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REVIEWED BLD-RESUB 2-Geotech InfiltrationiHA. R TCR 0 WSE R A division of Haley & Aldrich October 18, 2021 Todd Stine 21702 98th Avenue West Edmonds, WA 98020 REVIEWED BY CITY OF EDMONDS • BUILDING DEPARTMENT Re: Recommendations for Residential Drainage and New Construction Support Revised After City of Edmonds Review 19601-00 Dear Todd: RESUB Oct 21 2021 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT This letter summarizes the results of the test pit explorations and pilot infiltration tests (PITS) completed in the yard west of your home at 21702 98th Avenue West, in Edmonds, Washington. Based on those results and on our discussions with you and KPFF, we have prepared specific recommendations to improve the drainage of groundwater and surface water in the yard, and to provide appropriate support for the planned new construction. This letter also addresses the stabilization of the south slope in accordance with the requirements of ECDC 23.80.050, 060, and 070 for geologically hazardous areas. Explorations Eleven test pits (TP-1 through TP-11) were completed throughout the property to investigate the lithology and subsurface conditions (Figure 1— Site Plan and Table 1—Test Pit Information and Soil Descriptions). Soil encountered in the pits consists of three main lithologic units: dark brown sandy silt (fill), orange -brown sandy silt with gravel, and gray, very dense sandy silt with gravel (till). Fill is comprised of dark brown sandy silt with occasional brick, concrete, debris, or fabric fragments. Fill throughout the property was observed to approximately 1 to 2 feet below ground surface (bgs). Orange - brown sandy silt with gravel was encountered below the fill, with varying thicknesses ranging from 2.6 feet bgs, observed in the western part of the property (TP-1 and TP-5) to 8.5 feet bgs, observed in the eastern part of the property (TP-11). This material probably represents a weathered upper portion of the till below. Gravel, cobbles, and boulders were present in some test pits. Till, very dense, gray sandy silt with gravel, was observed at varying depths throughout the property. Till was encountered at shallower depths, ranging from 2.4 feet to 3.6 feet bgs, in the western part (TP-5 and TP-6), and deeper depths, ranging from 7 feet to 8.5 feet bgs, in the eastern part (TP-10 and TP-11). The change in elevation of the top of the dense till unit generally follows the change in elevation of the ground surface, with higher till and surface elevations in the eastern part of the property, and lower till and surface elevations in the west. 3131 Elliott Avenue, Suite 600 Seattle, Washington 98121 206.324.9530 A ALE Todd Stine October 18, 2021 19601-00 Page 2 These same lithologic units and trends were also observed in the slope along the southern edge of the property. Till was encountered at 2.4 feet bgs in TP-5, 3.6 feet bgs in TP-6, and 2 feet bgs in TP-9, suggesting the southern slope is naturally occurring. Groundwater was encountered at 2.5 feet bgs (TP-1) and 0.7 feet bgs (TP-2) in the western part of the property, adjacent to the seasonal pond, suggesting that the seasonal pond is hydrogeologically connected to the groundwater table. Groundwater or perched groundwater was also encountered at 2.6 feet bgs (TP-7), 4 feet bgs (TP-8), and 6 feet bgs (TP-10), suggesting the groundwater is flowing west toward the seasonal pond. Seeping water was also encountered in the test pits along the southern slope (TP-5, TP-6, and TP-9), which then appeared to flow westward at the toe of the slope, suggesting that groundwater or perched groundwater is flowing from the south to the northwest, toward the seasonal pond. We were not able to dig through the water, so we cannot tell if the groundwater on the west is a broader water table or a significant perched zone above the low permeability till. Table 1 — Test Pit Information and Soil Descriptions Additional Soil DepthSymbol Elevation Group Name Density Moisture Color Identification (feet bgs) Comments Test Pit 1 335.3 0 — 0.4 ML Sandy Silt moist dark brown [FILL] Sandy Silt with few cobbles, 334.9 0.4 — 0.9 ML moist orange -brown Gravel scattered wood Sandy Silt with 334.4 0.9 — 2.7 ML moist gray -brown wet at 2.5 feet Gravel Test Pit 2 333.7 0 — 0.7 1 ML Sandy Silt moist dark brown wet at 0.7 feet Test Pit 3 336.5 0 — 1.4 ML Sandy Silt moist dark brown Sandy Silt with 335.1 1.4 ML moist orange -brown occasional roots Gravel Test Pit 4 345.4 0 — 0.2 ML Sandy Silt moist dark brown [FILL] brick fragment at 345.2 0.2 — 1.2 ML Sandy Silt moist brown 1 foot, [FILL] Sandy Silt with 344.2 1.2 — 1.8 ML moist brown Gravel A as Todd Stine October 18, 2021 19601-00 Page 3 Additional Soil Elevation DepthSymbol Group Name Density Moisture Color Identification (feet bgs) Comments 343.6 1.8 - 2.2 MSandy SiltyL moist orange -brown with Gravel Test Pit 5 340 0 - 0.8 ML Sandy Silt moist dark brown scattered roots 339.2 0.8 - 2.4 ML moist gray Sandy Silt with water seepage on Gravel east sidewall Sandy Silt with [very 337.E 2.4 - 3.2 ML moist gray [TILL] Gravel dense] Test Pit 6 scattered roots, filter 339.9 0-1 ML Sandy Silt moist dark brown fabric at just below surface, [FILL] Sandy Silt with water seeping on 338.9 1 - 2.6 ML moist orange -brown Gravel south sidewall Sandy Silt with 337.3 2.6 - 3.6 ML moist gray continued seepage Gravel Sandy Silt with [very 336.3 3.6 - 4.5 ML moist gray [TILL] Gravel dense] Test Pit 7 336.6 0 - 0.6 ML Sandy Silt moist dark brown scattered roots Sandy Silt with 336 0.6 - 1.2 ML moist brown Gravel Sandy Silt with sidewalls caved due 335.4 1.2 - 2.6 ML wet dark brown Gravel to water seepage Test Pit 8 scattered roots, old 339.3 0 - 1.8 ML Sandy Silt moist dark brown car wheel at 1 foot, [FILL] 337.5 1.8 - 2.3 ML Sandy Silt moist black occasional roots Sandy Silt with water seepage at 337 2.3 - 4 ML moist brown Gravel 4 feet Sandy Silt with 335.3 4-6 ML wet gray -brown continued seepage Gravel A as Todd Stine October 18, 2021 19601-00 Page 4 Additional Soil Elevation DepthSymbol Group Name Density Moisture Color Identification (feet bgs) Comments Sandy Silt with [very 333.3 6 ML moist gray [TILL] Gravel dense] Test Pit 9 348 1 0-0.3 1 ML 347.7 0.3-2 ML 346 2 M L 346.2 1 0-2.5 1 ML 343.7 1 2.5-4 1 ML 342.2 4-7 ML 339.2 7 ML 356.6 0 — 0.5 ML 356.1 0.5 — 8.5 ML 348.1 8.5 ML Sandy Silt I I moist Sandy Silt with wet Gravel Sandy Silt with [very moist Gravel dense] Test Pit 10 Sandy Silt moist Sandy Silt with moist Gravel Sandy Silt with wet Gravel Sandy Silt with [very moist Gravel dense] Test Pit 11 Sandy Silt moist Sandy Silt with moist Gravel Sandy Silt with [very moist Gravel dense] scattered roots, dark brown construction debris, [FILL] g ray gray [TILL] few gravel, scattered brown roots some cobbles and boulders, 1.5 feet dark brown diameter boulder at 4 feet water seepage at brown 6 feet gray [TILL] dark brown scattered roots, [FILL] brown occasional roots gray [TILL] A ALE Todd Stine 19601-00 October 18, 2021 Page 5 Pilot Infiltration Testing Near two test pit locations (TP-3 and TP-4), we conducted small scale infiltration tests (PITs) to measure the field infiltration rate of the soil. The general procedures for the small scale PITs consisted of excavating a test cell using a small excavator about 3 feet wide by 3 feet long to a depths of 1.4 to 2.2 feet. The bottom of the test cells were approximately 9 square feet. The constant head portion of the test was conducted by adding water for 2 to 3 hours to the test pit at a rate that will maintain a water level of about 1 foot above the bottom of the pit. The flow rate into the test cell was measured with a bucket test. The rate in gallons per minute (gpm) necessary to maintain the water level was recorded at the end of the tests. The infiltration test performed in PIT-1, adjacent to the seasonal pond, measured a field infiltration rate of 1.8 inches per hour with a flow rate of 4 gallons per minute. The infiltration test performed in PIT-2, in the central part of the property, measured a field infiltration rate of 4.3 inches per hour based on a flow rate of 5 gallons per minute . These infiltration rates are higher than typical for till (approximately 0.5 inch per hour, not measured at this site). Infiltration at this site, in general, is likely limited by the low permeability of the till unit. No restrictive layers above the water table were identified below the bottom of the test cells. To obtain design infiltration rate, a correction factor of 0.33 was applied to the field infiltration rates. The corresponding design infiltration rate are 0.6 and 1.4 inches per hour (Table 2). Table 2 - Summary of Infiltration Test Results Infiltration Test Number Depth (feet bgs) Soil Description Length (feet) Width (feet) Area (Square feet) Field Infiltration Rate (inches/hour) Design Infiltration Rate (inches/hour) Sandy silt with gravel (ML), moist, orange- PIT-1 (TP-3) 1.4 3 3 9 1.8 0.6 brown, with occasional roots Sandy silt with gravel (ML), PIT-2 (TP-4) 2.2 3 3 9 4.3 1.4 moist, orange - brown Notes: A ALE Todd Stine October 18, 2021 a. Design infiltration rate (inches per hour) = field infiltration rate x correction fact (0.33) Yard Drainage Recommendations 19601-00 Page 6 We recommend a three-part solution to the management of groundwater and surface water in the west yard. This area will be partially regraded, but the property to the south will remain at a higher elevation than the west yard. In addition, the property will continue to slope from the east down to the west. Our overall goal is to cut off and redirect as much of the surface and groundwater runoff to infiltration galleries on the upper part of the property before it drains naturally to the west part of the yard. ■ Cutoff Drain Along South Slope — It appears that groundwater and surface water runoff are exiting the slope along much of the south property line and being channeled to the low area on the extreme west side of the property. As part of the regrading, some of this slope will be rebuilt with terraces and short retaining walls. At the back of the retaining walls, we recommend installing 12 inches of free -draining soil (such as City of Seattle Type 17 Bank Run Gravel or approved equivalent) behind the wall, with a minimum 2-inch perforated HDPE collection pipe parallel to the wall at the base. Using short cross drains under the terraced retaining wall, we recommend connecting the back wall drainage to the base of the north wall and installing a second parallel 2-inch drain at the base of the northern -most retaining wall. This drain, in turn, should be connected to the French drains for infiltration across the yard (discussed below). The wall drains should be about a foot deep and surrounded by free draining sand and gravel, such as Type 17. This material typically has a fines content of less than 5 percent by weight and contains at least 30 percent gravel and about 60 percent sand. The maximum gravel size is 3 inches. We recommend the drains be wrapped in a filter fabric sleeve to reduce the potential for clogging or siltation. An additional important benefit of the walls and drains on this slope is the enhanced stabilizing effect it will create both from the terracing and from the drainage of groundwater. Parts of this slope are considered steep under the ECDC 23.80.050 criteria. Terracing the slope with designed walls and collecting and channeling water away with wall drains will improve the overall stability as well as manage the currently uncontrolled groundwater seepage and are in accordance with ECDC 23.80.060 and 070. ■ Infiltrating Trenches Across the Yard — We recommend two sets of shallow infiltration trenches. On the flat graded area at the base of the wall described above extend two lines of trenches diagonally from southwest to northeast at about a 45-degree angle. These lines should be about 30 feet apart, and the western most line should begin about 10 feet east of the top of the west graded downslope (see the sketched approximate location on the attached plan). One or two additional lines of infiltration trenches could be installed on the upper portions of the newly contoured yard. The upper trenches could receive the overflow from the new planned cistern or any hard scape runoff. The infiltration trenches should be constructed in a shallow trench about 2 feet wide and 2 feet A ALE Todd Stine October 18, 2021 19601-00 Page 7 deep. The bottom of the trenches would include at least 4 inches in diameter of perforated HDPE. For maximum infiltration the trenches should be backfilled with free -draining gravel, such as City of Seattle Type 4 (1-1/2-inch Washed Gravel) or approved equivalent. This material has a very low allowable sand content. At the top of the trench, 6 inches of organic topsoil can be placed to allow grass to take root and grow over the drains. We recommend placing a separation filter fabric over the top of the trench in such areas. We further recommend that the infiltration drain pipes not be directly connected to the storm drain system. ■ Lower Infiltration Area — It is difficult to predict how much water will find its way to the low western section of the yard with the new grading and enhanced drainage in place. It seems like it will be less than the volume that collects in the "pond" around the tree during the winter months. An average flow of about 3 gallons per minute is probably an upper bound except during heavy or prolonged precipitation events. The third part of the site drainage plan is to create a below -grade gravel storage and infiltration area to replace the pond. Since our test pits show low permeability soil within just a few feet of the ground surface and a high-water table (at least seasonally) in this area, we recommend the storage and infiltration area be shallow — perhaps only about 2 feet below grade — and exposed at the ground surface. The area extent can be estimated by KPFF, and the storage and infiltration area can be augmented with planting zones for trees or shrubs, if desired. Again, a typical backfill of Type 4 gravel will provide storage and will keep the surface stable. Grading and Backfill Note that the specific gradation requirements for the City of Seattle backfill types referenced in this letter report are in Section 9-03 Aggregates, page 9-22 of the 2020 City of Seattle Standard Specifications for Roads, Bridges, and Municipal Construction. If the yard regrading is done during the drier summer months, it should be possible to reuse the sandy site soils, especially the upper materials above the dense glacial till. If additional material is needed, then a traditional imported sand and gravel, such as the City of Seattle Type 17 or the less gravelly Type 15 pit run sand can be used. As long as the material is not fine grained, is placed in lifts of 12 inches or less, and is rolled or tracked into place it should be firm enough for a recreational area. Subgrade for Structures and Pavement For new exterior drive areas or paved patios, we recommend the subgrade consist of a minimum of 2 feet of either native non -organic soil recompacted in place, or imported fill placed in lifts and compacted to a firm and non -yielding condition. For concrete slabs or driveways, the upper 4 inches of subgrade must consist of a clean, well -graded sand and gravel fill to provide a capillary break. For the garage slab -on -grade, we specifically recommend a subgrade of 2 feet of imported and compacted fill, with the capillary break included. For the new garage foundations, we similarly recommend they be Todd Stine October 18, 2021 19601-00 Page 8 placed either on the native very dense glacial till or on a minimum thickness of 2 feet of imported well - compacted granular fill above a recompacted base of native soil. We recommend footings for the garage be designed for a maximum allowable bearing pressure of 2,000 pounds per square foot. Our representative should be at the site intermittently during construction to provide geotechnical "special inspection" as we observe the installation of all drains and infiltration trenches, the new terraced retaining walls, and the subgrade below hardscapes. Hart Crowser, a division of Haley & Aldrich prepared this letter and these recommendations in accordance with our proposal dated February 5, 2021, our subsequent discussions, and with generally accepted geotechnical engineering practices for the nature and conditions of the work completed in the same or similar localities, at the time the work was performed. We make no other warranty, express or implied. Please contact us if you have any questions. Sincerely, HART CROWSER, A DIVISION OF HALEY & ALDRICH w,�j:, j6It coo ✓�//��Z� tom/ � CIS'IEn" �sS�nNAL �G� DAVID G. WINTER, PE BECCA DOZIER General Manager Senior Staff Hydrogeologist Attachments: Figure 1— Boundary and Topographic Survey Figure 2 — Plan, Site \\haleyaldrich.com\share\sea_projects\Notebooks\1960100_Stine Residence_Drain_Field\Deliverables\letters\Recommendations Letter\2021-1018-HCHA-Stine Recommendation Letter -Oct Revised.docx 215"' PL SW I 337,4 33�x7 ' TP-7 337�0 --_-- -- 359X5 U4 r 1 r S - 11 335,c0 — —x—'mac x—x / x=x—x � x—x _ _ ` ` / , x x—x x- � X —� 33 x�-- - - - ' - _ 29 01 , �� // x - z x 334,c6 335x4 � 1 10w i r ' 354,,5 SH �s9 0 �, 35Ni / r i 1 , 1 D� i i\ r r 3� TP-2 W'y 16a`PLANTER i ��```3 2� 3638LO 1 336x2 3 338, 3 oNo334x1 .:� 33 i '1 340,f8 i ` ait34x6 � � / 0 3 �` // , `�� ` i / 357x7; 1 1 1 z I // 335x5 ; 33 M9,�3 , 343x2 , ^� , r 10 ` ° �/ 1 r ^� 1 r i 3 r l 1 ' $ / - - OND r�`�A 4 , �, r 3�18K5 `14� 35 r 1 ; 3 r 3 3x9 r 1 1 1 r '9 1 $s 1 ' �� i' /� /� i' 342 1 i / 1 1 DECK 334,c5 0� _ i,' ,/ ' ,' 339,46 ,' i' i 3144x ' / �� / / 1 1 1 PATIO ,337,c6 ,. GRASS ,' �. 34,2,(4 �i �/ ,' 347x5 52 �D112 ' GRASS i 357x# I 336,5 � � 3 6x'1 ' 1 1 ,' ,'�47x5 '� I 1 11 1 / B ,� i i , , . '3b�c41 391x4/ , 1 3 �'S43A1 344,7 34 �/ ,' �� r r l 1 3 341,c2 / r / / , , SDMH RIM 356.46 ! 1 1 / _ - - - - - - 336x6 ^ _�_ _ `, _ r CONC. ELKS. i 1 i36�Fx4 334x6 I — _ _ 33 r, ' ' _ �' �' _ _ _ _ _ _ / — _ _ _ 'r 35 356,c3 r r /64�ic2 45_- _ 1 3j,3/ 35— _ A 6x6 , 35 3 _ �41R -' �'��''�'357,A, a0 00 r i 364, 33---- 34 -- _- -- __ _ - x < 354!- 296.98'''_- ,, ' 364x71 365,E 355 _ __ N 88'52'59 W" 346 , TP-3 -'3 - - ----- _- 357,7 --��- �360 ROCKSFDDECK CONC. o ; ; / 4.97 3620 HOU 35�x2 ' S8,c3 - ,- #2135 1 11 358x5 . O TP-5 f- = approximate location of test pits = approximate location of PIT tests (infiltration tests) 338,3 337,,9 TP-6 35M I ` 1 I ` 1 1 � I ARBOR\- 352x2/ 1 1 TP-11 x— GRAPHIC SCALE 20 40 ( IN FEET ) I INCH = 20 F-F. LEGEND © MONUMENT IN CASE • FOUND 1 /2" REBAR WITH CAP LSA SET BRASS SCREW W/WASHER LS 29539 ID ELECTRIC METER / VAULT FIRE HYDRANT ® GAS METER 0 SAN. SEWER CLEAN OUT 0 SAN. SEWER MANHOLE STORM DRAIN MANHOLE -0- UTILITY POLE 9� UTILITY POLE WITH LIGHT & DROP N VALVE ® WATER METER ASPH ASPHALT DW DRIVEWAY LAND SURVEYOR'S CERTIFICATE E ELECTRICAL POWER G GAS THIS MAP CORRECTLY REPRESENTS A SURVEY MADE BY ME OR UNDER MY DIRECTION IN CONFORMANCE WITH THE REQUIREMENTS OF THE SURVEY RECORDING ACT AT THE REQUEST OF TODD STINE IN MARCH, 2019. UY G Asti 'QF� o cn z �3 o �-, 29539 ems' �FG / STERF'� �J S��NAL L AND CERTIFICATE NO. 29539 REVISIONS DESIGNED BY RG DRAWN BY DATE PRINTED 3/27/2019 3:36:34 PM SCALE 1 " = 20' F.B. NO. DATA-C GENERAL NOTES IC LEGAL DESCRIPTION APN: 27032500109900 THAT PORTION OF THE SOUTHWEST QUARTER OF THE NORTHEAST QUARTER OF SECTION 25, TOWNSHIP 27 NORTH, RANGE 3 EAST, W.M., DESCRIBED AS FOLLOWS: BEGINNING AT THE NORTHEAST CORNER OF SAID SOUTHWEST QUARTER OF THE NORTHEAST QUARTER; THENCE SOUTH 0'35'56" WEST 331.74 FEET; THENCE NORTH 88'52'55" WEST 683.98 FEET TO THE TRUE POINT OF BEGINNING; THENCE SOUTH 0'33'15" WEST 82.96 FEET; THENCE NORTH 88°53'09" WEST 296.95 FEET; THENCE NORTH 0'31'59" EAST 82.98 FEET; THENCE SOUTH 88'52'55" EAST 296.99 FEET TO THE TRUE POINT OF BEGINNING. (ALSO KNOWN AS NORTH HALF OF TRACT 35, ONAVU PARK DIVISION NO. 2, UNRECORDED PLAT THEREOF). SITUATE IN THE COUNTY OF SNOHOMISH, STATE OF WASHINGTON. THIS SURVEY WAS CONDUCTED WITHOUT THE BENEFIT OF TITLE REPORT AND THEREFORE DOES NOT PURPORT TO SHOW ALL EASEMENTS, RESTRICTIONS, RESERVATIONS, AND RIGHTS OF RECORD IF ANY. EQUIPMENT AND PROCEDURES WAC 332-130-100 ALL MEASUREMENTS WERE MADE WITH AN ELECTRONIC THEODOLITE WITH A ONE SECOND HORIZONTAL AND VERTICAL DISPLAY AND MANUFACTURES STANDARD POINTING DEVIATION OF THREE SECONDS AND AN ELECTRONIC DISTANCE MEASUREMENT DEVICE WITH A STANDARD DEVIATION OF 3MMf 3PPM, AND CHC X900 RTK GPS. ALL MEASUREMENTS ARE GROUND DISTANCES. GPS ONLY USED AS A BENCHMARK. FIELD TRAVERSE METHOD EXCEEDS W.A.C.'S 332-130-070, 332-130-090 & (GPS) 332-130-080. ALL POINTS INDICATED FOUND WERE VISITED IN 9-2019 UNLESS OTHERWISE NOTED. N CITES: IE INVERT ELEVATION REFERENCE SURVEYS SEE RECORDERS -AUDITORS FILE NUMBERS 201412125006 MEAS. MEASURED 1' CONTOUR INTERVAL, ACCURACY EXCEEDS 112 CONTOUR INTERVAL. OHP OVERHEAD POWER P PLAT ALL UTILITIES WHERE PLACED WITH HELP OF CITY SEWER CARD INFO WATER LINES WITH S SEWER VALVES AND METERS, GAS LINES MAPS FROM PUGET SOUND ENERGY. SHD SHED SPRING WITH FLOWING WATER W WATER CONIFEROUS TREE © WATER DISSIPATES TRUE EXTENT OF CANOPY NOT SHOWN NW-- NE DECIDUOUS OR ORNAMENTAL EVERGREEN TREE ZONING RS-10 ° TRUE EXTENT OF CANOPY NOT SHOWN ; 25 200.0 SPOT ELEVATION IS LOCATED AT THE DECIMAL POINT OF ELEVATION UNLESS NOTED WITH LEADER OR X SW- - SE T BUILDING LINE NOTE: THIS TOPOGRAPHIC SURVEY DRAWING REPRESENTS 600.0 4 SURFACE FEATURES LOCATED ON THE SITE. ANY UNDERGROUND XX_ CHAINLINK FENCE UTILITIES SHOWN ARE BASED SOLELY UPON INFORMATION CENTER LINE SECTION INDEX PROVIDED BY OTHERS EXCEPT AS MEASURED. GREENE LAND S 25, T 27 N, R 03 E, W.M., SURVEYING DOES NOT ACCEPT RESPONSIBILITY OR ASSUME DITCH LINES SNOHOMISH COUNTY, WASHINGTON. LIABILITY FOR UNDERGROUND UTILITY ACCURACY OR COMPLETENESS. --------- EASEMENTS PROPERTY LINE SURVEY CDCZ>� ROCKERY AOO 12 HORIZONTAL DATUM: NORTH 01'06'23" EAST ALONG THE EAST LINE OF THE SOUTH EAST 1 /4 SECTION 19 TOWNSHIP 25 NORTH, RANGE 5 EAST. VERTICAL DATUM: NAVD 1988 PER OPUS SOLUTION FILE: 7GPS079A0.190 OP1553187864771 WITH A STANDARD DEVIATION OF t0.07' -e- GREENE LAND SURVEYING 7408 f 64TH ST SW LYNNWOOD, WA. 98087 PHONE (206) 498-0979 JOB NO. BOUNDARY AND TOPOGRAPHIC SURVEY 2019.14 OF DRAWING NO. HOUSE #21702 98TH AVE W EDMONDS 19-14STINE FOR �:�E E T OF TODD STINE Stine Residence Garage Addition 21702 98th Avenue West Edmonds, WA 98020 4 2 1.21 3 1.21 5 1.21 _ 1.21 En 34 I , EC HouSE FND CK IN L ARBOR # o PLUC OFFSET N N S 8° 9" 8 30' 121 29 %. w .� 357� s USHES x 10' - n ° A 3 16" PLANTER ' 2 F- R. o } o w 404 40 9, o I o �_ C z 3 5X8 -1 o Ln o� s „o a 6„ N O U � x52 r� bEn EIQ 4 �LLJ Q N F- - - o a>>„ a,�o�z 1 _ Lower Infiltration Area -" °` 199 m P 14' 3sszs' rnrl� o I 1.21 3 4,,3 �a�o CONCRETE_ PAD z m � � ..;1 GRAS 348.00, FOR HEAT PUMP 12 3s6.4s' 346.00 PRE S x B 360.33 96' PAS RS RI 9. 344.00' 343.6P 346.33' 3fi 363 341.33'r��� 348.33' 7 . 0.33' 343. 346.33' ' n , ° ' 340 Y _ 353,00' - 42' 343.00' 346.6P _ 366.06' 3 .00' .� 2 3 M 1 3 36 6 � .33' 369.6P 361.6 � 370.26' ° 'C ON 7 211 SHD ' �.� 4.9 7' EC K OUSE 34 , � AB V. #21708 �96 PATIO 4 MAIL BOXES 64, off' O" o P� French Drains Across the Yard Two additional lines Cutoff Drain Along South Slope of French drains could be installed in the upper portions of the yard. The upper drains could receive the overflow from the new planned cistern. 28 FEBRUARY 2021 1 PLAN, SITE �11 1/16"=1'-0" PLAN, SITE 0' 4' 8' 16' 32' M M N O N N Al. I I N