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REVIEWED-BLD2022-0750+Geotechnical_Report+6.8.2022_11.22.16_AM+2919780mom I LW RILEYGROUP April 22, 2022 Niran Abedalla 10951 Southeast 162"d Street Bellevue, Washington Subject: Infiltration Assessment 7815 202"d Place Southwest Edmonds, Washington RGI Project No. 2022-143-1 As requested, The Riley Group, Inc. (RGI) is pleased to provide the results of our recent infiltration assessment at the above -referenced Site (Figure 1). Our infiltration assessment was completed to estimate infiltration rates in the onsite soils. Subsurface Conditions Review of the Geologic Map of the Edmonds East and part of the Edmonds West Quadrangles, Washington, by James P. Minard (1983) indicates that most of the site is mapped as Till (Qvt), which is a compact mixture of clay, silt, sand, and gravel deposited at the base of the Vashon ice sheet. Soil conditions observed at the site were 10-inches of topsoil, sand with varying amount of silt and gravel to a depth of 10 feet below grade. Very dense gray silty sand was observed at 10 feet below grade. The very dense gray silty sand is interpreted to be Vashon-age lodgment till. Groundwater was not encountered in any of the subsurface explorations. Infiltration Testing Small-scale Pilot Infiltration Test (PIT) IT-1 was completed on the northern portion of the site as shown on Figure 2. The test was completed at a depth of approximately five feet below grade per City of Edmonds protocol. A field rate of 12.9 inches per hour was measured in IT-1. Correction factors per the manual were applied to the field measured rate as described below: Ksatdesign = Ksatinitial = CFv x CFr x CFM CFv = Site Variability (0.33 to 1.0) CFV = 1 CFr = Test Method (Small PIT = 0.5) CFm = Degree of Influent Control (0.9) Total Correction Factor = 1 x 0.5 x 0.9 = 0.45 Ksatdesign = Ksatinitial (12.9 inches/hour) X 0.45 Ksatdesign = 5.8 inches/hour A Ksat design rate of 5.8 inches/hour was calculated with the applied correction factors Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone 425.415.0551 0 Fax 425.415.0311 www.riley-group.com Infiltration Assessment Page 2 April22, 2022 7815 20211 Place Southwest Edmonds, Washington RGI Project No. 2022-143-1 Please call us at (425) 415-0551 if you have any questions or need additional information. Respectfully submitted, THE RILEY GROUP, INC. Hydrogeologist 1079 �hsed Geo�� David John Baumgarten David J. Baumgarten, LHG Associate Hydrogeologist Attachments: Figure 1, Site Vicinity Map Figure 2, Geotechnical Exploration Plan IT-1 Soil Log 1 1 L- RILEYGROUP USGS, 2020, Edmonds East, Washington Approximate Scale: 1"=1000' 7.5-Minute Quadrangle 0 500 1000 2000 N �CorporateOffice Abedalla Residence Figure 1 17522 Bothell Way Northeast RGI Project Number: Date Drawn: Bothell, Washington 98011 Site Vicinity Map Phone: 425.415.0551 2022-143-1 04�2022 ]LEY Fax: 425.415.0311 Address: 7815 202nd Place Southwest, Edmonds, Washington 98026 N: 301317.304 E:1270333.392 \9.T 0�AR/CAP 42' (--)28' `ED W. 301319.314 E:1270414.36 sN'CE F SET NAIL SHN T-5.00_ ro "E4CE y, 20.0'� +S', 32' DEC g 88- - - - z 1 LIAM Q PRO�o OpOO. NOOSE N0. J815 "`' .,y` - oo,o �Sn �51 OornNN7�,.329 -SF. t I% P6' -POOF EL-442 6' Ni - - Q. coNc � r z f L nVEF. •. . 12' CEO / p' ; °•';,` . 71 ,c N:301225.E!! -a N OW42'45' W 1270334.320 :30122&271 -1270413.319 779.(OMO'.'E SS -SAS- __S---S-_q 202ND PL SW 0MH IM-AT9.9 �' = Small scale pit test by RGI, 04/05/22 Approximate Scale: 1"= 20' — — — = Site boundary 0 10 20 40 N �CorporateOffice Abedalla Residence Figure 2 17522 Bothell Way Northeast Bothell, Washington 98011 RGI Project Number: Geotechnical Exploration Plan Date Drawn: 2022-143-1 04/2022 Phone: 425.415.0551 LtYUMffiW Fax: 425.415.0311 Address: 7815 202nd Place Southwest, Edmonds, Washington 98026 Project Name: Abedalla Residence Test Pit No.: TP-1 Project Number: 2022-143-1 Client: Niran Abedalla RILEYGROUP Sheet 1 of 1 Date(s) Excavated: 4/5/2022 Logged By ELW Surface Conditions: Grass Excavation Method: Test Pit Bucket Size: N/A Total Depth of Excavation: 10.5 feet bgs Excavator Type: Mini Excavator Excavating Contractor: Kelly's Excavating Approximate N/A Surface Elevation Groundwater Level: Not Encountered Sampling Grab Method(s) Compaction Method Bucket Test Pit Backfill: Cuttings Location 7815 202nd Place Southwest, Edmonds, Washington n E O H O Z N T to —J U L O O_ co U) Q (6 w 0 <n U) D cD MATERIAL DESCRIPTION REMARKS AND OTHER TESTS 0 TPSL 101, topsoil Fill Brown silty SAND with some gravel, loose to medium dense, moist (Fill) sM Reddish brown silty SAND with some gravel, medium dense, moist Trace organics sM Gray silty SAND with some gravel, medium dense, moist 5 PIT test performed at a depth of 5' in a 2'x5' trench 11 % moisture, 13% fines o 0 10 /o moisture, 12 /o fines SP-SM •• Gray gravelly SAND with some silt, medium dense, moist 10/o o 0 moisture, 13 /o fines sM Gray gravelly silty SAND, medium dense, moist o 0 10 /o moisture, 12 /o fines SP-SM •. Gray SAND with some silt and gravel, medium dense, moist 10 11 %moisture, 21 %fines SM Gray silty SAND with some gravel, dense, moist (Glacial Till) Test Pit terminated at 10.5' The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name: Abedalla Residence Key to Logs Project Number: 2022-143-1 Client: Niran Abedalla RILEYGROUP Sheet 1 of 1 _ O - Q H O E Z N T W 0) _J U > a at E m E a1 U W n w o U)i W D C� MATERIAL DESCRIPTION I REMARKS AND OTHER TESTS COLUMN DESCRIPTIONS 1 Elevation (feet): Elevation (MSL, feet). 2 Depth (feet): Depth in feet below the ground surface. LIJ Sample Type: Type of soil sample collected at the depth interval shown. ® Sample Number: Sample identification number. FIELD AND LABORATORY TEST ABBREVIATIONS CHEM: Chemical tests to assess corrosivity COMP: Compaction test CONS: One-dimensional consolidation test LL: Liquid Limit, percent MATERIAL GRAPHIC SYMBOLS . AF L F1'J Silty SAND (SM) TYPICAL SAMPLER GRAPHIC SYMBOLS Auger sampler CME Sampler Bulk Sample Grab Sample 3-inch-OD California w/ 2.5-inch-OD Modified brass rings California w/ brass liners GENERAL NOTES 5 USCS Symbol: USCS symbol of the subsurface material. L6J Graphic Log: Graphic depiction of the subsurface material encountered. �7 MATERIAL DESCRIPTION: Description of material encountered. May include consistency, moisture, color, and other descriptive text. ® REMARKS AND OTHER TESTS: Comments and observations regarding drilling or sampling made by driller or field personnel. PI: Plasticity Index, percent SA: Sieve analysis (percent passing No. 200 Sieve) UC: Unconfined compressive strength test, Qu, in ksf WA: Wash sieve (percent passing No. 200 Sieve) Poorly graded SAND with Silt (SP-SM) Topsoil Pitcher Sample 2-inch-OD unlined split spoon (SPT) Shelby Tube (Thin -walled, fixed head) OTHER GRAPHIC SYMBOLS Water level (at time of drilling, ATD) • Water level (after waiting) _ Minor change in material properties within a v stratum Inferred/gradational contact between strata — ? — Queried contact between strata 1: Soil classifications are based on the Unified Soil Classification System. Descriptions and stratum lines are interpretive, and actual lithologic changes may be gradual. Field descriptions may have been modified to reflect results of lab tests. 2: Descriptions on these logs apply only at the specific boring locations and at the time the borings were advanced. They are not warranted to be representative of subsurface conditions at other locations or times. The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011