieve DIRTY SM ! SILTY SANDS, SAND -SILT MIXTURES j °A° LINE GM, GG, SM, SC I SANDS CONTENT OF I with P.J.LESS THAN 4 _-- FINES {Nth some ( s to 12% Fine EXCEEDS 12l ATTERBERG LIMITS ABOVE fines) SC ! CLAYEY SANDS, SAND -CLAY MIXTURES Grained: use dual j "A" LINE Symbols ( with P.I. MORE THAN 7 T - Liquid L.;mi# INORGANIC SILTS, ROCK FLOUR, SANDY SILTS SILTS 501 ML OF SLIGHT PLASTICITY 60 {Below A -Line on A-U^.e Plasticity Chart, 4PLASTICITY CHART ! 1 FENS -GRAINED Negligible Organic} ( Liquid Limit j i INQR,r$AF{#tC SILTS, MICACEOUS OR 50 FOR SOIL PASSING E SOILS > 50° MH DIATOMACEOUS, FINE SANDY OR SILTY SOIL. NO. 40 SIEVE _ ---- -� -- -2CH or OR !' 1 Limn INORGANIC CLAYS OF LOW PLASTICITY, 1 X 40 -+—+- -quid CLAYS CL GRAVELLY, SANDY, OR SILTY CLAYS, CLEAN � E D (Above A -Line on < 34l ( CLAYS i i f 3 ; Plac?icity Chart, i 30 -Negligible Organic); Liquid Limit# CH INORGANIC CLAYS OF HIGH PLASTICITY, FAT > 50%. j ( CLAYS ' CL or OL More Than Halt by ^- l 20 q Weight Smaller 1 Liquid Limit ORGANIC SILTS AND ORGANIC SILTY CLAYS OF £ MH or ',?H I i /�L' Than No, zJQ ORaAA-iiC SILTS ; 50% -^3i LOW PLASTICITY to i Sieve CLAYS i —'----- r r L M ML ! i (Below A -Line ors�a piacficty Chart) j Liquid Limitu OR ORGANIC CLAYS OF HIGH PLASTICITY R i > 50°• { 0 10 20 30 40 50 60 70 80 90 100 110 -------- -- -- LIQUID LIMIT I%) HIGHLY ORGANIC SOILS Pt PEAT AND OTHER HIGHLY ORGANIC SOILS t 1 SOIL PARTICLE SIZE GENERAL GUIDANCE OF SOIL ENGINEERING PROPERTIES FROM STANDARD PENETRATION TEST (SPT) U.S. STANDARD SIEVE FRACTION Passing Retained SANDY SOILS SILTY & CLAYEY SOILS SizeSieve Size Sieve i tnnl i { MM Blow Relative Friction Blow ! Unconfined ___-- -_} _ _-___-- _.___ __ Counts Density Angle DescdMion Counts Strength Descretion SILT 1 CLAY ' #2i30 0 -ills # a N ,� # ,, degree ( N qu, tsf SAND 0-4 0 -15 Very Loose 2 ; '0_25 Ve y soft FINE #40 0.425 #200 j 0.075 4-10 15 - 3526 - 30 Loose 2 - 4 0.25 - 0.50 Soft i MEDIUM #10 ! 2 1 t#40 0.425 # t0 - 30 i 35-65 # 26.35 Medium Dense 4-8 0.50 - I,00 Medium Stiff COARSE 1 � #4 _ 4 75 #10 ( ------------ --— 2 �— 30-50 65-85 ; 35-42 Dense B-15 1.00 - 2.00 # Stiff G�y 50 85-100 3B-46 Ve y Dense 15-30 ; 2-00-4,00 Very Stiff FINE 19 44 4.75 i i i > 30 > 4.€30 Hard COARSE76 I 19 COBBLES 76 mm to 203 mm --------- -- �r - Group Northwest, Inc. BOULDERS > 20.3 mm vrrrr' - _ Geotechnical Engineers, Geologists, & ROCK i Environmental Scientists FRAGMENTS > 76 mm 13240 NE 20th Street, Suits 10 Bellevue. WA 98005 ROCK > >0.76 cubic meter in volume Ph e (425) 6t+3-8757 Fax {425} 649-$i58 PLATEAl 19*1 IF9111 LOGGED BY AG TEST PIT DATE: 05/04/2017 DEPTHII USES SOIL DESCRIPTION SAMPLE Water No. % OTHER TESTS/ COMMENTS OTHER TESTS/ ft. ML Dark brown fine sandy and clayey SILT with occasional gravel, moist, SOIL DESCRIPTION Probe 10-12" % COMMENTS - - - - -Loose (tqaso -il I ---------------------------------------- ML Probe 4-5" NIL Tan and mottled fine sandy SILT with occasional cobbles and gravel, Probe 1-2" wet to moist, medium dense to vers, dense NIL Tan and mottled fine sandy SILT with some gravel, wet to moist, Probe 1 -2" Probe <I dense ' to very dense Cemented soil below 4' bgs, weathered shale observed 5 Probe <1" Total depth of test pit = 5 ft Ings (below ground surface) Cemented soil below 4' bgs 5 Perched groundwater seepage between 16 to 36 -inches bgs Probe <1/2" Dense soils encountered below 20 -inches bgs 10 15 Perched groundwater seepage between 24 and 40 -inches Ings IM -1 LOGGED BY AG TEST PIT DATE: 05/04/2017 DEPTH SAMPLE Water OTHER TESTS/ ft. UCS SOIL DESCRIPTION No. % COMMENTS ML Dark brown fine sandy and clayey SILT, moist, loose Probe 6-10" Probe 2-4" NIL Tan and mottled fine sandy SILT with some gravel, wet to moist, Probe 1 -2" dense ' to very dense Probe <1" Cemented soil below 4' bgs 5 Probe <1/2" Total depth of test pit = Tbgs (below ground surface) Perched groundwater seepage between 24 and 40 -inches Ings 10 Dense soils encountered below l' bgs 15 Group Northwest, Inc. Geotechnical Engineers, Geologists, & Environrris-rital Scientists TEST PIT LOGS PROPOSED SHORT PLAT 2004 SHATTUCK AVE S RENTON, WASHINGTON 7OGGED BY AG TEST PIT DATE: 05/04/2017 --- -- ------ ---------- - ------- -------- DEPTH ft. USCS SOIL DESCRIPTION SAMPLE No. Water % OTHER TESTS/ COMMENTS USCS NIL --------------------------------------------------------- Dark brown fine sandy SILT, moist, loose (topsoil) topsoil) COMMENTS Probe 6-10" ML Dark brown fine sandy SILT, moist, medium dense NIL Tan and mottled fine sandy and clayey SILT becoming sandy SILT Probe 2-4" Probe 8-12" (est 40% sand), wet to moist, dense to very dense NIL Tan, orangish and mottled fine sandy SILT with occasional gravel, wet Probe 2" to moist, loose to very dense Probe <I 5 5 Cemented soil below 4.5` bgs Total depth of test pit = 6.5' bgs (below ground surface) Total depth of test pit = 6 -ft bgs (below ground surface) Perched groundwater seepage between 24 and 60 -inches bgs Perched groundwater seepage between 24 to 28 -inches bgs Dense soils encountered below 2` bgs Dense soils encountered below I -ft bgs 10 10 15 15 LOGGED BY — AG TEST PIT DATE: 05/04/121,017 DEPTH SAMPLE Water OTHER TESTS/ ft. USCS SOIL DESCRIPTION No. % COMMENTS ML Dark brown fine sandy SILT, moist, medium dense Probe 4-6" Probe 8-12" NIL Tan, orangish and mottled fine sandy SILT with occasional gravel, wet Probe 2" to moist, loose to very dense 5 Cemented soil below 4.5` bgs Total depth of test pit = 6.5' bgs (below ground surface) Perched groundwater seepage between 24 and 60 -inches bgs Dense soils encountered below 2` bgs 10 15 UEO 1111111INMIMME111 Geotechnical Engineers, Geologists, & Environmentai Scienbsts TEST PIT LOGS PROPOSED SHORT PLAT 2004 SHATTUCK AVE S RENTON, WASMNGTON