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Geotechnical Evaluation.pdfJuly 29, 2019 ES-6749 Purser Development Services, LLC 520 — 3rd Avenue North Edmonds, Washington 98020 Attention: Mr. Rob Purser Subject: Geotechnical Evaluation Proposed Single -Family Residences 735 —15t" Street Southwest Edmonds, Washington Reference: Northpeak Associates LLC Topographic Survey May 28, 2019 Edmonds City Code (ECC) Geologically Hazardous Areas — Chapter 23.80 Earth Solutions NW" Earth Solutions NW LLC Geotechnical Engineering, Construction Observationjesting and Environmental Seivices RECZ1VED JUL 0" 1 DEVILOP%SENT SERVICES COUNTER Washington State Department of Ecology City of Edmonds Stormwater Addendum (ESA) to the 2014 Stormwater Management Manual for Western Washington (SWMMWW) James P. Minard Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangles Washington, 1983 Dear Mr. Purser: As requested, Earth Solutions NW, LLC (ESNW) has prepared geotechnical evaluation report for the proposed single-family residences. Our scope of services included subsurface investigation, engineering analysis, and preparation of this report with recommendations pertinent to the geotechnical aspects of the project. As part of the subsurface investigation, ESNW observed the excavation of three test pits on June 12, 2019. 1805 - 136th Place N.E., Suite 201 • Bellevue, WA 98005 0 (425) 449-4704 • FAX (425) 449-4711 Purser Development Services, LLC July 29, 2019 Project Description ES-6749 Page 2 The subject site is located at 735 —15th Street Southwest in Edmonds, Washington, as illustrated on the Vicinity Map (Plate 1). The site consists of a single residential tax parcel (Snohomish County parcel number 00390000001100) covering approximately 0.38 acres of land area. The site is currently developed with a single-family residence and associated improvements. The site gently descends toward the northwestern site corner, with about 12 feet of total elevation change. Based our discussions with Client, the existing structure and improvements will be removed and the site will be redeveloped with two new single-family residences and associated improvements. We understand the stormwater design will incorporate infiltration to the extent feasible. Based on the existing grades, we estimate cuts and fills to establish building pad and foundation subgrade elevations will be on the order four to five feet. However, grading plans were not available at the time this report was prepared. At the time this report was prepared, specific building load values were not available. However, we anticipate the proposed residential structures 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 two kips per linear 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 report have been incorporated into the plans. Subsurface Conditions As part of this geotechnical evaluation, an ESNW representative observed, logged, and sampled three test pits on June 12, 2019, excavated at accessible locations within the proposed development area, using a mini-trackhoe and operator retained by our firm. The approximate locations of the test pits are depicted on Plate 2 (Test Pit Location Plan). Please refer to the test pit logs (attached) 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 six inches below existing grades. The topsoil was characterized by dark brown color and fine organic material. Some root zones were observed to extend below the topsoil. No fill was encountered within the test pit locations. If fill is encountered during construction, ESNW should be consulted to verify the suitability for support of the proposed structure and/or reuse as structural fill. Earth Solutions NW, LLC Purser Development Services, LLC July 29, 2019 Native Soil ES-6749 Page 3 Underlying topsoil, native soils were encountered as poorly graded sand with gravel, poorly graded sand with silt and gravel, and poorly graded gravel with silt and sand (USCS: SP, SP-SM, and GP -GM, respectively), consistent with the typical makeup of outwash deposits. The native soil deposits were observed to be generally in a medium dense condition beginning at depths of approximately one to two feet below existing grades and were generally damp to moist at the time of our exploration. Geologic Setting Geologic mapping of the area indicates the site is underlain by Vashon advance outwash deposits (Qva). According to the geologic map resource, the advance outwash is characterized as a well - sorted sand and gravel. The referenced WSS resource identifies Everett very gravelly sandy loam (Map Unit Symbol: 17) as the primary soil unit underlying the subject site. The Everett series was formed in esker, moraines, and kames. Based on our field observations, native soils on the subject site are consistent with outwash deposits. Groundwater Groundwater seepage was not encountered at the test pit locations at the time of our June 2019 subsurface exploration. However, perched seepage may be encountered in site excavations depending on the time of the year excavations take place. 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 winter, spring, and early summer months. Geologic Hazard Areas Assessment Based on review of ECC 23.80, the subject site is not mapped within, or adjacent to, any geologically hazardous areas. Based on our subsurface exploration performed at the subject site, it is our opinion the site is properly mapped outside of ECC geologically hazardous areas. Foundations The proposed residential structures can be supported on conventional continuous and spread footing foundations bearing on competent native soil, recompacted native soil, or new structural fill placed directly on competent native soils. Competent native soil suitable for support of foundations will likely be encountered beginning at depths of about two to four feet below existing grades. Where loose or unsuitable soil conditions are exposed at foundation subgrade elevations, compaction of soils to the specifications of structural fill, or overexcavation and replacement with suitable structural fill, will be necessary. Earth Solutions NW, LLC Purser Development Services, LLC ES-6749 July 29, 2019 Page 4 Provided the foundations will be supported as prescribed, the following parameters may be used for design: Allowable soil bearing capacity 2,500 psf Passive earth pressure a Coefficient of friction 300 pcf (equivalent fluid) 0.40 A one-third increase in the allowable soil bearing capacity may be assumed for short-term wind and seismic loading conditions. The above passive pressure and friction values include a factor - of -safety of 1.5. With structural loading as expected, total settlement in the range of one inch and differential settlement of about one-half inch is anticipated. The majority of the settlements should occur during construction, as dead loads are applied. Seismic Design The 2015 International Building Code recognizes the American Society of Civil Engineers (ASCE) for seismic site class definitions. In accordance with Table 20.3-1 of the ASCE Minimum Design Loads for Buildings and Other Structures manual, Site Class D should be used for design. The referenced liquefaction susceptibility map indicates the subject site possesses low liquefaction susceptibility. Liquefaction is a phenomenon where saturated and loose sandy soils suddenly lose internal strength and behave as a fluid. This behavior is in response to increased pore water pressures resulting from an earthquake or other intense ground shaking. In our opinion, site susceptibility to liquefaction may be considered low. This opinion is based on the composition of the native soil and the absence of evidence of a shallow groundwater table. Slab -on -Grade Floors Slab -on -grade floors for the proposed structures should be supported on competent and well - compacted, firm and unyielding subgrades. Unstable or yielding subgrade areas should be recompacted, or overexcavated and replaced with suitable structural fill, prior to slab construction. A capillary break consisting of at least four inches of free -draining crushed rock or gravel should be placed below each slab. The free -draining material should have a fines content of 5 percent or less (where the fines content is defined as the percent passing the Number 200 sieve, based on the minus three -quarter -inch fraction). In areas where slab moisture is undesirable, installation of a vapor barrier below the slab should be considered. If a vapor barrier is to be used, it should be a material specifically designed for use as a vapor barrier and should be installed in accordance with the specifications of the manufacturer. Earth Solutions NK LLC Purser Development Services, LLC July 29, 2019 Retainina Walls ES-6749 Page 5 Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The following parameters may be used for design: Active earth pressure (unrestrained condition) O At -rest earth pressure (restrained condition) • Traffic surcharge (passenger vehicles) C Passive earth pressure O Coefficient of friction C Seismic surcharge Where applicable * Where H equals the retained height (in feet) 35 pcf (equivalent fluid) 55 pcf 70 psf (rectangular distribution)* 250 pcf (equivalent fluid) 0.40 6H psf** The passive earth pressure and coefficient of friction values include a safety factor of 1.5. The above design parameters are based on a level backfill condition and level grade at the wall toe. Revised design values will be necessary if sloping grades are to be used above or below retaining walls. Additional surcharge loading from adjacent foundations, sloped backfill, or other relevant loads should be included in the retaining wall design. Retaining walls should be backfilled with free -draining material that extends along the height of the wall and a distance of at least 18 inches behind the wall. The upper 12 inches of the wall backfill may consist of a less permeable soil, if desired. A sheet drain may also be considered in lieu of a free -draining backfill section. A perforated drainpipe should be placed along the base of the wall and connected to an approved discharge location. A typical retaining wall drainage detail is provided on Plate 3. If drainage is not provided, hydrostatic pressures should be included in the wall design. Drainage Groundwater seepage may be encountered in site excavations depending on the time of year grading operations take place. ESNW should be consulted during earthwork activities to further evaluate groundwater conditions and provide additional recommendations. Finish grades must be designed to direct surface drain water away from structures and slopes. Water must not be allowed to pond adjacent to structures or slopes. In our opinion, foundation drains should be installed along building perimeter footings. A typical foundation drain detail is provided on Plate 4. Earth Solutions NW, LLC Purser Development Services, LLC July 29, 2019 Infiltration Feasibility ES-6749 Page 6 Our evaluation of site infiltration capacity was completed in general accordance with applicable requirements and procedures of the ESA, to the extent practicable. Two small-scale Pilot Infiltration Tests (PIT) were performed within accessible areas of the subject site during our June 2019 subsurface exploration. One PIT was performed within TP-2 at a depth of about three feet bgs and one PIT was performed within TP-3 at a depth of about three and one-half feet bgs. In accordance with USDA textural analysis, native soils at the bottom of the PITs classified as very gravelly sand and very gravelly coarse sandy loam, with fines contents ranging between about 5 and 10 percent. The following measured infiltration rates and correction factors should be used for design of proposed infiltration facilities: • Short-term (measured) infiltration rate 24 inches per hour • CFI (site variability) 0.67 • CFT (test method) 0.50 (small-scale PIT) • CFM (plugging) 0.90 (typical) • Long-term (design) infiltration rate 7.2 inches per hour Based on our field observations, the following is offered: In accordance with the ESA, the native material is feasible for infiltration design. We acknowledge that final site layouts and/or designs may affect infiltration feasibility, concerning maximum allowable setbacks from structures and property lines. • Infiltration trenches and drywells may be sized for medium sands. ESNW should have the opportunity to review final drainage plans. ESNW should also be retained to observe installation of site infiltration facilities. Supplementary recommendations may be provided at the time of construction, where warranted. On -site Stormwater Management 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. 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. Earth Solutions NW, LLc Purser Development Services, LLC July 29, 2019 ES-6749 Page 7 BMP Viable? Limitations or Infeasibility Criteria Lawns and Landscaped Areas T5.13: Post -construction soil quality and None. No slopes greater than 33 Yes depth Volume V, Chapter 5 percent are present. Roofs T5.30: Full dispersion (Volume V, Chapter The proposed project will not 5) No preserve at least 65 percent of the site. Downspout infiltration systems can T5.10A: Downspout full infiltration systems (Volume III, Chapter 3) Yes be sized based on medium sand soils or 7.2 inches per hour. T7.30: Bioretention (Volume V, Chapter 7) Infiltrating bioretention and rain T5.14A: Rain Gardens (Volume V, Yes garden systems can be sized based Chapter 5) on medium sand soils or 7.2 inches per hour. T5.10B: Downspout dispersion systems NO Proper setbacks and vegetated flow Volume III, Chapter 3 paths are not available. T5.10C: Perforated stub -out connections Yes None. Volume III, Chapter 3 Other Hard Surfaces The proposed project will not Chapter T5.30: Full dispersion (Volume V, p 5) No preserve at least 65 percent of the site. Infiltration surface must be T5.15: Permeable pavement (Volume V, Yes advanced to suitable soils Chapter 5) anticipated at depths below one to two feet. Infiltrating bioretention and rain T7.30: Bioretention (Volume V, Chapter 7) T5.14A: Rain Gardens (Volume V, Yes garden systems can be sized based Chapter 5) on medium sand soils or 7.2 inches per hour. _ Sheet flow dispersion and T5.12: Sheet flow dispersion concentrated flow dispersion may T5.11: Concentrated flow dispersion No be feasible; however, proper (Volume V, Chapter 5) setbacks and vegetated flow paths may not be available. Earth Solutions NW, LLC Purser Development Services, LLC July 29, 2019 Limitations ES-6749 Page 8 The recommendations and conclusions provided in this geotechnical evaluation report 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 Kyler T. Kelly Staff Geologist Attachments: Plate 1 — Vicinity Map Plate 2 — Test Pit Location Plan Plate 3 — Retaining Wall Drainage Detail Plate 4 — Footing Drain Detail Test Pit Logs Grain Size Distribution h a OZ 1 ~tq 53803 � SIONAL 1 � �i%'�b7fK Henry T. Wright, P.E. Senior Project Manager cc: RAM Engineering, Inc. Attention: Mr. Rob Long, P.E. (Email only) Earth Solutions NW, LLC -�M _�i y... _._ s� �r�i 1z .ch r s I Lv_m!i516 s, C.- 26 _� 1►Alyi 1Ui1 alUi �, .� url :!� •7i Wll r .,u„30 YSN j 3 4 •i M'r� OJ. I 3 n `'yF r�. Q s i ,ro sl o 1JIS1r9A.x I R'KiYi.r%O ra wog.. r _ € a.2Uwr r to _ W ►t" _ : r. 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(fNt�t74y� afAny,rtn+ _ PARK I' �_ I/rrr"ir�9 r-., ,rra+sr 6 i'11lrx ` �.;}i � IAi",i�•Sl '� ^�g.� �aa � h. 511�•N {1�bj � F �$ r.vt 1� i t 1r• s l�t�'t < c S a, i loot I" Mg Ifi d r r •'�tr 12 i�$ ...,rtif Y. r s u0/3rrNff if a u.l' i=t, Ii tin 0 !1 •1. _� �t' ' � S L_. ss.tc- M Y�YI+ cJ � w Sf llJ' rt ii Z� �� ,}7ni01 r �� ' w • �nl kntP-.bN t „ Pill �'t •. IF v v Reference: NORTH Snohomish County, Washington Map 474 By The Thomas Guide Rand McNally Vicinity Map 32nd Edition 735 — 15th Street S.W. Edmonds, Washington NOTE: This plate may contain areas of color. ESNW cannot be Drwn. MRS Date 06/25/2019 Proj. No. 6749 responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. Checked KTK Date June 2019 Plate 1 X13U v adi�TP-2 � T I I TP=1 LEGEND TP-1 I Approximate Location of — ■ — ESNW Test Pit, Proj. No. ES-6749, June 2019 Subject Site Existing Building NOTE: The graphics shown on this plate are not intended for design purposes or precise scale measurements, but only to illustrate the approximate test locations relative to the approximate locations of existing and / or proposed site features. The information illustrated is largely based on data provided by the client at the time of our study. ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. NOTE: This plate may contain areas of color. ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black & white reproductions of this plate. 0 25 1 "=50' M! W Earth Solutions NWuc �Jj J Z L.1.1 Q 00 t I I I I I I 1 I 50 100 Scale in Feet Test Pit Location Plan 735 — 15th Street S.W. Edmonds, Washington Drwn. MRS Date 06/25/2019 Proj. No. 6749 Checked KTK Date June 2019 Plate 2 III -HE III r, NOTES: 18" Min. 00 0 o 0 o o 0o o v0 o 00 o Oo o 00� 000 0 0 00 00 00 0 00 0 000 0 0 0 0 00 0000 00 q00 0 0 0 o00.0 0 0 0 0 o V o o O 00 0 o g D o 0 0 0 - 0 0 0 O o 00 0 00 00 0 0 0 000 0 0 0:0.000 00 0 0 0 00 0 00 0 0 0 0Q 00 0 0 00 0 0 0.(5 0 0 0 0 O 0O00 0 0 0 00 0 0 0 o, o 0 0 oA O0 OO- O 0 .0 'o ' O 6 011 c 0 0 0 0 0g O , 0 00 0 0O 0 00 o GO O 0 o 0 0 00 0 00 o 0 0 0 00 0 0 00 0 0 0 0 B0 0 0 Oo 0 O0o 0 .0 0 0 , o • Free -draining Backfill should consist of soil having less than 5 percent fines. Percent passing No. 4 sieve should be 25 to 75 percent. • Sheet Drain may be feasible in lieu of Free -draining Backfill, per ESNW recommendations. • Drain Pipe should consist of perforated, rigid PVC Pipe surrounded with 1-inch Drain Rock. LEGEND: 000 0 0 op oo Free -draining Structural Backfill 1-inch Drain Rock Structural Fill Perforated Rigid Drain Pipe (Surround in Drain Rock) SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING Earth Solutions NW LLc Retaining Wall Drainage Detail 735 — 15th Street S.W. Edmonds, Washington Drwn. MRS Date 06/25/2019 Proj. No. 6749 Checked KTK Date June 2019 1 Plate 3 NOTES: • Do NOT tie roof downspouts to Footing Drain. • Surface Seal to consist of 12" of less permeable, suitable soil. Slope away from building. LEGEND: Surface Seal: native soil or other low -permeability material. E'e"M 1-inch Drain Rock Perforated Rigid Drain Pipe (Surround in Drain Rock) SCHEMATIC ONLY - NOT TO SCALE NOT A CONSTRUCTION DRAWING Earth Solutions NW 11( Footing Drain Detail 735 — 15th Street S.W. Edmonds, Washington Drwn. MRS Date 06/25/2019 Proj. No. 6749 Checked KTK Date June 2019 Plate 4 Earth Solutions NWLLC SOIL CLASSIFICATION CHART SYMBOLS TYPICAL MAJOR DIVISIONS GRAPH LETTER DESCRIPTIONS CLEAN ir.qr WELL-GRADED GRAVELS, GRAVEL - GRAVEL GRAVELS w'%. b GW SAND MIXTURES, LITTLE OR NO ' FINES AND o�o GRAVELLY SOILS (LITTLE OR NO FINES) GP POORLY -GRADED GRAVELS, GRAVEL- SAND MIXTURES, LITTLE ,(3 (1 O OR NO FINES COARSE °a ° °0 ° GRAINED GRAVELS WITH GM SILTY GRAVELS, GRAVEL -SAND - SOILS MORETHAN50% FINES O D SILT MIXTURES OF COARSE o FRACTION RETAINED ON NO. 4 SIEVE (APPRECIABLE GC CLAYEY GRAVELS, GRAVEL- SAND - AMOUNT OF FINES) CLAY MIXTURES CLEAN SANDS SW WELL -GRADED SANDS, GRAVELLY MORE THAN 50% SAND SANDS, LITTLE OR NO FINES OF MATERIAL IS AND SP POORLY -GRADED SANDS, GRAVELLY SAND, LITTLE OR NO LARGER THAN NO. SIEVE SANDY SOILS SIZE SIZE (LITTLE OR NO FINES) FINES SANDS WITH SM SILTY SANDS, SAND - SILT MORE THAN 50% FINES MIXTURES OF COARSE FRACTION PASSING ON NO. 4 SIEVE (APPRECIABLE SC CLAYEY SANDS, SAND - CLAY AMOUNT OF FINES) MIXTURES INORGANIC SILTS AND VERY FINE ML SANDS, ROCK FLOUR, SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITH SLIGHT PLASTICITY SILTS INORGANIC CLAYS OF LOW TO FINE AND LIQUID LIMIT CL MEDIUM PLASTICITY, GRAVELLY GRAINED CLAYS LESS THAN 50 CLAYS, LEAN CLAYS CLAYS,CLAYS, SANDY SILTY SOILS _ _ OL ORGANIC SILTS AND ORGANIC — — — SILTY CLAYS OF LOW PLASTICITY MORE THAN 50% INORGANIC SILTS, MICACEOUS OR OF MATERIAL IS MH DIATOMACEOUS FINE SAND OR SMALLER THAN SILTY SOILS NO.200 SIEVE SIZE SILTS AND LIQUID LIMIT CH CLAYS OF HIGH GREATER THAN 50 PLASTICITY CLAYS OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY. ORGANIC SILTS HIGHLY ORGANIC SOILS AL, 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 PROJECT NUMBER ES-6749 PROJECT NAME 735 —15th Street_S_.E_. DATE STARTED 6/12/19 COMPLETED 6/12/19 GROUND ELEVATION 282 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating _. GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION LOGGED BY KTK CHECKED BY HTW AT END OF EXCAVATION NOTES Depth of Topsoil _&, Sod _6":_grass _ AFTER EXCAVATION --- I w I I wW w CO TESTS vUi = Q O MATERIAL DESCRIPTION 0 aD Q Z af C7 0 TPSL 0.5 Dark brown TOPSOIL, trace roots to `i _ 2815 Brown poorly graded SAND with silt and gravel, loose, damp -becomes moist SP- -light iron oxide staining to 4', becomes medium dense MC = 9.50% SM MC = 12.50% -minor caving to BOH 4.5 277. b 5 Gray poorly graded SAND with gravel, medium dense, moist MC = 3.00% -increased gravel content SP X MC = 11.80% 7.0 Test pit terminated at 7.0 feet below existing grade. No groundwater encountered during excavation. Caving observed from 3.0 feet to BOH. Bottom of test pit at 7.0 feet. Earth Solutions NW TEST PIT NUMBER TP-2 1805 - 136th Place N.E., Suite 201 ' Bellevue, Washington 98005 PAGE 1 OF 1 Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-6749 PROJECT NAME 735-15th Street S.E. DATE STARTED 6/12119 COMPLETED 6112/19 GROUND ELEVATION 282 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION --- LOGGED BY KTK CHECKED BY HTW AT END OF EXCAVATION --- NOTES Depth of Topsoil & Sod 6": grass AFTER EXCAVATION --- LU Uj a L TESTS U a 6 MATERIAL DESCRIPTION Q Z (� 0 TPSL ' 05 Dark brown TOPSOIL 2y.. 5 Brown poorly graded SAND with silt and gravel, loose, damp SP- SM 20 280,0 ` Gray poorly graded GRAVEL with silt and sand, medium dense, damp to moist = o MC 1,60% ;, -infiltration test at T, minor caving to BOH Fines = 10,40% GP- � [USDA Classification: very gravelly coarse sandy LOAM] GM u 5 MC = 8.90% 1.1 5.0 _ 27,10 Gray poorly graded SAND with gravel, medium dense, moist SP MC = 7.40% 118.5 [USDA Classification: very gravelly SAND] 2/3 ,b Fines = 1.60% Test pit terminated at 8.5 feet below existing grade. No groundwater encountered during excavation. Caving observed from 2.5 feet to BOH. Bottom of test pit at 8.5 feet. 1805 - 136th Place N.E., Suite 201 - Bellevue, Washington 98005 PAGE 1 OF 1 4mEarth Solutions NW TEST PIT NUMBER TP-3 Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-6749 PROJECT NAME 735 — 15th Street S.E. _ DATE STARTED 6/12/19 COMPLETED 6/12/19 GROUND ELEVATION 288 ft TEST PIT SIZE EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS: EXCAVATION METHOD AT TIME OF EXCAVATION - LOGGED BY KTK CHECKED BY HTW AT END OF EXCAVATION - NOTES Depth_ of ToQsoil_ & Sod 6": grass _ AFTER EXCAVATION --- I LU a.� I I U _ w— CO TESTS Uj Q O MATERIAL DESCRIPTION 0 EL Q z C7 U) 0 T PSL 0.5 Dark brown TOPSOIL, trace roots to 5' 287,5 Brown poorly graded SAND with silt and gravel, loose to medium dense, damp MC = 6.00% -moderate iron oxide staining to 3' becomes weakly cemented, becomes moist MC = 16.60% -minor caving to BOH, becomes gray MC = 3.80% SM -infiltration test at 3.5' Fines = 5.30% [USDA Classification: very gravelly SAND] 5 MC = 15.20% 6.0 282.0 Gray poorly graded SAND with gravel, medium dense, moist SP X MC = 5.80% 8.0 [USDA Classification: very gravelly coarse SAND] 280.0 Fines = 1.00% Test pit terminated at 8.0 feet below existing grade. No groundwater encountered during excavation. Caving observed from 2.5 feet to BOH. Bottom of test pit at 8.0 feet. Earth Solutions NW GRAIN SIZE DISTRIBUTION 1805 - 136th Place N.E., Suite 201 Bellevue, Washington 98005 Telephone: 425-449-4704 Fax: 425-449-4711 PROJECT NUMBER ES-6749 PROJECT NAME 735 - 15th Street Southwest U.S. SIEVE OPENING IN INCHES I U S- SIEVE NUMBERS I HYDROMETER 6 4 3 2 1 W 112318 3 4 6 810 1416 20 30 40 50 60 100 140 200 100 95 — 90 - - 85 80 75 - -- - -- - — - 70 - - - - 65 - - - — w — r 55 m - - - w 50 Z - - - LL I- 45 z w 40 w o_ 35 - - - - - - - - - - 30 - — - — 25 - -- --- 20 - - - - 15 — - - r 10 i — - - r 5 - - - - — r 0 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse fine coarse I medium fine Specimen Identification Classification Cc TEU TP-02 3.Oft. USDA: Gray Very Gravelly Coarse Sandy Loam. USCS: GP -GM with Sand. 0.71 388.60 m TP-02 8.5ft. USDA: Gray Very Gravelly Sand. USCS: SP with Gravel. 0.10 35.16 • TP-03 3.5ft. USDA: Gray Very Gravelly Sand. USCS: SP-SM with Gravel. 0.19 25.14 * TP-03 8.Oft. USDA: Gray Very Gravelly Coarse Sand. USCS: SP with Gravel. 0.45 12.93 Specimen Identification D100 D90 D60 D30 D10 ILL PL PI %Silt I %Clay 0 TP-02 3.Oft. 37.5 31.331 14.517 0.622 10.4 m TP-02 8.5ft. 19 15.94 9.126 0.492 0.26 1.6 • TP-03 3.5ft. 19 14.753 5.022 0.442 0.2 5.3 *1 TP-03 8.011. 37.5 29.95 4.625 0.859 0.358 1.0