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Geotechnical Evaluation.pdfJuly 19, 2017 ES-5323 RECE#VEr APR 1 c 2018 Ms. Kari Johannessen 10727 — 226" Street Southwest Edmonds, Washington 98002 Subject: Geotechnical Evaluation Johannessen Short Plat 10727 — 2261h Street Southwest Edmonds, Washington Reference: Lovell-Sauerland & Associates, Inc. Preliminary Development Plan, dated April 21, 2008 Earth Solutions NW,ic Earth Solutions NW I-I_c • Geotechnical Engineering • Construction Monitoring • Environmental Sciences Department of Ecology (DOE) 2012 Stormwater Management Manual for Western Washington (SMMWM) Amended December 2014 United States Department of Agriculture Natural Resources Conservation Service Online Web Soil Survey (WSS) resource James P. Minard Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangles Washington, 1983 Dear Ms. Johannessen: As requested, Earth Solutions NW, LLC (ESNW) has prepared this infiltration and geotechnical evaluation letter for the proposed development. Project Description The subject site located at 10727 — 226th Street Southwest in Edmonds, Washington, as illustrated on the Vicinity Map (Plate 1). The site consists of one residential tax parcel (Snohomish County parcel number 27032500310300) totaling approximately 2.35 acres of land area. The property is currently developed with a single-family residence and associated improvements located in the northwestern portion of the site; the remainder of the site consists primarily of yard areas and lightly forested land. -1805 - "136th Place N.E., Suite 201 - Bellevue, WA 9ti005 0 (425) 449-4704 - FAX (425) 449-4711 Ms. Kari Johannessen ES-5323 July 19, 2017 Page 2 Within the site, there is a knoll occupying the northwestern half of the site (existing residence). The ground drops off at about 8 to 38 percent grade to a low-lying, nearly level portion of the site. The subject site is bordered to the north, east, and west by residential structures and to the south by 226'h Street Southwest. Based on the site development plan provided to us, the existing single-family residential structure will remain and two new single-family residential structures will be constructed within the southern portion of the site. We anticipate grading activities will include cuts and fills to establish the planned building alignment. Based on the existing grades, we estimate cuts to establish building pad and foundation subgrade elevations will be on the order of five feet or less. However, grading plans were not available at the time this letter was prepared. Drywells will be incorporated into site designs as a means of stormwater management for new impervious surfaces. Site improvements will also include underground utility installations. At the time this letter was prepared, specific building load values were not available. However, we anticipate the proposed residential structure will consist of relatively lightly loaded wood framing supported on conventional foundations. Based on our experience with similar developments, we estimate wall loads on the order of one to two kips per lineal foot and slab - on -grade loading of 150 pounds per square foot (psf . If the above design assumptions are incorrect or change, ESNW should be contacted to review the recommendations in this evaluation. ESNW should review the final design to verify the geotechnical recommendations provided in this letter have been incorporated into the plans. Subsurface Conditions As part of this geotechnical evaluation, An ESNW representative observed, logged, and sampled two test pits on June 29, 2017, excavated at accessible locations within the proposed development area. The approximate locations of the test pits are depicted on Plate 2 (Test Pit Location Plan). Please refer to the test pit logs provided in Appendix A for a more detailed description of subsurface conditions. Representative soil samples collected at the test pit locations were analyzed in general accordance with the Unified Soil Classification System (USCS) and United States Department of Agriculture (USDA) methods and procedures. Topsoil and Fill Topsoil was observed extending to depths of approximately 4 to 6 inches below existing grades. The topsoil was characterized by dark brown color and fine organic material. Significant fill deposits were not encountered at the test pit locations during our fieldwork. Fill may be present, however, within proximity to existing structural improvements. Where fill is encountered during construction, ESNW should be consulted to evaluate the suitability for reuse as structural fill. Earth Solutions NW, LLC Ms. Kari Johannessen July 19, 2017 Native Soil ES-5323 Page 3 Underlying the topsoil, soil conditions at the test pit locations were observed to consist of poorly graded gravel with sand and poorly graded sand (USCS: GP and SP, respectively) outwash deposits. The native soil deposits were generally observed to be in a medium dense condition beginning at depths of approximately one to three feet below existing grades. Geologic Setting The referenced geologic map indicates the project location is underlain by Vashon advance outwash (Qva). The advance outwash is characterized primarily as sand and gravel deposit. The soil conditions observed at the test pit locations are generally consistent with the geologic mapping. Groundwater Groundwater was not encountered at the test pit locations at the time of our exploration. Perched seepage, however, may be encountered during site grading activities, particularly during the winter, spring, and early summer months. It is noted that groundwater seepage rates and elevations fluctuate depending on many factors, including precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater flow rates are higher during the wetter, winter months. Based on subsurface conditions observed, we do not anticipate groundwater will impact the proposed infiltration facilities. Geotechnical Considerations Based on the results of our investigation, the proposed single-family structures can be supported on conventional spread and continuous footings bearing on undisturbed competent native soil, compacted native soil, or new structural fill. Based on the soil conditions encountered at the test sites, competent native soils suitable for support of foundations should be encountered beginning at depths of approximately one to three feet below existing grades. The soils encountered at the test pit locations generally have a low to moderate sensitivity to moisture based on the fines content of the soil. Compaction of the soil to the levels necessary for use as structural fill may be difficult during wet weather conditions. Where loose or unsuitable soil conditions are encountered at foundation subgrade elevations during site preparation activities, compaction of the soils to the specifications of structural fill, or overexcavation and replacement with granular structural fill will be necessary. Structural fill should consist of suitable granular soils compacted to 95 percent of Modified Proctor (ASTM D1557). Organic material exposed at foundation subgrade elevations must be removed and grades restored with structural fill. Earth Solutions NW, LLC Ms. Kari Johannessen ES-5323 July 19, 2017 Page 4 Provided the structures will be supported as described above, the following parameters can be used for design of the new foundations: • Allowable soil bearing capacity 2,500 psf Passive earth pressure 300 pcf (equivalent fluid) • Coefficient of friction 0.40 A one-third increase in the allowable soil bearing capacity can be assumed for short-term wind and seismic loading conditions. With structural loading as expected, total settlement in the range of one inch is anticipated, with differential settlement of about one-half inch. The majority of the settlements should occur during construction, as dead loads are applied. Seismic Considerations The 2015 IBC recognizes ASCE for seismic site class definitions. In accordance with Table 20.3-1 of ASCE, Minimum Design Loads for Buildings and Other Structures, Site Class D, should be used for design. In our opinion, the site is not susceptible to liquefaction. The native soil relative density and the absence of an established shallow groundwater table are the primary bases for this opinion. Drainage Surface grades must be designed to direct water away from the buildings. The grade adjacent to the buildings should be sloped away from the buildings at a gradient of at least 2 percent for a horizontal distance of at least four feet. In our opinion, perimeter footing drains should be installed at or below the invert of the building footings. ESNW can reevaluate the need for footing drains during construction, if requested. Infiltration Evaluation We understand stormwater will likely be managed by infiltration drywells located near the southern area of the subject site. The referenced 2014 Stormwater Management Manual for Western Washington (2014 SMMWW) was consulted, as required. As indicated in the Subsurface section of this letter, native soils encountered during our fieldwork were characterized primarily sand and gravel, outwash deposits. Based on the results of USDA textural analyses, the native soils were classified primarily as slightly to extremely gravelly sand with fines contents of about 0.1 to 0.9 percent (irrespective of gravel content). Earth Solutions NW, LLc Ms. Kari Johannessen ES-5323 July 19, 2017 Page 5 In -situ testing was completed in accordance with the Small-scale Pilot Infiltration Test (PIT) procedure, as outlined in Volume III, Chapter 3, Page 526 of the 2014 SMMWW. The testing was completed at depths of approximately four feet below existing grades at TP-1 and approximately four -and -one-half feet at TP-2. The testing was completed within the native sand and gravel outwash soils. The in -situ rate obtained during testing was 62 inches per hour at TP-1 and 55 inches per hour at TP- 2. Because the infiltration rate obtained from in -situ testing is considered to be a short-term rate, correction factors must be applied in order to determine a long-term design rate. The correction factors outlined below were used in accordance with Table III-3.3.1 of the 2014 SMMWW outlined in Volume III, Chapter 3, Page 529. The correction factors, along with the measured infiltration rate, were incorporated into the following equation: KSat design = Ksar initial x CFI x CFr x CFn,. • Measured (Ksat initial) 55 inches per hour Site variability CF„ = 0.75 Test method CFt = 0.5 Degree of influent control CFm = 0.9 • Long-term design infiltration rate (Ksat design) 18 inches per hour The design infiltration rate is applicable to facilities located in proximity to the infiltration test locations. Should revised locations be pursued, ESNW should be contacted to perform additional in -situ testing, as necessary. We recommend incorporating emergency overflow provisions in the facility designs. ESNW should be retained to observe the construction of infiltration facilities on the subject site in order to confirm soil conditions are as anticipated. Supplementary geotechnical recommendations may be provided at the time of construction, where necessary. Drywell Sizing Typical drywell sizing recommendations are based on the USDA classifications of the soils observed at the proposed bottom of facility. The referenced 2014 SMMWW provides sizing criteria for soils considered generally suitable for full infiltration (medium to coarse sands and gravels). Extremely gravelly sand was identified at the proposed bottom of facility locations. For sizing of roof runoff infiltration drywells, the site soils should be designed as course sands. In our opinion, the soils observed at the approximate bottom of facilities should be considered suitable for full infiltration applications. As stated in Volume II, Chapter 3, Page 454 of the DOE stormwater manual, drywells placed within coarse sands must have at least 360 cubic feet of gravel for every 1,000 square feet of tributary impervious surface. It is our opinion that an overflow should be incorporated into facility designs. Earth Solutions NW, LLC Ms. Kari Johannessen July 19, 2017 On -site Stormwater Management ES-5323 Page 6 Pursuant to City of Edmonds stormwater management requirements, implementation of on -site stormwater BMPs are required for proposed developments in accordance with specified thresholds, standards, and lists. The intent of BMP implementation is to infiltrate, disperse, and retain stormwater runoff on site to the extent feasible. We understand the proposed development intends to add over 5,000 square feet of new hard surface and therefore must comply with Minimum Requirements (MRs) 1 through 9, as outlined on Pages 42 through 70 of Volume I of the referenced stormwater manual. MR 5 concerns on -site stormwater management, and the viability of specific BMPs are to be evaluated for each type of proposed surface. The table below summarizes our evaluation of the required BMPs for MR 5, as outlined in the referenced stormwater manual, from a geotechnical standpoint. It is instructed in the referenced stormwater manual that BMPs are to be considered in the order listed (from top to bottom) for each surface type, and the first BMP that is determined to be viable should be used. For completeness, however, we have evaluated each listed BMP for the proposed surface types. KOMP .. ] Viable? I Limitations or Infeasibility Criteria T5.13: Post -construction soil quality and depth Yes (Volume V, Chapter 5) - T5.30: Full dispersion (Volume V, Chapter 5) T5.10A: Downspout full infiltration systems (Volume III, Chapter 3) T7.30: Bioretention (Volume V, Chapter 7) T5.14A: Rain Gardens (Volume V, Chapter 5) T5.10B: Downspout dispersion systems (Volume III, Chapter 3) T5.10C: Perforated stub -out connections (Volume III, Chapter 3) Other Hard Surfaces T5.30: Full dispersion (Volume V, Chapter 5) T5.15: Permeable pavement (Volume V, Chapter 5) T7.30: Bioretention (Volume V, Chapter 7) T5.14A: Rain Gardens (Volume V, Chapter 5) T5.12: Sheet flow dispersion T5.11: Concentrated flow dispersion (Volume V, Chapter 5) None. No slopes greater than 33 percent are present. No The proposed project will not preserve at least 65 percent of the site. Based on results of the PIT, a design Yes infiltration rate of 18 in/hr can be considered for design. Based on results of the PIT, a design Yes infiltration rate of 18 in/hr can be considered for design. Proper setbacks and vegetated flow paths No are not available. Yes I None. No The proposed project will not preserve at least 65 percent of the site. Based on results of the PIT, a design Yes infiltration rate of 18 in/hr can be considered for design. Based on results of the PIT, a design Yes infiltration rate of 18 in/hr can be __considered for design. Sheet flow dispersion and concentrated No flow dispersion may be feasible, however, proper setbacks and vegetated flow paths may not be available. Earth Solutions NW, LLC Ms. Kari Johannessen July 19, 2017 Utility Support and Trench Backfill ES-5323 Page 7 In our opinion, the native soils anticipated to be exposed in utility excavations should generally be considered suitable for support of utilities. Organic or highly compressible soils encountered in the trench excavations should not be used for supporting utilities. The native soils should generally be suitable for use as structural trench backfill. Moisture conditioning of the soils will likely be necessary prior to use as structural backfill. Utility trench backfill should be placed and compacted to 95 percent of the modified proctor, or to the presiding jurisdiction specifications. Limitations The recommendations and conclusions provided in this geotechnical evaluation letter are professional opinions consistent with the level of care and skill that is typical of other members in the profession currently practicing under similar conditions in this area. A warranty is not expressed or implied. Variations in the soil and groundwater conditions observed at the test pit locations may exist, and may not become evident until construction. ESNW should reevaluate the conclusions in this geotechnical evaluation letter if variations are encountered. Should you require additional information, or have questions, please call. Sincerely, EARTH SOLUTIONS NW, LLC Adam Z. Shier, G.I.T. Staff Geologist Attachments: Plate 1 - Vicinity Map Plate 2 - Test Pit Location Plan Test Pit Logs Grain Size Distribution cc: Leif Helleren Construction, Inc. Attention: Mr. Leif Helleren (Email only) Henry T. Wright, P.E. Senior Project Engineer Earth Solutions NK LLC S, 2 �llptr'�Y,' ria 1 Stl A?�l f it 4. �� ±r a n� rx x: '.:'N'f` ,hr' YIlk _ TN tlTlfl 1X �Ic • 1c naa P.wA tafll.r !� JAIN►" F711F- i "i Sr neml�`•.,vraslrf� fl c33 _ Gft� d r ��a 11�SI+is t ' sl 9N dots: lash tH , t 1zydC' 4•a1!v 1ttr_ a � -- Wf�_.I . �� „Uil 'l.At1'► !��A' fy 7.t�T Will �I 1 ?r A 36 I SJ ilsl� f,c?*H a 5 K��ta•. I.t 51, s G t�1 • . iy/ 1• =�:•, tos� ";' g '��nr��tn�%H �' st ➢II; 2 IL �� r� --,• >' �' , eit f3'sc��;E ,rt a C:10i_ t c: t ,M 1 = rifh�1 ��11 ti AIt Yr IT 'C 2urfr; � r ra � f nth R m - a+ Ill.i .flfi;j 1•Syt�. Q, 1111►.icc� Y tr.� Sjj~� OAL1- y i v ��tNkhf. tl(,fllk t!1 tL' /(.' ,H� C'G �@ 9A' t = v _ S- W Wss �� II��11 ^irk t^SN$ 9 $ � •'711i1 f./ ii.'•x' S(� M - - "`�'3fN�tl�7Tu413tf'fill �f ►r"+ 9 :w,IM iA , K1N NX1i 7h•iNwv w 3s fiStfl� 7 11 IT /Ijjff-k.r7.Y3f��. `Y,1Jh,1VItI r :rC }.Ir � n Sf 1��O171ZI tr JIVI ".!Xk.V_ t M±F_l7ltm I 3iN_ ;a � :r in R 411�_ 1 14 I[xe► Imu �Ir,r1� s.•i 11SIw�.j� � (iATtls tr rl� jag k PARX Iw r1SfRWIr •�If � Kt. /f',1�TYIt; sf' •M11' �hlrh 46j, '!4`+1� � E ��, •x+ltsr t*t�'!Ii , ••>ti tfFlfCh if/Mrll� 51 1I wdx �l W L uiliT �F' v li4ki,-� .1t141 31 � �fdb T.k r F = h Ike 1[gfM 1 f, %W 1; W rift •�� S. � is r _. � f31N S� � ST �• i t>�'.tt _-t)riib�st �Irelu �as;o.�,� 'K71f8ii—r: tu�orRaiL cho i of 0.u1f VI�t 'N If�1N K Z'4 I pt 1 n Q m LUr M=• 1st ,' �� •- e a _ � t F sctt_ jr.v ,r.wr. ,� :�,,' R' pC� , f k rJf i ` .�rf y g�I tr I IRA Q Reference: NORTH Snohomish County, Washington Map 474 r ., By The Thomas Guide Rand McNally Vicinity Map 32nd Edition Johannessen Short Plat Edmonds, Washington NOTE: This plate may contain areas of color. ESNW cannot be Drwn. MRS Date 07/19/2017 Proj. No. 5323 responsible for any subsequent misinterpretation of the information Checked AZS Date July 2017 Plate 1 resulting from black & white reproductions of this plate. 226 FI I ; rRGL7 C C ma o ark LEGEND o = N m Co TP 1 Approximate Location of 0 y — ■ — ESNW Test Pit, Proj. No. =. I ES-5323, June 2017 iE o w m E _ L - Subject Site 0 W Existing Building Proposed Building NORTH001 ""N2 ;4 0 30 60 120 Scale in Feet NOTE: The graphics shown on this plate are not intended for design purposes or precise scale measurements, but only to illustrate the approximate lest locations relative to the approximate locations of Drwn By MRS existing and / or proposed site features. The information illustrated is largely based on data provided by the client al the time of our study. ESNW cannot be responsible for subsequent design changes Checked By, or interpretation of the data by others. AZS NOTE: This plate may contain areas of color. ESNW cannot be Date responsible for any subsequent misinterpretation or the information 07/19/2017 resulting from black & white reproductions of this plate. Proj. No. 5323 Plate 2 Earth Solutions NWLLC SOIL CLASSIFICATION CHART MAJOR DIVISIONS SYMBOLS TYPICAL DESCRIPTIONS GRAPH LETTER GRAVEL AND CLEAN GRAVELS ',� �� .M�RES, ' a. GW WELL'GRADED GRAVELS, GRAVEL - LITTLE OR NO FINES GRAVELLY SOILS (LITTLE OR NO FINES) "3° , OOo p Q aQ C GP POORLY -GRADED GRAVELS, GRAVEL - SAND MIXTURES, LITTLE OR NO FINES COARSE GRAINED SOILS MORE THAN 50% OF COARSE GRAVELS WITH FINES o Q "° o ° D GM SILTY GRAVELS, GRAVEL - SAND - SILT MIXTURES FRACTION RETAINED ON NO. 4 SIEVE (APPRECIABLE AMOUNT OF FINES) GC CLAYEY GRAVELS, GRAVEL - SAND - CLAY MIXTURES MORE THAN 50°k OF MATERIAL IS SAND AND CLEAN SANDS Sw SANDS,LITTLE SANDSNO, GRAVELLY INES LARGERTHAN NO.200 SIEVE SIZE(LITTLE SANDY SOILS OR NO FINES) SP POORLY -GRADED SANDS, GRAVELLY SAND. LITTLE OR NO FINES SANDS WITH FINES SM SILTY SANDS, SAND - SILT MIXTURES MORE THAN 50% OF COARSE FRACTION PASSING ON NO. 4 SIEVE (APPRECIABLE AMOUNT OF FINES) S`. CLAYEY SANDS, SAND - CLAY MIXTURES INORGANIC SILTS AND VERY FINE ML SANDS. ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITH SLIGHT PLASTICITY FINE GRAINED SOILS SILTS LIQUID LIMIT AND LESS THAN 50 CLAYS CL INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEAN CLAYS _ _ OL ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY MORE THAN 50% OF MATERIAL IS SMALLER THAN NO, 200 SIEVE MH INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE SAND OR SILTY SOILS SIZE SILTS AND LIQUID LIMIT CLAYS GREATER THAN 50 CI I INORGANIC CLAYS OF HIGH PLASTICITY OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS HIGHLY ORGANIC SOILS .� 2„2 •� % PT PEAT, HUMUS, SWAMP SOILS WITH HIGH ORGANIC CONTENTS DUAL SYMBOLS are used to indicate borderline soil classifications. The discussion in the text of this report is necessary for a proper understanding of the nature of the material presented in the attached logs. Earth Solutions NW TEST PIT NUMBER TP-1 1805 -136th Place N.E., Suite 201 PAGE 1 OF 1 Bellevue, Washington 98005 Telephone: 425-449-4704 Fax: 425-449-4711 CLIENT Kari Johannessen PROJECT NAME Johannessen Short Plat PROJECT NUMBER ES-5323 PROJECT LOCATION Edmonds, Washington DATE STARTED 6/29/17 COMPLETED 6/29/17 GROUND ELEVATION _ TEST PIT SIZE EXCAVATION CONTRACTOR CLE GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION — LOGGED BY AZS CHECKED BY HTW AT END OF EXCAVATION — NOTES Depth of Topsoil & Sod 4": soil AFTER EXCAVATION -- w a. of U wIn TESTS O MATERIAL DESCRIPTION a z C9 0 pS _ 10.5 5 Dark brown, TOPSOIL Tan silty SAND with gravel, medium dense, moist MC = 6.60% SM MC = 3.20% — �`t 2.0 Gray poorly graded GRAVEL with sand, medium dense, damp �l �D MC = 3.00% Fines = 0.90% O C (USDA Classification: extremely gravelly SAND) 5 ° �o [� 0 GP ,O v D �Q ,U D o(," -becomes moist MC 11.70% Test Pit terminated at 9.0 feet below existing grade. No groundwater encountered during excavation. No caving observed. I I i Bottom of test pit at 9.0 feet. Earth Solutions NW TEST PIT NUMBER TP-2 1805 -136th Place N.E., Suite 201 PAGE 1 OF 1 Bellevue, Washington 98005 Telephone: 425-"9-4704 Fax: 425-449-4711 CLIENT Karl Johannessen PROJECT NAME Johannessen Short Plat PROJECT NUMBER ES-5323 PROJECT LOCATION Edmonds, Washington DATE STARTED 6/29/17 COMPLETED 6/29117 GROUND ELEVATION TEST PIT SIZE EXCAVATION CONTRACTOR CLE GROUND WATER LEVELS: EXCAVATION METHOD _._ ATTIME OF EXCAVATION -- LOGGED BY AZS CHECKED BY HTW AT END OF EXCAVATION --- NOTES Depth of Topsoil &Sod 6": grass AFTER EXCAVATION — w W U 1 L TESTS Q O MATERIAL DESCRIPTION ra 0 Q z ] (� n_ SQ = = 0_s Dark brown TOPSOIL, roots Brown silty SAND with gravel, medium dense, moist MC = 7.60% Sim MC = 2.80% 0 Gray poorly graded GRAVEL with sand, medium dense, damp e � _ v�0 e Qo MC = 2.30% Q 3 [USDA Classification: extremely gravelly SAND] 5 Fines = 0.20% GP a �p - oQD o& Q 7.0 _ Gray poorly graded SAND, medium dense, moist - SP MC = 16.60% 9.0 [USDA Classification: slightly gravelly SAND] Fines = 0.10% Test pit terminated at 9.0 feet below existing grade. No groundwater encountered during excavation. No caving observed. Bottom of test pit at 9.0 feet. Earth Solutions NW, LLC GRAIN SIZE DISTRIBUTION 1805 - 136th PL N.E., Suite 201 Bellevue, WA 98005 Telephone: 425-449-4704 Fax: 425-449-4711 CLIENT Kari Johannessen - PROJECT NAME Johannessen Short Plat PROJECT NUMBER ES-5323 PROJECT LOCATION Edmonds Washington U.S. SIEVE OPENING IN INCHES I U.S, SIEVE NUMBERS HYDROMETER 10 919 9 8 a 7 7 6 6 m 5 w 5 z LL z 4 w 4 w IL 3 3i 2 2 1 1 1UU iu I v., GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse fine 1coarse medium fine 01 i Specimen Identification Classification 1 Cc Cu f I l�nw. n_-..., C..a... el.. elrwnllw Smnrl I ICCS• (%P with Sand- 0.07 166.02 W m 1 r-1 TP-2 •r.vv.a. 4.50ft. ��. .. .-.�----------- - USDA: Gray Extremely Gravelly Sand. USCS: GP with Sand. 0.32. 43.08 A TP-2 9.00ft. USDA: Gray Slightly Gravelly Sand. USCS: SP. 0.84 2.38 Specimen Identification D100 D60 D30 D10 LL PL PI %Silt %Clay • TP-1 4.0ft. 37.5 19.552 0.646 0.296 0.9 m TP-2 4.5ft. 37.5 13.653 1.176 0.315 0.2 A TP-2 9.0ft. 19 0.592 0.353 0.249 0.1