Loading...
The URL can be used to link to this page
Your browser does not support the video tag.
APPROVED STM RESUB4 BLD2023-0692+DRAINAGE REPORT +11.23.2024_9.36.51_AM+4636160
RESUB BLD2023-0692 Nov 25 2024 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT BK Chen Townhouse 7103 210th ST SW, Edmonds WA 98026 Technical Information Report - Drainage Report DF WASH f s J 1� t105A 2183 J 1� 10/25/24 Applicant: Baokai Chen 7103 210th ST SW, Edmonds, WA 98026 BKCHENgGMAIL.COM (206) 331-5725 Project Engineer: Jie Sheng, PE, LEED Green Associate SH Fine Consulting 13608 SE 51st PL, Bellevue, WA 98006 SHFINECONSULTINGna,GMAIL. COM (425)444-9740 Contact Person: Yuanjing Sheng, PE, PhD HomeTech 13608 SE 51st PL, Bellevue, WA 98006 HOMETECHWAa.GMAIL.COM (206) 778-2431 March 10, 2021 Revised October 25, 2024 COMPLIES WITH APPLICABLE CITY STORMWATER CODE Page 1 12/04/2024 Tables of Contents 1. Introduction 3 Figure 1-1: Project Site Area 3 2. Existing Conditions 3 3. Proposed Conditions 4 Table 1-1: Project Impervious Areas 4 4. Proposed Drainage 4 Minimum Requirement #1: Preparation of Stormwater Site Plans 4 Minimum Requirement #2: Construction Stormwater Pollution Prevention 4 Minimum Requirement #3: Source Control of Pollution 4 Minimum Requirement #4: Preservation of Natural Drainage Systems/Outfalls 4 Minimum Requirement #5: Onsite Stormwater Management 5 Table 2-1: Onsite Stormwater Management 6 Minimum Requirement #6: Runoff Treatment 6 Minimum Requirement #7: Flow Control 6 Minimum Requirement #8: Wetland Protections 6 Minimum Requirement #9: Operation and Maintenance 6 Appendix A: Site and Drainage Plans 7 Appendix B: Minimum Requirements 8 Appendix C: Onsite Stormwater Management BMP Selection 9 Appendix D: Infiltration Testing and Geotechnical Report 10 Appendix E: Offsite Analysis 11 Appendix F: Operation and Maintenance Manual 13 Appendix G: WWHM Infiltration Trench Data 14 Page 2 1. Introduction This report analyzes storm water drainage control measures for the proposed BK Chen Townhome project located in the City of Edmonds. The project site consists of a single, rectangular parcel located at 7103 210th ST SW, Edmonds, WA, 98026. The parcel is approximately 11,326 square feet in size, and bounded by access roads to the east and west, private residence to the north and 210th ST SW to the south. There is an existing single -story dwelling unit and carport that will be demolished. The proposed development consists of a 6-unit townhome development. Figure 1-1: Project Site Area 2. Existing Conditions The site is generally flat with gentle slopes from north to south with grades of approximately 5%. There is an existing single -story dwelling unit and carport that will be demolished and removed. Current storm water runoff from the roofs are discharged to the surrounding lawn surface via downspouts and sheet flow from the carport roof. Runoff follows the existing grade of the site towards 210th St SW and into the curb and gutter drainage system along 210th ST SW. Existing driveway runoff sheet flows into the curb and gutter drainage system along 210th ST SW. There is no evidence of downstream flooding and no drainage complaints related to this parcel. Field observations conducted during and after rain events observed no runoff from adjacent sites onto the project site. The project site has roads to the west, east and south that collect stormwater to public drains. No runoff from the north residential property was observed to enter the project site, presumably due to its drainage collection system and the existing lawn. There are no known critical areas onsite or adjacent to the site. Page 3 3. Proposed Conditions The proposed development includes the demolition of the existing structures, and the construction of a new, 6 unit townhome development, and associated walkways and driveways. Refer to Appendix A for the proposed Site Plan. Refer to Table 1-1 below for proposed hard areas. Lot Size Proposed Proposed Proposed New Plus Total PGIS Footprint Driveway Walkway Replaced Hard Surfaces 11,326 SF 4,884 SF 3,133 SF 855 SF 8,872 SF 3,988 SF Table 1-1: Project Impervious Areas Infiltration testing shows this site is suitable for infiltration. Refer to Appendix D for the infiltration test results and procedures. Infiltration BMPs are proposed for this site. Evaluation of all stormwater management BMPs and proposed infiltration facilities are discussed in further detail below. Refer to Appendix A for the proposed drainage plan. 4. Proposed Drainage Drainage analysis for this site was done per the 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) and the City of Edmonds 2019 Stormwater Code and Reference Documents. Per ECDC Section 18.30.060, this project is a Category 2 and shall comply with Minimum Requirements # 1 through #9. Minimum Requirement #1: Preparation of Stormwater Site Plans Stormwater site plans have been prepared for this proposed development and are attached in Appendix A. Minimum Requirement #2: Construction Stormwater Pollution Prevention A Construction Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the Stormwater Site Plan. The SWPPP narrative and drawings are submitted separately. Minimum Requirement #3: Source Control of Pollution All disturbed lawn and landscaped areas shall be restored to Post -Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the DOE Manual and City of Edmonds Stormwater Code Addendum Checklist 7. S411 in Volume IV-4 should also be used for Landscaping and Lawn and Vegetation Management. Refer Appendix C. No other source pollutants are not anticipated at this project site. Minimum Requirement #4: Preservation of Natural Drainage Systems/Outfalls The existing outfall is the public storm system along 210th ST SW. There is an existing curb and gutter system adjacent to the project site that leads to a catch basin in the right of way along 210th ST SW. The Page 4 proposed project maintains this existing outfall to the maximum extent feasible. See Appendix E for existing site and proposed site off -site analysis. Minimum Requirement #5: Onsite Stormwater Management Onsite stormwater management BMPs from ECDC 18.30.060D.5.e List #2 are considered below. Infiltration testing shows this site is suitable for infiltration. Refer to Appendix D for the infiltration test results and procedures. Lawn and Landscaped Areas: All disturbed lawn and landscaped areas shall be restored to Post -Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the DOE Manual and City of Edmonds Stormwater Code Addendum Checklist 7. Refer Appendix C. Roofs: The following onsite stormwater management BMPs are considered for all future proposed roof areas, in order: 1. Full dispersion is not feasible due to lack of native vegetation, and lack of 100-ft minimum flow path. 2. Downspout Full Infiltration Systems in accordance with BMP T5.10A in Section 3.1.1 of Volume III of the SWMMWW is feasible and proposed for this project. Other Hard Surfaces: The following onsite stormwater management BMPs are considered for the proposed driveway, in order: 1. Full dispersion is not feasible due to lack of native vegetation, and lack of 100-ft minimum flow path. 2. Downspout Full Infiltration Systems in accordance with BMP T5.10A in Section 3.1.1 of Volume III of the SWMMWW is feasible and proposed for this project. The infiltration trench is designed to provide 100% infiltration as modeled by the Western Washington Hydrology Model (WWHM) using the geotechnical recommended infiltration rate (refer to Appendix D). WWHM data is included in Appendix G. Overflow is not expected as the infiltration is designed to provide 100% infiltration. Any overflow from exceptional stormwater events to the infiltration trench will follow the lawn grade, flowing east to west towards the proposed driveway, which is graded to drain towards 210th ST SW. There is an existing storm drain that will convey any overflow to the city storm system. The proposed walkways are 4-ft in width and are proposed to be graded to drain runoff away from buildings and towards the vegetated areas via sheet flow dispersion per BMP T5.12 in the DOE manual. Vegetated areas adjacent to the walkways are a minimum of 2-ft in width. Refer to Appendix A for Drainage Plans and Details. Page 5 Hard Surface I Area Proposed BMP Building Footprint 1 4,884 SF Full Infiltration Driveway Walkway Table 2-1: Onsite Stormwater Management 3,133 SF Full Infiltration 855 SF Sheet Flow Dispersion Minimum Requirement #6: Runoff Treatment This project does not generate 5,000 SF or more of pollution -generating hard surfaces or 0.75 acres or more of pollution -generating pervious surfaces. Per ECDC 18.30.060.D.6, runoff treatment is not required. Minimum Requirement #7: Flow Control This project has less than 10,000 SF of total effective impervious surfaces and does not convert 0.75 acres or more of vegetation to lawn or landscape, or 2.5 acres or more of native vegetation to pasture. The proposed infiltration trench has been sized appropriately to keep stormwater runoff from the proposed project onsite. Refer to Appendix G. Per EDCD 18.30.060.D.7, flow control is not required. Minimum Requirement #8: Wetland Protections This project does not contain any known or observed wetlands. Stormwater from this project does not discharge into any known or observed wetlands. Minimum Requirement #9: Operation and Maintenance Operation and maintenance of proposed stormwater BMPs is the responsibility of the owner. Refer to Appendix F for the Operation and Maintenance Manual. Page 6 Appendix A: Site and Drainage Plans Page 7 END OF WALL 3.4' S X 0.4' E D SDMH W/GATE VAVLE o m RIM=410.43 D 36" CMP NW IE=402.96 III I n 12" CMP S IE=403.13 0 . r- M ADDRESS SIGN I f MULTIPLE HOUSES N CB TYPE 1 I I RIM=404.86 N 6" PVC N IE=403.14 6" PVC S IE-403.06 I N N N IJ� SD- SD- �5°.' HOUSE #T113 d'a 4 A - P 6' WOOD 24"- x—x—x—x- -x—x S89 � - 24"-C 30"- -:5U'-F KE—�S ONE WALL ____4_ N LINE SF A\ z 0 ry N C� 0 20"-L V (` 20"-F 'Ilfryyy7.'I� - 2. 4' F III 3 3 m 3 D z � n0 0�z �zo 3 � 0 0 (n �n r� 0 Z 0 c1 n 01 i c�c� 0 m 0 3 c I i � 3 / 1 I uL n 0 : FSS / - - 1.1'IE I APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: BY: LEGEND CITY ENGINEERING DIVISION ® FOUND MONUMENT AS NOTED SET 24" X 1 /2" REBAR WITH "LS CAP STAMPED 32441" FOUND MAG AND WASHER AS NOTED O FOUND IRON PIPE OR REBAR AND CAP (RBC) AS NOTED ® WATER METER WATER VALVE FIRE HYDRANT UTILITY POLE ;CEO UTILITY POLE WITH LIGHT E-- GUY ANCHOR ® MAILBOX SIGN ° GATE POST ® TYPE I CATCH BASIN O STORM DRAIN MANHOLE KIN STORM DRAIN CLEAN OUT O SANITARY SEWER MANHOLE O SANITARY SEWER CLEANOUT — x x— FENCE (TYPE NOTED) 24" I a — c c — GAS —SD SD— STORM DRAIN 18' [F — w w — WATER -R R- OVERHEAD UTILITIES / I 2.5 W -- 3 m D -SS SS- SANITARY SEWER 20"- F r a 3 ` I SIDE SEWER CONNECTION LOCUST (-L) I24"'-F � I � a PER CITY OF EDMONDS < CEDAR C x/ I AS -BUILT DRAWING 22"-F x I'; CB TYPE 1 (SOLID LID) ( ) D RIM=408.59 FIR (-F) - 0.9 E 18" 3 12" GONG W IE=403.30 PINE >, 26"-F 18"-F 1 E 12" GONG N IE=403.24 I` . N 74.20' 3' W - ASPHALT CB TYPE 1 f� ff f �x —x -� GATE 3' W OD FENCE F J 3 \ CONCRETE RIM=405.34 a x x x �x x 12" GONG N IE=402.09 w wLw -`, w w —w—w w w w w w A• w da w P _ 12" GONG S I E= 400.40 = SO SD SD g D- SS- SD D- SD- SD- SD' SD- SD- SD SD Sp- SD- SD- SD SD 12" CONIC E, W IE=400.39 a� 10 MAILBOXES 1. . W I"I ? CB TYPE 1 .. o` EXISTING CONDITION PLAN � RIM=405.40/ p 12" CONG., E IE=402.73 a N 12". CON W IE=402.67 1. i' DASHED YELLOWNSTRIPE 342.72' SCALE: 1" = lo' - ¢FOUND MAG &WASHER FOUND-MAG. WASHER S89°19'20"W 685.43' "TE 207.19» '. TE 20719" a. 30.3' S X 0.4' W 30,3' S X 0.3' . W� GAS LINE ENDS ...21 O T S T S V V PER PSE AS -BUILT MAP c c c c c c c 55 SS SS HOME TECH 13608 SE 51ST PL BELLEVUE, WA 206 778 2431 r� 32229 �RAD/S7'CQ• IWVAL N O co V/ 0 Z cn Z O Q LLl 0 W N N Z � N UU 2 2 Z ~ N W Z o N H M = r- REVISIONS DATE DESIGN: Y. S. DRAWING: H. H. CHECK Y. S. DATE: NOV 4, 2023 SCALE1 AS SHOWN SHEET; 1 CV2 unnea jates -- ss ss ��� HOUSE #7113 10^ i�Z F Postal Service �214°- B2 ` - - - - - - 20e1h St sw \ �' _ 2a"=cga$_ -----ss�rs�o�74.1C 5T,� ji P.CORNER P.CONER > B4 ' _ _ Q_. __ - 4"-C o Q - . i� 10'-0" �e n� 0"-F\ „ 1 - w a w o w � N TOP 4 - - - S-7W _ y Park 210 Q Edmonds, WA 98026 � coNc ALL 409 408.60 II FF=409.10' I I 3 one,ew o,"s TOP 4 4.0 408.40 5 -FT CONIC N R T�NG WALL,I 1ST FLR: 38.5'X21' (808.5SF) CO •� I ' a f SITE s E va. -2ND FLR ' 9.5XSF� '+BUMP -OUT FL�Q I4..•,• I s ®KuzmasF,shMa,ket J I II ( ) �6I .',: virginiamasonEdmonds -3RD FLR •39.5'X21'+BUMP-OUT I I I s Family Medicine Enter{ y I 4m.34-ROOFLII 7 I '' 1 nkay F Banner Bank© Q I I 3 Clearwater Ca, Wash ,sw azm$w 212 stmssw 21 401.14 I f Me9:cTo � �CONC WALL J 407.14 II 3 otaY TOP 1z.o I II%I FF=407.84' Pa,k 2129 �� CONC WALL I III 1ST FLR: 38.5'X21' (808.5SF) " """I �" ca,MaxQ I I �3� TOP 0.0 I -2ND FLR :39.5'X21'+BUMP-OUT ( I y y (8' SF) I 3 SEAWEED Cannabis 4 -3RD FLR :39.5X21'+BUMP-01JT I . 407.2 (' I VICINITY MAP N.T.S. 1 S. TBACK I I-ROOFLINE I 3 I C � I N N laa7.z 4c7.o I lI II FF=407.84' I 3 11/ 1ST FLR:38.5'X21' (808.5SF) I GENERAL INFO: I -2ND FLR :39.5'X21'+BUMP-OUT / Z I I III I (837 SF) I GAR AGE/RECYCL, 0 o SITE ADDRESS: 7103 210TH ST. SW, EDMONDS, WA 98026 N I �-3RD FLR - 39.5 X21'+BUMP-OUT I TYR. Br I I (837 S I OWNER: HARR CHEN PROPERTIES, LLC a 4°zz 10'-0„ TEL: 206 331 5725 P N FI I I-ROOFLINE S. SETBACK SITE DATA: I 7 LOT AREA: 11,201 SF 4a .z 4o7.b j 1 II FF=407.18' ZONING: EAT PU P, 3-FT PARCEL #: 00566900100601 I 22'_0" II , 1ST FLR:38.5'X21' (808.5SF) a R LESS3IN HEIGHT 0 7/ ASPH LT P VEM 7 I 2ND FLR :39.5'X21'+BUMP-OUT 4 - LEGAL DESCRIPTION: (537 SF) ri� SEATTLE HEIGHTS DIV 4 BLK 001 D-01 - BEG SW COR LOT 6 TH ;. N / I aosle ae I j�-3RD FLR (839,37 �>'+BUMP-OUT I 3 E AUG S LN 30.01FTTO POB TH NWLY TAP 3OFT E OF W LN SD / I� I LOT151.14FT NLY FIRM S LN SO LT TH E 74.10FTM/L TO E LN SD N a°ROOFLINE I - i I LT TH S ALG E LN SD T M/L TO E LN SD LOT TH S AEG E LN I j I ,. SDLOT TO SE COR TH W AEG S LN SD LOT TO POB EXISTING 4oss� 11I FF-406.81' I �' EXISTING BUILDING TO BE DEMOLISHED: y n GRADE� o\ I 1 YEAR BUILT: 1947 �N cb I I I 1ST FLR:38.5'X21' (808.5SF) I o? 3 I II 1I -2ND FLR '(837XSF)+BUMP-OUT 1ST FLOOR: 768 SF I I F. BASEMENT: 732 SF I I 1 11l -3RD FLR • 39.5'X21'+BUMP-OUT 1 CARPORT: 572 SF 1 1 (837 SF) 3 PROPOSED CONSTRUCTION: UTILITY EASEMENo Q I 406.11 I I I -ROOFLINE i 1 -F I 4' CONC. WALKWAY 6 ATTACHED 3-STORY TOWNHOUSES W/ EACH UNIT FLOOR AREAS AF 8105070180 N I I II I 1ST FLOOR: 334 SF, 2-CAR GARAGE:447 SF 406.31 II 3 2ND FLOOR: 837 SF 40s1131 I/ FF=406.5' TRYPFNE a"-F I 3RD FLOOR: 837 SF 1ST FLR:38.5'X21' 808.5SF I I 4' CO C. WALKWAY 0� I22,�Q'li -2ND FLR :3937XS21'+BUMP)OUT i I 1 ,.TREE PROTECTION LOT COVERAGE CALCULATIONS: -3RD FLR :39.5X21'+8UMP-0U7 (45% max.) TREE TO E DRIVE AY 837 � ° -F I W BUILDING FOOTPRINT 6X837SF =5022 SF R01g1FI W BIKE RACK,SEE REM VED, T P. _ 23 - C�406 T3lJICDIG HEIGHT UBR-1/CV4.2 7� h:F( `( 212„_F 3 Q / i LOT COVERAGE 5022.0 SF 11201 SF=44.8% OK 1 CALCULATION BOX FOR DETAILS 1� I � N A L 1 " 2 40s.8 BUILDING HEIGHT CALCULATIONS: O1 I I 3 8.5' 0 0 MF ... 0 y y F2 - - - - - CON 18PAe1 WALKWAY POINT A B C D �N " F3 -IALL PEDESTAL I ELEVATION 406 413.60 41258 406.91 �P.CORNER 619.5' F41 k « AVERAGE 1639.09/4=409.77 Ff FF EXI F.H. TO RETAINED IF T IS CO FIRMED WITHH THE FIRE MA SHAL rn MAX HEIGHT 409.77+25=434.77 CB N z 4\c C. WALKWAY MAX ROOF HEIGHT 409.77+25+5=439.77 w - Iwl w ao 4 ri, `• %': o ', l l aN 4/L3 R ORNER RIM 405.34 f� w `mow. ;�/' ETPIL �i ew AMP DI ClSEESPROJECT E: E (12 N) 402.09 -SD-SD SD S0'L6NE-MADILBO SD .. .. .. 'W' W W IE (12"S) 400.40°- sD_ SD- sD 1 - w E (12"E/W) 400.39�Rz c� SD- SDI S SD- ) I CIVILS FOR FULL CONSTRUCTION PLANS / SDI SDI SD�� SD / irrigation aPrinklin9 CB TYPE1(SOLID LID) I ce 01.40 TYPE'/ �b snap be obtained RIM 408.59 RIM TYPE'405.40 6-N +1-EXI T((TO BE UPGR{��DED)) from Public Works Cross 12"GONG E IE 402.73 / ALL �w WITH 1.5$' PEX PIPE W/TRACER �• Connection 12"GONG W IF 403.30 12"CONC W IE 402.67 / WIRES, 6 UNITS W/ WATER & / Control Specialist - Jeff 12 GONG N IF 403.24 y-- SPRINKLING, AND 1 IRRIGATION METER. Koblyk. Rhona: n I N(PROJECT REFERENCE DATUM)- _ / 4z5-771-0235 or e-1 - 2�tH ST SW eff.koblyk �edmondswa.gov.� ECTO REFER WA-100/SHEET CU6.2 y (E) 6"PVC SEWER1PIPEOW /� \ N (TO BE VERIFIED 8 SUcTBJECT TO INSPECTION) J E D LA V \\\ I 1 101 0 6• 301 20• \ s o \ SS- Ss- SS_ SS_ Sg Ss- SS- SS- ss-I 11 \\ ss- ss- ss-�- SS- sce1.B: 1' 111 lo• \ .•., _. ,_.�. _.... f 1 SS- SS- SS- SS- SS- SS- SS- SS- SSA - THE BUILDING HEIGHT RECTANGLE REVISED, NO AFFECT ❑N ELEVATIONS OTHER REVISIONS IN RESPONSE TO ENGINEERING REVIEW COMMENTS HOME TECH 13608 SE 51ST PL BELLEVUE, WA 206 778 2431 hometechwa@gmaii.com �ewoe easyl��� 32229 �R�/S7'CQ� IWVAL N O CID Z G 0 N W W W 3.1 CO Z :) N Z Z Z p a LJJH M V o REVISIONS DATE �l JAN 25, 2024 MAY 12, 2024 DESIGN: Y. S. DRAWING: H. H. CHECKI Y. S. DATE: JAN 25, 2024 SCALEI AS SHOWN SHEETI 1 SITE 1 Ss ss� 5 ram P.CO NER y I 4os 408.40 rn I /_te---J Sp N N N N / A N W C N A A I / N I EXISTING GRADE � rn N I y y UTILITY EASEMENo AF 8105070180 I SD2 y TYPE 1 CB I I RIM 405.8 0 4" IE (E IN): 404.3' 4" IF (S OUT): 404. REFER TO NOTES 3 6 o � I -rre01\�1 'r ...L.TOWARDS _------- 4 407. AIDED TO DRAIN PROPOSEDCB III I I I I 407.34 407.14 l I I I I I 407.2 I -BUILDING FOOTPRINT 1407.2 407.0 I I I I I o I I I I407.21 I 407.2 407.0 I 22'-0" PH LT P VEM TI I IN 4148 I 406.6 y L= y I dy I I oII I �Iow I I I 4os.11 I I 406.31 I I I 406.31 I �I I I I I I DRIV NAY 406 SD1 CLEANOUT RIM 406' DOWNSPOUT CONNECTION, IE 404.5' FOOTING DRAIN CONNECTION IE 404.5' REFER TO NOTES 2 AND 3. �-_41E41AL IN)-. 403.5' ir, -F DRAINAGE NOTES: LEGEND 1. CONTRACTOR SHALL VERIFY RIM AND ® FOUND MONUMENT AS NOTED P.CORNER INVERT ELEVATIONS AND SHALL NOTIFY SET 24" X 12" REBAR WITH "LS / ENGINEER IF DIFFERENT THAN PLANS. CAP STAMPS 32441" T8 ...: 4 FOUND MAG AND WASHER AS NOTED 2"=L 2. ALL DOWNSPOUT CONNECTIONS SHALL FOUND IRON PIPE OR REBAR AND ® CAP (RBC) AS NOTED 3 BE A MINIMUM OF 18" BELOW FINAL GRADE. 0 WATER METER - WATER VALVE II FIRE HYDRANT � 3. ALL STORM PIPES SHALL BE 4" PVC UTILITY POLE AND HAVE A MINIMUM SLOPE OF 2%, UTILITY POLE WITH LIGHT UNLESS OTHERWISE INDICATED. I 3 1 cuY ANCFOR I ® MAILBOX I 4. INFILTRATION TRENCH SHALL BE 1 a SIGN a PER DOE MANUAL BMP T5.10A.. I � GATE POST PERFORATED PIPES SHALL BE FLAT. � TYPE I CATCH BASIN I REFER TO SHEET SD2. I 3 Q STORM DRAIN MANHOLE I STORM DRAICLEAN OUT ® I 5. PROPOSED WALKWAY SHALL BE GRADED I O SANITARY SEWER MANHOLE a TO DRAIN AWAY FROM BUILDINGS AND o SANITARY SEWER CLEANOUT I TOWARDS VEGETATED AREAS WITH A GRADE - X - FENCE (TYPE NOTED) I 3 I BETWEEN 1-1.5%. G GAS I - SD- STORM DRAIN 6. PROPOSED CATCH BASIN AND SUMP LIDS w WATER 3 SHOULD BE FLUSH WITH FINISHED GRADE. -P - OVERHEAD UTILITIES I I ss SANITARY SEWER I 4� LOCUST (-L) CEDAR (-C) FIR (-F) 7 3 PINE Ell ASPHALT 3 CONCRETE I I I 13 CATCH BASIN (CB) 3 - DIRECTION OF FLOW . CLEANOUT 0 CB SUMP 3 --uav--- UNDERGROUND POWER --u■c-- UNDERGROUND COMM. LINE ® HUNTER PROS-06-PRS30 3 I ❑ TYPE 2 LANDSCAPE I TYPE 3 LANDSCAPE 1 3 1 GREEN STRIP I JJ- REFS TO NOTE 5 FOR WALKWAY SLOPE lYl EB RAMP > 3 CONC. PAVER 2'X2' STEP STONE I� 336'x5'x4' IINFILTRATION TRENCH, o .. �---- -- '• REFER TO NOTE 4. I 406 855 8 0000 a' I rn :•::•: :•:::::• • .•::::`•'•::•::• •::•:• F' : 18"X18"-30" ti �PWI P.GORNER 19.5' 3fALL PEDESTAL N I I N •:•::•:•' ':::: •L:; fF 05I .4 Q EX F.H. TO BE RETAINED I ti N � "40$ 4 L3C30 C�OOCI C6flOC�00-`.,0�0 rn CB -w-wl c IwI�wN I RIM 405.34 I-w i5r Wow .IIF1 W, y T= W wl-tL.L.RAMP IE (12"N) 402.09 SD SD SD SD�NS SID SO w • 1y �% DI w IE (12"S) 400.40 °� sD- S - l w w V w- w IE (12"E/W) 400.39 SUMP W/SOLID LID, coy BOX zcoN SD-sD�SD�SD�sD�SD� PROPOSED RIM 405.9' M SDI -SD UNDERGROUND / / POWER LINE BY 4" IF (N IN): 404.0' / / CB TYPE1(SOLID LID) cB TYPE1 4" IE (E OUT): 403 �' I RIM 408.59 PUD DESIGN I RIM 402.67 / 1ZI.K E IE 402.73 REFER TO NOTES , & 6 P, 12"CONC W IE 403.30 z"caNc w IE aozs7 12"CONC N IF 403.24 I (PROJECT REFERENCE DATUM)- 1 j - - - PROPOSED 2 0TH ST SW BLUE REELEcraREFER UNDERGROUND --J WA-100/SHEET CV5.2 COMMUNICATION I CABLE LINE BY 1 DRAINAGE PLAN ZIPLY FIBER/ � o `\ 10' 0 5' 10' 20' � s ss iS- SS- SS- SSCOMCAST DESIGN- y SS- SS- SS- SS -Is, SS- SS---�- SS- SS- SS- SS- SS- SSCAIR: 1' = 10' S- SS- SS- SS- nn Tvnrnun nnc nn � SS I HARD SURFACE I AREA IPROPOSED BMP I BUILDING FOOTPRINT 4,884 SF FULL INFILTRATION DRIVEWAY 3,133 SF FULL INFILTRATION WALKWAY 855 SF SHEET FLOW APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: BY: CITY ENGINEERING DIVISION SH FINE CONSULTING 13608 SE 51st PI Bellevue, WA 98006 (425)444-9740 k� " tQYpt, 09/25/24 N O co V/ Z O r F W W ,N V^ `T/ r a 2 = Zb O N O ~o V ) r = 1� REVISIONS DATE DESIGN: J.S. DRAWING; K.A.F. CHECKI J.S. DATE: SCALEI SEE PLAN SHEET; VV5.1 TYPE 1 OR 1-L CATCH UNDERDRAIN PIPE I D BASIN W/ SOLID LID PER GUTTER CITY STANDARD DETAIL SD-303 OR SD-304 ROOF Z� ...... . .. .. .. .. .. .. .. .. .. .. ... ...TTRENCH W J) 5 Q o W (MIN) — — — — -- — — J 4 5' (MIN) a INFILTRATION z �10' (MIN) EXTENTS ' — — — — PROPERTY LINE/EASEMENT QF RQ PLAN 4" (MIN) DIA. OBSERVATION WELLS NTS ROOF SPACED 25' APART (MAX), 1 DOWNSPOUT WELL (MIN) PER TRENCH CLEANOUT ILDING 12"fREMOVABLE 4" (MIN) PVC DRAIN PIPE PER WSDOT LEVEL SPEC. 9-05.1(5), MAINTAIN POSITIVE SLOPE PERFORATED PVC UNDERDRAIN PIPE SH—ON PVC TEE PER WSDOT SPEC. 9-05.2(6), LAID LEVEL, SEE NOTE 5 100' (MAX) REFERTOCV5.1 PROFILE GENERAL NOTES: PLASTIC BOX NTS MARKED "DRAIN" 1. REFER TO THE 2022 CITY OF EDMONDS TEST PLUG STORMWATER ADDENDUM FOR SETBACK (CHECKLIST 13) AND INFEASIBILITY REQUIREMENTS. - 6" (MIN) 2. MIN COVER DEPTHS ASSUME NO VEHICULAR - COMPACTED LOADING, DESIGNER TO SPECIFY COVER DEPTHS IF BSERVATION BACKFILL VEHICULAR TRAFFIC ANTICIPATED. VELL, SEE NOTE 3 NOTES: WASHED DRAIN O� ROCK, SEE �C 1. PLACE GEOTEXTILE FABRIC ALONG WALLS AND TOP NOTE 2 3' OF WASHED ROCK. GEOTEXTILE SHALL CONFORM TO 14' _ _ GEOTEXTILEWSDOT SPEC. 9-33.2(1), GEOTEXTILE FOR �JO SEPARATION,NON-WOVEN SEE NOTE 1 O QOO� 2. WASHED DRAINROCK SHALL CONFORM TO WSDOT SPEC. 9-03.12(5), GRAVEL BACKFILL FOR DRYWELLS. 1' (MIN) 3. OBSERVATION WELL SHALL CONFORM TO WSDOT 2' (MIN) � ABOVE SPEC. 9-05.2(6), PERFORATED PVC UNDERDRAIN SEE NOTE 4 7 SEASONAL PIPE. UNCOMPACTED NATIVE E7 HIGH 4. MAXIMUM WIDTH SHALL BE 4 FEET TO MEET MINIMUM MATERIAL, SCARIFY 3" GROUNDWATER REQUIREMENT NO. 5 (SEE EDMONDS STORMWATER (MIN) TABLE OR ADDENDUM). SECTION q HYDRAULICALLY 5. 4 INCH DIA. PERFORATED PIPE FOR 2' TO LESS NTS - RESTRICTIVE THAN 3' WIDE TRENCH. 6 INCH DIA. PERFORATED LAYER PIPE FOR 3'-4' WIDE TRENCH. REVISION DATE TYPICAL ROOF DOWNSPOUT SEPTEMBER 2023 APPROVED FOR CONSTRUCTION CITY OF EDMONDS INFILTRATION TRENCH CITY OF EDMONDS PUBLIC WORKS STANDARD DEPARTMENT DETAIL BATE: Fs t g 9� S D- 6 3 6 APPROVED BY: R. ENGLISH BY: CITY ENGINEERING DIVISION SH FINE CONSULTING 13608 SE 51stPl Bellevue, WA 98006 (425)444-9740 SHENECONSULUNG @GMAIL.COM 5¢W of wasyt��,G h 2N 52183 N IorvnL 05/30/24 (O N O 00 O C Z O LU J LU cn LU M i— o Oy W Z H _O Z 0 N H M Z U� REVISIONS DATE MAY 28, 2024 DESIGN, J.S. DRAWING: K.A.F. CHECK, J.S. DATE, NOV 15, 2023 SCALE, NTS SHEET; CV5.2 Appendix B: Minimum Requirements Page 8 January 2024 EDMONDS STORMWATER ADDENDUM Start Does the project result in 2.000 square feet. or greater. of ne« pLus replaced hard surface area' OR Does the land disturbing actiA it% total -.000 square feet or greater'.' Yes No T D Minimum Requirements No. 1 through 5 apply to the ne« Only �Iimimum Requirement \o. '_ applies to the I and replaced hard surfaces plus the land disturbed. nei% and re Ip aced hard surfaces plus the land disturbed. Next Question Does the project add -5.000 square feet or more of neii plus replaced hard surface area? OR No Convert 0. acres or more of vegetation to la%cn or landscaped areas' OR Concert 2.4 acres or more of native vegetation to pasture'' Yes Is this a Road -related project? all Minimum Requirements (1-9) apple to the ne%i and replaced hard surfaces and the concerted vegetated areas. All Minimum Requirements (1-9) apple to the nev hard surfaces and the converted vegetated areas. -yes-, Does the project add 5.000 square feet or more of a No--► hard surface area? Yes Do the I en hard sufaces add 500 o or more to the exisiting hard surfaces iiithin the project limits^ No additional Requirements apph. Note: the minimum requirement(s) that apply to a project are those described in all the red -framed boxes resulting from using the flow chart. See text on page 7 for more details including an example. Figure 3.1 Flow Chart for Determining Requirements for Development. Applicability of the Minimum Requirements 8 Appendix C: Onsite Stormwater Management BMP Selection Page 9 5/29/24, 7:57 PM S411 BMPs for Landscaping and Lawn / Vegetation Management You are here: 2019 SWMMWW > Volume IV - Source Control BMP Library_ > IV-4 Soil Erosion, Sediment Control, and Landscaping Source Control BMPs > S411 BMPs for Landscaping and Lawn / Vegetation Management S411 BMPs for Landscaping and Lawn / Vegetation Management Description of Pollutant Sources: Landscaping can include grading, soil transfer, vegetation planting, and vegetation removal. Examples include weed control on golf course lawns, access roads, and utility corridors and during landscaping; and residential lawn/plant care. Proper management of vegetation can minimize excess nutrients and pesticides. Pollutant Control Approach: Maintain appropriate vegetation to control erosion and the discharge of stormwater pollutants. Prevent debris contamination of stormwater. Where practicable, grow plant species appropriate for the site, or adjust the soil properties of the site to grow desired plant species. Applicable BMPs: • Install engineered soil/landscape systems to improve the infiltration and regulation of stormwater in landscaped areas. • Select the right plants for the planting location based on proposed use, available maintenance,soil conditions, sun exposure, water availability, height, sight factors, and space available. • Ensure that plants selected for planting are not on the noxious weed list. For example, butterfly bush often gets planted as an ornamental but is actually on the noxious weed list. The Washington State Noxious Weed List can be found at the following webpage: https://www.nwcb.wa.gov/printable-noxious-weed-list • Do not dispose of collected vegetation into waterways or storm sewer systems. • Do not blow vegetation or other debris into the drainage system. • Dispose of collected vegetation such as grass clippings, leaves, sticks by composting or recycling. • Remove, bag, and dispose of class A & B noxious weeds in the garbage immediately. • Do not compost noxious weeds as it may lead to spreading through seed or fragment if the composting process is not hot enough. • Use manual and/or mechanical methods of vegetation removal (pincer -type weeding tools, flame weeders, or hot water weeders as appropriate) rather than applying herbicides, where practical. • Use at least an eight -inch "topsoil' layer with at least 8 percent organic matter to provide a sufficient vegetation -growing medium. o Organic matter is the least water-soluble form of nutrients that can be added to the soil. Composted organic matter generally releases only between 2 and 10 percent of its total nitrogen annually, and this release corresponds closely to the plant growth cycle. Return natural plant debris and mulch to the soil, to continue recycling nutrients indefinitely. • Select the appropriate turfgrass mixture for the climate and soil type. o Certain tall fescues and rye grasses resist insect attack because the symbiotic endophytic fungi found naturally in their tissues repel or kill common leaf and stem -eating lawn insects. https:Hfortress.wa.gov/ecy/ershare/wq/Permits/Flare/20l9SWMMWW/2019SWMMWW.htm#Topics/VolumelV/SoilErosionSedimentControlAndLandsc... 1 /4 5/29/24, 7:57 PM S411 BMPs for Landscaping and Lawn / Vegetation Management ■ The fungus causes no known adverse effects to the host plant or to humans. ■ Tall fescues and rye grasses do not repel root -feeding lawn pests such as Crane Fly larvae. ■ Tall fescues and rye grasses are toxic to ruminants such as cattle and sheep o Endophytic grasses are commercially available; use them in areas such as parks or golf courses where grazing does not occur. o Local agricultural or gardening resources such as Washington State University Extension office can offer advice on which types of grass are best suited to the area and soil type. • Use the following seeding and planting BMPs, or equivalent BMPs, to obtain information on grass mixtures, temporary and permanent seeding procedures, maintenance of a recently planted area, and fertilizer application rates: BMP C120: Temporary and Permanent Seeding, BMP C121: Mulching, BMP C123: Plastic Covering, and BMP C124: Sodding. • Adjusting the soil properties of the subject site can assist in selection of desired plant species. Consult a soil restoration specialist for site -specific conditions. Recommended Additional BMPs: • Conduct mulch -mowing whenever practicable. • Use native plants in landscaping. Native plants do not require extensive fertilizer or pesticide applications. Native plants may also require less watering. • Use mulch or other erosion control measures on soils exposed for more than one week during the dry season (May 1 to September 30) or two days during the rainy season (October 1 to April 30). • Till a topsoil mix or composted organic material into the soil to create a well -mixed transition layer that encourages deeper root systems and drought -resistant plants. • Apply an annual topdressing application of 3/8" compost. Amending existing landscapes and turf systems by increasing the percent organic matter and depth of topsoil can: o Substantially improve the permeability of the soil. o Increase the disease and drought resistance of the vegetation. o Reduces the demand for fertilizers and pesticides. • Disinfect gardening tools after pruning diseased plants to prevent the spread of disease. • Prune trees and shrubs in a manner appropriate for each species. • If specific plants have a high mortality rate, assess the cause and replace with another more appropriate species. • When working around and below mature trees, follow the most current American National Standards Institute (ANSI) ANSI A300 standards (see http://www.tcia.org/TCIA/BUSINESS/ANSI A300 Standards /TCIA/BUSINESS/A300 Standards/A300 Standards.aspx? hkey=202ff566-4364-4686-b7c1-2a365af59669) and International Society of Arboriculture BMPs to the extent practicable (e.g., take care to minimize any damage to tree roots and avoid compaction of soil). • Monitor tree support systems (stakes, guys, etc.). o Repair and adjust as needed to provide support and prevent tree damage. https:Hfortress.wa.gov/ecy/ershare/wq/Permits/Flare/20l9SWMMWW/2019SWMMWW.htm#Topics/VolumelV/SoilErosionSedimentControlAndLandsc... 2/4 5/29/24, 7:57 PM S411 BMPs for Landscaping and Lawn / Vegetation Management o Remove tree supports after one growing season or maximum of 1 year. o Backfill stake holes after removal. • When continued, regular pruning (more than one time during the growing season) is required to maintain visual sight lines for safety or clearance along a walk or drive, consider relocating the plant to a more appropriate location. • Make reasonable attempts to remove and dispose of class C noxious weeds. • Re -seed bare turf areas until the vegetation fully covers the ground surface. • Watch for and respond to new occurrences of especially aggressive weeds such as Himalayan blackberry, Japanese knotweed, morning glory, English ivy, and reed canary grass to avoid invasions. • Plant and protect trees per BMP T5.16: Tree Retention and Tree Planting. • Aerate lawns regularly in areas of heavy use where the soil tends to become compacted. Conduct aeration while the grasses in the lawn are growing most vigorously. Remove layers of thatch greater than 3/4-inch deep. • Set the mowing height at the highest acceptable level and mow at times and intervals designed to minimize stress on the turf. Generally mowing only 1/3 of the grass blade height will prevent stressing the turf. o Mowing is a stress -creating activity for turfgrass. Grass decreases its productivity when mowed too short and there is less growth of roots and rhizomes. The turf becomes less tolerant of environmental stresses, more disease prone and more reliant on outside means such as pesticides, fertilizers, and irrigation to remain healthy. Additional BMP Information: • King County's Best Management Practices for Golf Course Development and Operation ,(King County, 1993) has additional BMPs for Turfgrass Maintenance and Operation. • King County, Seattle Public Utilities, and the Saving Water Partnership have created the following natural lawn and garden care resources that include guidance on building healthy soil with compost and mulch, selecting appropriate plants, watering, using alternatives to pesticides, and implementing natural lawn care techniques. ■ Natural Yard Care -Five steps to make your piece of the planet a healthier place to live .(King County and SPU, 2008) ■ The Natural Lawn & Garden Series: Smart Watering,(Saving Water Partnership, 2006) ■ Natural Lawn Care for Western Washington .(Saving Water Partnership, 2007) ■ The Natural Lawn & Garden Series: Growing Healthy Soil; Choosing the Right Plants; and Natural Pest, Weed and Disease Control (Saving Water Partnership, 2012) • The International Society of Arboriculture (ISA) is a group that promotes the professional practice of arboriculture and fosters a greater worldwide awareness of the benefits of trees through research, technology, and education. ISA standards used for managing trees, shrubs, and other woody plants are the American National Standards Institute (ANSI) A300 standards. The ANSI A300 standards are voluntary industry consensus standards developed by the Tree Care Industry Association (TCIA) and written by the Accredited Standards Committee (ASC). The ANSI standards can be found on the ISA website: www.isa-arbor.com/education/publications/index.aspx https:Hfortress.wa.gov/ecy/ershare/wq/Permits/Flare/2019SWMMWW/2019SWMMWW.htm#Topics/VolumeIV/SoilErosionSedimentControlAndLandsc... 3/4 5/29/24, 7:57 PM S411 BMPs for Landscaping and Lawn / Vegetation Management • Washington State University's Gardening in Washington State website at http-.//gardening.wsu.edu contains Washington State specific information about vegetation management based on the type of landscape. • See the Pacific Northwest Plant Disease Management Handbook,(Pscheidt and Ocamb, 2016) for information on disease recognition and for additional resources. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 https:Hfortress.wa.gov/ecy/ershare/wq/Permits/Flare/20l9SWMMWW/2019SWMMWW.htm#Topics/VolumelV/SoilErosionSedimentControlAndLandsc... 4/4 You are here: 2019 SWMMWW > Volume V - Runoff Treatment, Flow Control, and LID BMP Library_ > V-11 Miscellaneous LID BMPs > BMP T5.13: Post -Construction Soil Quality and Depth BMP T5.13: Post -Construction Soil Quality and Depth Purpose and Definition Naturally occurring (undisturbed) soil and vegetation provide important stormwater functions including: water infiltration; nutrient, sediment, and pollutant adsorption; sediment and pollutant biofiltration; water interflow storage and transmission; and pollutant decomposition. These functions are largely lost when development strips away native soil and vegetation and replaces it with minimal topsoil and sod. Not only are these important stormwater functions lost, but such landscapes themselves become pollution generating pervious surfaces due to increased use of pesticides, fertilizers and other landscaping and household/industrial chemicals, the concentration of pet wastes, and pollutants that accompany roadside litter. Establishing soil quality and depth regains greater stormwater functions in the post development landscape, provides increased treatment of pollutants and sediments that result from development and habitation, and minimizes the need for some landscaping chemicals, thus reducing pollution through prevention. Applications and Limitations Establishing a minimum soil quality and depth is not the same as preservation of naturally occurring soil and vegetation. However, establishing a minimum soil quality and depth will provide improved on -site management of stormwater flow and water quality. Soil organic matter can be attained through numerous materials such as compost, composted woody material, biosolids, and forest product residuals. It is important that the materials used to meet this BMP be appropriate and beneficial to the plant cover to be established. Likewise, it is important that imported topsoils improve soil conditions and do not have an excessive percent of clay fines. This BMP can be considered infeasible on till soil slopes greater than 33 percent. Design Guidelines Soil Retention Retain, in an undisturbed state, the duff layer and native topsoil to the maximum extent practicable. In any areas requiring grading, remove and stockpile the duff layer and topsoil on site in a designated, controlled area, not adjacent to public resources and critical areas, to be reapplied to other portions of the site where feasible. Soil Quality_ All areas subject to clearing and grading that have not been covered by impervious surface, incorporated into a drainage facility or engineered as structural fill or slope shall, at project completion, demonstrate the following: 1. A topsoil layer with a minimum organic matter content of 10% dry weight in planting beds, and 5% organic matter content in turf areas, and a pH from 6.0 to 8.0 or matching the pH of the undisturbed soil. The topsoil layer shall have a minimum depth of eight inches except where tree roots limit the depth of incorporation of amendments needed to meet the criteria. Subsoils below the topsoil layer should be scarified at least 4 inches with some incorporation of the upper material to avoid stratified layers, where feasible. 2. Mulch planting beds with 2 inches of organic material. 3. Use compost and other materials that meet the following organic content requirements: a. The organic content for "pre -approved" amendment rates can be met only using compost meeting the compost specification for BMP T7.30: Bioretention, with the exception that the compost may have up to 35% biosolids or manure. The compost must also have an organic matter content of 40% to 65%, and a carbon to nitrogen ratio below 25:1. The carbon to nitrogen ratio may be as high as 35:1 for plantings composed entirely of plants native to the Puget Sound Lowlands region. b. Calculated amendment rates may be met through use of composted material meeting (a.) above; or other organic materials amended to meet the carbon to nitrogen ratio requirements, and not exceeding the contaminant limits identified in Table 220-13, Testing Parameters, in WAC 173-350-220. The resulting soil should be conducive to the type of vegetation to be established. Implementation Options The soil quality design guidelines listed above can be met by using one of the methods listed below: 1. Leave undisturbed native vegetation and soil, and protect from compaction during construction. 2. Amend existing site topsoil or subsoil either at default "pre -approved" rates, or at custom calculated rates based on tests of the soil and amendment. 3. Stockpile existing topsoil during grading, and replace it prior to planting. Stockpiled topsoil must also be amended if needed to meet the organic matter or depth requirements, either at a default "pre - approved" rate or at a custom calculated rate. 4. Import topsoil mix of sufficient organic content and depth to meet the requirements. More than one method may be used on different portions of the same site. Soil that already meets the depth and organic matter quality standards, and is not compacted, does not need to be amended. Planning/Permittinglinspection/Verification Guidelines & Procedures Local governments are encouraged to adopt guidelines and procedures similar to those recommended in Building Soil: Guidelines and Resources for Implementing Soil Quality and Depth BMP T5.13 in WDOE Stormwater Management Manual for Western Washington (Stenn et al., 2016). Maintenance • Establish soil quality and depth toward the end of construction and once established, protect from compaction, such as from large machinery use, and from erosion. • Plant vegetation and mulch the amended soil area after installation. • Leave plant debris or its equivalent on the soil surface to replenish organic matter. • Reduce and adjust, where possible, the use of irrigation, fertilizers, herbicides and pesticides, rather than continuing to implement formerly established practices. Runoff Model Representation All areas meeting the soil quality and depth design criteria may be entered into approved runoff models as "Pasture" rather than "Lawn/Landscaping". 4i pdf download Figure V-11.1: Planting Bed Cross -Section Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 Mulcr Loose soil with visible dark organic matter Loose or fractured subsoil Reprinted from Guidelines and Resources For Implementing Soil Quality and Depth BMP T5.13 in WDOE Stormwater Management Manual for Western Washington, 2010, Washington Organic Recycling Council vadh! q1NOWS DEPARTMENT OF ECOLOGY Planting Bed Cross -Section h[01110lo�Y41_100 Revised June 2016 Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, limitation of liability, and disclaimer. State of Washington You are here: 2019 SWMMWW > Volume V - Runoff Treatment, Flow Control, and LID BMP Library_ > V-4 Roof Downspout BMPs > BMP T5.10A: Downspout Full Infiltration BMP T5.10A: Downspout Full Infiltration Downspout full infiltration systems are trench or drywell designs intended only for use in infiltrating runoff from roof downspout drains. They are not designed to directly infiltrate runoff from pollutant -generating impervious surfaces. Roof surfaces that comply with this BMP are considered to be "fully infiltrated" (i.e., zero percent effective imperviousness). Procedure for Evaluating Feasibility 1. Have one of the following prepare a soils report to determine if soils suitable for infiltration are present on the site: o A professional soil scientist certified by the Soil Science Society of America (or an equivalent national program) o A locally licensed on -site sewage designer d A suitably trained person working under the supervision of a professional engineer, geologist, hydrogeologist, or engineering geologist registered in the State of Washington. The report shall reference a sufficient number of soils logs to establish the type and limits of soils on the project site. The report should at a minimum identify the limits of any outwash type soils (i.e., those meeting USDA soil texture classes ranging from coarse sand and cobbles to medium sand) versus other soil types and include an inventory of topsoil depth. 2. Complete additional site -specific testing on lots or sites containing outwash (coarse sand and cobbles to medium sand) and loam type soils. Individual lot or site tests must consist of at least one soils log at the location of the infiltration system, a minimum of 4 feet in depth from the proposed grade and at least 1 foot below the expected bottom elevation of the infiltration trench or dry well. Identify the NRCS series of the soil and the USDA textural class of the soil horizon through the depth of the log, and note any evidence of high ground water level, such as mottling. 3. Downspout full infiltration is considered feasible on lots or sites that meet all of the following: d 3 feet or more of permeable soil from the proposed final grade to the seasonal high ground water table. o At least 1-foot of clearance from the expected bottom elevation of the infiltration trench or dry well to the seasonal high ground water table. o The downspout full infiltration system can be designed to meet the minimum design criteria specified below. Setbacks Local governments may require specific setbacks in sites with slopes over 40%, land slide areas, open water features, springs, wells, and septic tank drain fields. Adequate room for maintenance access and equipment should also be considered. Examples of setbacks commonly used include the following: 1. All infiltration systems should be at least 10 feet from any structure, property line, or sensitive area (except slopes over 40%). 2. All infiltration systems must be at least 50 feet from the top of any slope over 40%. This setback may be reduced to 15 feet based on a geotechnical evaluation, but in no instances may it be less than the buffer width. 3. For sites with septic systems, infiltration systems must be downgradient of the drainfield unless the site topography clearly prohibits subsurface flows from intersecting the drainfield. Design Criteria Infiltration Trenches Figure V-4.1: Typical Downspout Infiltration Trench shows a typical downspout infiltration trench system, and Figure V-4.2: Alternative Downspout Infiltration Trench System for Coarse Sand and Gravel presents an alternative infiltration trench system for sites with coarse sand and cobble soils. These systems are designed as specified below. 1. The following minimum lengths (linear feet) per 1,000 square feet of roof area based on soil type may be used for sizing downspout infiltration trenches: o Coarse sands and cobbles: 20 LF d Medium sand: 30 LF o Fine sand, loamy sand: 75 LF o Sandy loam: 125 LF o Loam: 190 LF 2. Silt and clay type soils have a saturated hydraulic conductivity that is too small for adequate infiltration and are infeasible for downspout infiltration trenches. 3. The maximum length of the trench shall not exceed 100 feet from the inlet sump. 4. The minimum spacing between trench centerlines shall be 6 feet. 5. Filter fabric shall be placed over the drain rock as shown on Figure V-4.1: Typical Downspout Infiltration Trench prior to backfilling. 6. Infiltration trenches may be placed in fill material if: o the fill is placed and compacted under the direct supervision of a geotechnical engineer or professional civil engineer with geotechnical expertise, and o the measured infiltration rate is at least 8 inches per hour. Trench length in fill must be 60 linear feet per 1,000 square feet of roof area. Infiltration rates can be tested using the methods described in V-5.4 Determining the Design Infiltration Rate of the Native Soils. 7. Infiltration trenches should not be built on slopes steeper than 25% (4:1). A geotechnical analysis and report may be required on slopes over 15%, or if the proposed trench is located within 200 feet of the top of a slope steeper than 40%, or in a landslide hazard area. 8. Infiltration trenches may be located under pavement if a small yard drain or catch basin with grate cover is placed at the end of the trench pipe such that overflow would occur out of the catch basin at an elevation at least one foot below that of the pavement, and in a location which can accommodate the overflow without creating a significant adverse impact to downhill properties or drainage systems. This is intended to prevent saturation of the pavement in the event of system failure. Figure V-4.1: Typical Downspout Infiltration Trench pdf download Figure V-4.2: Alternative Downspout Infiltration Trench System for Coarse Sand and Gravel pdf download Infiltration Dr wells Figure V-4.3: Typical Downspout Infiltration Drywell shows a typical downspout infiltration drywell system. These systems are designed as specified below. 1. Drywell bottoms must be a minimum of 1 foot above the seasonal high ground water level or impermeable soil layers. 2. When located in course sands and cobbles, drywells must contain a volume of gravel equal to or greater than 60 cubic feet per 1000 square feet of impervious surface served. When located in medium sands, drywells must contain at least 90 cubic feet of gravel per 1,000 square feet of impervious surface served. 3. Drywells must be at least 48 inches in diameter (minimum) and deep enough to contain the gravel amounts specified above for the soil type and impervious surface served. 4. Filter fabric (geotextile) must be placed on top of the drain rock and on drywell sides prior to backfilling. 5. Spacing between drywells must be a minimum of 10 feet. 6. Downspout infiltration drywells must not be built on slopes greater than 25% (4:1). Drywells may not be placed on or above a landslide hazard area or on slopes greater than 15% without evaluation by a licensed engineer in the state of Washington with geotechnical expertise or a licensed geologist, hydrogeologist, or engineering geologist, and with jurisdiction approval. Figure V-4.3: Typical Downspout Infiltration Drywell pdf download Runoff Model Representation Roof areas served by downspouts that drain to infiltration dry wells or infiltration trenches that are sized in accordance with the guidance in this BMP do not have to be entered into the runoff model. They are presumed to fully infiltrate the roof runoff. Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 Plan Vie i I-- - - - - - - - - - - - - - - � infiltration trench roof drain overflow Profile View 4" rigid or 6" flexible splash block A perforated pipe CB sump w/solid lid 6�� _,,, 1=III„ III=111�1� — ,,III,,III,,III 111�1�111= — — — — — — — — — — — — 6" 12" washed rock 1 %z " - %4" 1' min 1' min Afine mesh screen varies 10' min. 5' min. Section A -A filter fabric compacted backfill 6" 24" 4" rigid or 6" flexible perforated pipe 12" i gip —_ washed rock 1 %" - Y4" Wf1=19=4=111W' 24" NOT TO SCALE Typical Downspout Infiltration Trench Revised June 2016 DEPARTMENT OF ECOLOGYPlease see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, State of Washington limitation of liability, and disclaimer. 5/29/24, 9:01 PM BMP T5.12: Sheet Flow Dispersion You are here: 2019 SWMMWW > Volume V - Runoff Treatment, Flow Control, and LID BMP Library- > V-3 Dispersion BMPs > BMP T5.12: Sheet Flow Dispersion BMP T5.12: Sheet Flow Dispersion Purpose and Definition Sheet flow dispersion is the simplest method of runoff control. This BMP can be used for any impervious or pervious surface that is graded to avoid concentrating flows. Because flows are already dispersed as they leave the surface, they need only traverse a narrow band of adjacent vegetation for effective on -site stormwater management. Applications and Limitations Use this BMP for flat or moderately sloping (< 15% slope) surfaces such as driveways, sports courts, patios, roofs without gutters, lawns, pastures; or any situation where concentration of flows can be avoided. Design Guidelines • See Figure V-3.2: Sheet Flow Dispersion for Driveways for details for driveways. • See BMP T5.10B: Downspout Dispersion Systems for dispersion trench design criteria. • Provide a 2-foot-wide transition zone to discourage channeling between the edge of the impervious surface (or building eaves) and the downslope vegetation. This transition zone may consist of an extension of subgrade material (crushed rock), modular pavement, drain rock, or other material acceptable to the Local Plan Approval Authority. • Provide a 10-foot-wide vegetated buffer for up to 20 feet of width of paved or impervious surface. Provide an additional 10 feet of vegetated buffer width for each additional 20 feet of impervious surface width or fraction thereof. For example, if a driveway is 30 feet wide and 60 feet long provide a 20-foot wide by 60-foot long vegetated buffer, with a 2-foot by 60-foot transition zone. • The design must not result in erosion or flooding of downstream properties. • Runoff discharge toward landslide hazard areas must be evaluated by a geotechnical engineer or a qualified geologist. Do not allow sheet flow on or above slopes greater than 20%, or above erosion hazard areas, without evaluation by a geotechnical engineer or qualified geologist and approval by the Local Plan Approval Authority. • For sites with septic systems, the discharge area must be ten feet downgradient of the drainfield primary and reserve areas (WAC 246-272A-0210). A Local Plan Approval Authority may waive this requirement if site topography clearly prohibits flows from intersecting the drainfield. https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/20l9SWMMWW/2019SWMMWW.htm#Topics/VolumeV/DispersionBMPs/BMPt5l2.htm 1/2 5/29/24, 9:01 PM BMP T5.12: Sheet Flow Dispersion Runoff Model Representation Where this BMP is used to disperse impervious area runoff into an undisturbed native landscape area or an area that meets BMP T5.13: Post -Construction Soil Quality and Depth, the impervious area should be modeled as a lateral flow impervious area. Do this in WWHM on the Mitigated Scenario screen by connecting the lateral flow impervious area element (representing the area that is dispersed) to the lawn/landscape lateral flow soil basin element (representing the area that will be used for dispersion). pdf download Figure V-3.2: Sheet Flow Dispersion for Driveways Washington State Department of Ecology 2019 Stormwater Management Manual for Western Washington (2019 SWMMWW) Publication No.19-10-021 https://fortress.wa.gov/ecy/ershare/wq/Permits/Flare/20l9SWMMWW/2019SWMMWW.htm#Topics/VolumeV/DispersionBMPs/BMPt5l2.htm 2/2 Appendix D: Infiltration Testing and Geotechnical Report Page 10 NELSON GEOTECHNICAL ASSOCIATES. INC. October 16, 2023 Mr. BK Chen VIA Email:.bkchen@gmail.com Stormwater Infiltration Letter (2"d Revision) — UPDATED Chen 210th Street SW Residential Development Infiltration 7103 — 210th Street SW Edmonds, Washington NGA File No. 1209720 17311-135" Ave. N.E. Suite A-500 Woodinville, WA 98072 (425) 486-1669 www.nelsongeotech.com Dear Mr. Chen: This letter documents our explorations and provides our opinions and recommendations for the feasibility of stormwater infiltration for the proposed townhome residential development project located at 7103 — 210th Street SW in Edmonds, Washington, as shown on the Vicinity Map in Figure 1. 1>; 1 1:Z6111101Ii[9LJ The site is currently occupied by a single-family residence within the central portion of the property surrounded by grass -covered yard areas and few scattered young to mature trees. Topography within the site is generally level to gently sloping from north to south. We understand the proposed development will consist of removing the existing site structure and constructing several townhome residence structures within the site. For use in preparing this letter, we have been provided with an untitled and undated preliminary site plan showing the existing and proposed site layout. We understand that stormwater generated from the proposed development may be directed to onsite infiltration systems, if feasible. We have been requested to evaluate the infiltration capacity of the site soils within the property. The City of Edmonds utilizes the 2019 Department of Ecology (DOE) Stormwater Management in Western Washington Manual (2019 SWMMWW) to determine the design of infiltration or detention facilities. According to this manual, long-term design infiltration rates for this site are to be determined by performing on -site infiltration testing consisting of the Small Pilot Infiltration Test (PIT). Stormwater Infiltration Letter (2"d Revision) — UPDATED NGA File No. 1209720 Chen 2101h Street SW Townhome Residential Development Infiltration October 16, 2023 Edmonds, Washington Page 2 SCOPE The purpose of this study is to explore and characterize the subsurface conditions within the site and to provide opinions and recommendations for stormwater infiltration. Specifically, our scope of services included the following: 1. Review available soil and geologic maps of the area. 2. Explore the subsurface soil and groundwater conditions within the site with trackhoe excavated test pits. Trackhoe was subcontracted by NGA. 3. Perform grain -size sieve analysis on selected soil samples, as needed. 4. Provide long-term design infiltration rates based on one on -site small-scale Pilot Infiltration Tests (PIT) per the 2019 SWMMWW. Location and depth of tests to be determined by civil engineer. Water for the test to be secured by client. 5. Provide recommendations for infiltration system installation. 6. Document the results of our findings, conclusions, and recommendations in a written geotechnical letter. SITE CONDITIONS Surface Conditions The property consists of a roughly rectangular -shaped parcel covering approximately 0.26 acres. The site is currently occupied by a single-family residence within the central portion of the property surrounded by grass -covered yard areas and few scattered young to mature trees. Topography within the site is generally level to gently sloping from north to south. We did not observe any surface water within the site on our visit on October 9, 2020. Subsurface Conditions: The geologic units for this area are shown on the Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangles, Washington, by J. P. Minard (U.S.G.S., 1983). The site is mapped as Qva (Advance Outwash deposits), with Qvt (glacial till) nearby. Texture and structure vary from place to place but Advance Outwash generally is composed of moderate- to well -sorted, stratified, light gray to tan medium to coarse sand and pebbly sand containing minor amounts of fine sandy silt. Vashon till typically consists of a concrete -like mixture of relatively equal parts of silt, sand, and gravel. In our explorations, we encountered soils primarily consisting of fine to medium sand with varying amounts of gravel and silt, which we interpreted to be consistent with the description of the outwash deposits mapped in this area. NELSON GEOTECHNICAL ASSOCIATES, INC. Stormwater Infiltration Letter (2"d Revision) — UPDATED NGA File No. 1209720 Chen 2101h Street SW Townhome Residential Development Infiltration October 16, 2023 Edmonds, Washington Page 3 Explorations: The subsurface conditions within the site were explored on October 9, 2020 by excavating three test pit explorations with a mini -excavator as shown in Plate 1 below. The approximate locations of our explorations are shown on the Site Plan in Figure 2. A geologist from NGA was present during the explorations, examined the soils and geologic conditions encountered, obtained samples of the different soil types, and maintained logs of the explorations. Plate 1: Excavator equipment utilized to dig explorations. Shown digging Test Pit 1 located to the west of the existing structure and looking north. The soils were visually classified in general accordance with the Unified Soil Classification System, presented in Figure 3. The logs of our explorations are attached to this letter and are presented in Figure 4. We present a brief summary of the subsurface conditions in the following paragraph. For a detailed description of the subsurface conditions, the exploration logs should be reviewed. At the surface of Test Pits 1 and 2, and Infiltration Pit 1, we generally encountered approximately 1.0 feet of surficial topsoil. Underlying the surficial topsoil in Test Pit 1, we encountered approximately 2.0 feet of dark brown silty fine to medium sand with gravel and organics along with a buried topsoil layer that we interpreted as undocumented fill soil. Below the undocumented fill soils in Test Pit 1 and the surficial topsoil in Test Pit 2 and Infiltration Pit 1, we encountered medium dense to dense, brown gray fine to medium sand with varying amounts of sand, gravel and roots that we interpreted as native advance outwash deposits. All of our test pit explorations were terminated within the native advance outwash deposits at depths in the range of 7.0 to 9.5 feet below the existing ground surface. Soil conditions in Test Pit 1 are shown in Plate 2 below. NELSON GEOTECHNICAL ASSOCIATES, INC. Stormwater Infiltration Letter (2"d Revision) — UPDATED Chen 2101h Street SW Townhome Residential Development Infiltration Edmonds, Washington NGA File No. 1209720 October 16, 2023 Page 4 Plate 2: Test Pit 1 soil conditions. Surficial undocumented fill soils underlain by native advance outwash deposits extending to the depths explored. Hydrogeologic Conditions We did not encounter groundwater seepage or observe any indications of groundwater seepage in any of our explorations completed within the site. If groundwater seepage is encountered during construction, we would interpret this water to be perched groundwater. It is our opinion that the potential for perched groundwater within the upper advance outwash soils is low due to the relatively granular nature of the native advance outwash soils underlying the site. Perched water occurs when surface water infiltrates through less dense, more permeable soils and accumulates on top of underlying, less permeable soils. Perched water tends to vary spatially and is dependent upon the amount of precipitation. We would expect the amount of perched water to decrease during drier times of the year and increase during wetter periods. Perched water does not represent a regional groundwater "table" within the upper soil horizons. We anticipate that the seasonal high groundwater table within the area is located at a greater depth below the site and should not adversely impact the proposed infiltration systems within the site. NELSON GEOTECHNICAL ASSOCIATES, INC. Stormwater Infiltration Letter (2"d Revision) — UPDATED NGA File No. 1209720 Chen 2101h Street SW Townhome Residential Development Infiltration October 16, 2023 Edmonds, Washington Page 5 Stormwater Infiltration The subsurface soils generally consisted of topsoil and/or fill underlain by fine- to medium- grained sand with varying amounts of silt and gravel to the depths explored within the proposed infiltration areas. We conducted on -site infiltration testing in accordance with the 2019 SWMMWW, to determine the long term design infiltration rate of the site soils. On -site testing consisted of a Small Pilot Infiltration Test (Small PIT) to determine the long-term design infiltration rates. We conducted a Small PIT within Infiltration Pit 1, located as shown on the attached Site Plan in Figure 2 and in Plate 3 below. The test was conducted within a pit that measured 6.0-feet long by 4.5-feet wide by 5.0-feet deep. Due to the granular nature of the site soils and the maximum capacity of the on -site water source, we were only able to maintain approximately 8.5-inches of standing water within the hole instead of the recommended 12-inches. This level was maintained within the PIT for approximately 6 hours for the pre soak period of the test. At this time, the water flow rate into the hole was monitored with a Great Plains Industries (GPI) TM 075 water flow meter. Plate 3: Infiltration PIT 1 location looking southeast. NELSON GEOTECHNICAL ASSOCIATES, INC. Stormwater Infiltration Letter (2"d Revision) — UPDATED NGA File No. 1209720 Chen 2101h Street SW Townhome Residential Development Infiltration October 16, 2023 Edmonds, Washington Page 6 After the 6-hour soaking period was completed, the water level was maintained at approximately 8.5- inches for one hour for the steady-state period. The flow rate for Infiltration Pit 1 stabilized at 2.50 gallons per minute (150 gallons per hour), which equates to an approximate infiltration rate of 8.95 inches per hour. The water was shut off after the steady-state period and monitored at least every 15 minutes. After 60 minutes, the water level within the pit dropped approximately 8.0 inches, resulting in an infiltration rate of 8.0 inches per hour. At the conclusion of the testing, Infiltration PIT 1 was excavated an additional two feet to a total depth of 7.0 feet below the existing ground surface and no indications of groundwater seepage and/or impermeable zones were observed. CONCLUSIONS It is our opinion that the subsurface soils within the site are suitable for traditional stormwater infiltration. In accordance with the Table 3.5 of the 2019 SWMMWW, correction factors of 0.8, 0.5, and 0.9 for site variability and number of locations tested (CFv), testing method (CFt), and degree of influent control to prevent siltation and bio-buildup (CFm), respectively were applied to the field measured infiltration rate of 8.0 inches per hour, selected from the falling -head portion of the testing. A total correction factor of 0.36 was applied to the measured field infiltration rate obtained from the falling head portion of the test to determine the long-term design infiltration rate. Using the above correction factor, we calculated a long-term design infiltration rate of approximately 2.88 inches per hour. The base of the infiltration systems should terminate within the native glacial outwash soils encountered at depth. The stormwater infiltration systems should be designed and maintained in accordance with 2019 SWMMWW. The stormwater manual recommends a minimum five-foot separation between the base of an infiltration system and any underlying bedrock, impermeable horizon, or groundwater. We did not observe any indications of or encounter groundwater and/or impermeable layers within our explorations to a depth of up to 9.5 feet below the existing ground surface within the site. We anticipate that the seasonal high groundwater table within the area is located at a greater depth below the site and should not adversely impact the proposed infiltration systems within the site. We recommend that any infiltration systems be placed as to not negatively impact any proposed or existing nearby structures and also meet all required setbacks from existing property lines, structures, and sensitive areas as discussed in the drainage manual. In general, infiltration systems should not be located within proposed fill areas within the site associated with site grading or retaining wall backfill as such condition could lead to failures of the placed fills and/or retaining structures. We should be retained to evaluate the infiltration system design and installation during construction, if necessary. NELSON GEOTECHNICAL ASSOCIATES, INC. Stormwater Infiltration Letter (2"d Revision) — UPDATED NGA File No. 1209720 Chen 2101h Street SW Townhome Residential Development Infiltration October 16, 2023 Edmonds, Washington Page 7 USE OF THIS LETTER This letter was prepared for Mr. BK Chen and his agents, for use in planning and budgeting the above - referenced project only. Our services included an evaluation of the infiltration capability of the site soils at specific locations and should not be considered as an in-depth geotechnical study of the site or an evaluation of the overall site stability. This letter may be used for bidding and estimating purposes, but our letter, conclusions, and interpretations should not be construed as a warranty of the subsurface conditions. The subsurface conditions between explorations may vary. A contingency for varying conditions should be incorporated into the project plans. We recommend that NGA be retained to review the design and provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork activities comply with contract plans and specifications. We should be contacted a minimum of one week prior to construction activities and could attend pre -construction meetings if requested. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering practices in effect in this area at the time this letter was prepared. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are a means to identify and reduce the inherent risks to the owner. • • • NELSON GEOTECHNICAL ASSOCIATES, INC. Stormwater Infiltration Letter (2"d Revision) — UPDATED NGA File No. 1209720 Chen 210th Street SW Townhome Residential Development Infiltration October 16, 2023 Edmonds, Washington Page 8 We appreciate the opportunity to provide service to you on this project. If you have any questions or require further information, please call. Sincerely, NELSON GEOTECHNICAL ASSOCIATES, INC. LEE S. BELLAH Lee S. Bellah, LG Project Geologist .2023 Khaled M. Shawish, PE Principal LSB:KMS:dy Four Figures Attached NELSON GEOTECHNICAL ASSOCIATES, INC. VICINITY MAP N Not to Scale 204th St SW zoau SW Smart Foodservice Q 2041h St SW Warehouse Stores s � _ , s ' College Place Doug Hyundai 206thStSW Middle School _ D © El Antojo I Lynnwood a s � Project Walgreens Drug store 208th St SW r 208th St sw Site A T T L E HEIGHTS 208u, St sw P Pinewood Square 0 a Apartments > f � < W 21 Dth , 1 s'l! Snohomish County PUD Q > Lynnwood Office ` Burger King © se O sw Edmonds-Woodway © 212th St SW 212th St SW 212th St SW 212th St SW 2129 High School 01 a p Park 212 Q a > CarMax ` ® <' Q 30 Used car dealer g Southwest F'- 6 & Transf McDonald's 15 Swedish Edmonds Campus g E 216th S! SW / 2161h St SW Z Pr6mera Blue Cross Q : 0 QUpstaging Seattle 75 �4 0 Q � t e1i s. sv / � 21E1r s, "AI t ® WinCo Foods N Edmonds, WA N U Project Number Chen 210th St SW NELSON GEOTECHNICAL No. Date Revision By I CK N 1209720 Residential Development NGA ASSOCIATES, INC. 1 10/23/20 Original DPN LSB Infiltration GEOTECHNICAL ENGINEERS & GEOLOGISTS 6 E Figure 1 g Vicinity Map Woodinvillel�ce Wenatchee Office Woodi5ihe,WA9,A-500 105Pal,W St Wootllnville, WA 980]2 Wenatchee, WA 96801 9 (425) 486-16691 Fax:481-2510 www. ne,ongeotech—, (509) 665-76961 Fax: 665-7692 5 Existing Residence FF=413' --1ST LEVEL: 38.75'X21't (814SF) 2ND LEVEL: 39.75'X21'± (835S Ii -3RD LEVEL: 40.75'X21't (856SF) l� FF=411.5' i 1ST LEVEL: 38.75'X21't (814SF) I 2ND LEVEL: 39.75'X21't (835SF) i� 3RD LEVEL: 40.75'X21't (856SF) 410 FF=409.5' 1ST LEVEL: 38-75'X21't (814SF) r 2ND LEVEL: 39.75'X21't (835SF) TP-1 3RD LEVEL: 40.75'X21't (856SF) I l i 408 1ST LEVEL: 38.75'X21't (814SF) J Proposed Townhome 2ND LEVEL: 39.75'X21't (835SF) m i 3RD EVEL: 40.75'X21't (typ) il- m F 406 _ FF=407.0' 111't (35SF)12' 0 7— N SB-2 3RD LEVEL: 40.75'X21't (856SF)TLV1S �Tll LEGEND I FF=406.5' 1ST LEVEL: 38.75'X21't (814SF) 2ND LEVEL: 39.75'X21't (835SF) 3RD LEVEL: 40.75'X21't (856SF) 25'-0" INF-1 TP-2 DRIVEWAY PAVEMENT: 41 L 74'-6" `a Property line la INF-1 v Number and approximate 0 20 40 location of infiltration test pit TP-1 Number and approximate Scale: 1 inch = 20 feet Q location of test pit Reference: Site Plan based on an undated, untitled site plan. z Project Number Chen 210th St SW NELSON GEOTECHNICAL No. Date Revision By LL CK a 1209720 Residential Development Infiltration N G A ASSOCIATES, INC. GEOTECHNICAL ENGINEERS & GEOLOGISTS 1 10/23/20 Original l LSB c z Figure 2 9 Site Plan WoodZWk om�a 17311.135th Ave. NE A•500 Wood —me , WA98072 Wonatch oOMIw 105 P,,,--Sl wenamnae. WA 98801 cC. 14251486-1889+Fa,481-2510 neilIXgeonmhmll 1509)665-7696l Fa,'. 665.7692 2 UNIFIED SOIL CLASSIFICATION SYSTEM GROUP MAJOR DIVISIONS GROUP NAME SYMBOL CLEAN GW WELL -GRADED, FINE TO COARSE GRAVEL COARSE- GRAVEL GRAVEL GP POORLY -GRADED GRAVEL GRAINED MORE THAN 50 % GRAVEL GM SILTY GRAVEL OF COARSE FRACTION RETAINED ON SOILS NO.4 SIEVE WITH FINES GC CLAYEY GRAVEL SAND CLEAN SW WELL -GRADED SAND, FINE TO COARSE SAND SAND SP POORLY GRADED SAND MORE THAN 50 % RETAINED ON MORE THAN 50 % NO. 200 SIEVE OF COARSE FRACTION SAND SM SILTY SAND PASSES NO. 4 SIEVE WITH FINES SC CLAYEY SAND FINE - SILT AND CLAY ML SILT INORGANIC GRAINED LIQUID LIMIT CL CLAY LESS THAN 50 % SOILS ORGANIC OL ORGANIC SILT, ORGANIC CLAY SILT AND CLAY MH SILT OF HIGH PLASTICITY, ELASTIC SILT INORGANIC MORE THAN 50 % PASSES LIQUID LIMIT CH CLAY OF HIGH PLASTICITY, FAT CLAY NO. 200 SIEVE 50 % OR MORE ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: 1) Field classification is based on visual SOIL MOISTURE MODIFIERS: examination of soil in general accordance with ASTM D 2488-93. Dry - Absence of moisture, dusty, dry to the touch 2) Soil classification using laboratory tests is based on ASTM D 2488-93. Moist - Damp, but no visible water. 3) Descriptions of soil density or Wet - Visible free water or saturated, consistency are based on usually soil is obtained from interpretation of blowcount data, below water table visual appearance of soils, and/or test data. Project Number Chen 210th St SW NELSON GEOTECHNICAL No. Date Revision By CK 1209720 Residential Development Infiltration IVGA ASSOCIATES, INC. GEOTECHNICAL ENGINEERS & GEOLOGISTS We dinville Office Wenatchee Office 1 10/23/20 Original DPN LSB Figure 3 Soil Classification Chart na,1-,65thA"e ..A-5°° Wenatchee, W1-135t lie .. 98W2 Wenatchee, WA t. (425) 48fi-1669 / Fax:481-2510 www. nelsongeotech.com (509) 665-769fi /Fax: 665-7fi92 LOG OF EXPLORATION DEPTH (FEET) USC SOIL DESCRIPTION TEST PIT 1 0.0 - 1.0 GRASS UNDERLAIN BY DARK BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, ROOTS, AND ORGANICS (LOOSE, MOIST) (TOPSOIL) 1.0 - 2.0 DARK BROWN TO BLACK SILTY FINE TO MEDIUM SAND WITH GRAVEL, ORGANICS AND DEBRIS (LOOSE, MOIST) (UNDOCUMENTED FILL) 2.0 - 3.0 BURIED TOPSOIL 3.0 - 9.5 SP-SM BROWN -GRAY, FINE TO MEDIUM SAND WITH SILT AND GRAVEL (MEDIUM DENSE TO DENSE, MOIST) SAMPLES WERE COLLECTED AT 5.0, 7.0, 9.0 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT COMPLETED AT 9.5 FEET ON 10/9/20 TEST PIT 2 0.0 - 1.0 DARK BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, ROOTS, AND ORGANICS (LOOSE, MOIST) (TOPSOIL) 1.0 - 9.5 SP-SM BROWN -GRAY, FINE TO MEDIUM SAND WITH SILT AND GRAVEL (MEDIUM DENSE TO DENSE, MOIST) SAMPLES WERE COLLECTED AT 4.0, 7.0, AND 8.5 FEET GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT COMPLETED AT 9.5 FEET ON 10/9/20 INFILTRATION PIT 101 0.0 - 1.0 DARK BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL, ROOTS, AND ORGANICS (LOOSE, MOIST) (TOPSOIL) 1.0 - 7.0 SP-SM BROWN -GRAY, FINE TO MEDIUM SAND WITH SILT AND GRAVEL (MEDIUM DENSE TO DENSE, MOIST) SAMPLES WERE NOT COLLECTED GROUNDWATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT COMPLETED AT 7.0 FEET ON 10/9/20 LSB:KMS NELSON GEOTECHNICAL ASSOCIATES, INC. FILE NO 1209720 FIGURE 4 Appendix E: Offsite Analysis Per City of Edmonds GIS, the Snohomish County On-line Property Information (SCOPI) interactive map and Snohomish County Drainage Inventory, accessed August 25, 2021 and Oct 21, 2024, there are no critical areas, including wetlands, on or adjacent to this project site. The project site is not mapped as a FEMA Floodway or FEMA Floodplain. There do not appear to be any records of drainage complaints on or adjacent to this project site. No evidence of run-on from adjacent parcels and roadways were observed during site visits conducted on October 1, 2019 and August 26, 2021. There was no evidence of other drainage related issues on the property, such as ponding or soft, saturated soils, or mushy top soil. Existing Site Hydrology: Existing site hydrology offsite analysis describes the existing drainage system for 1/4 mile from the project site. The site is generally flat with gentle slopes from north to south with grades of approximately 5%. The existing hard surfaces consist of a single -story dwelling unit, shed and carport, with a footprint totaling approximately 1,750 SF. The existing paved driveway is approximately 3,050 SF and is the only pollution generating surface onsite. There are several trees around the perimeter of the site. The rest of the site is lawn. Refer to Appendix A for the survey showing existing conditions. Current storm water runoff from the roofs are discharged to the surrounding lawn surface via downspouts and sheet flow from the carport roof. Runoff follows the existing grade of the site towards 210th St SW and into the curb and gutter drainage system along 210th ST SW. Existing driveway runoff sheet flows to a catch basin and into the same curb and gutter drainage system along 210th ST SW. Per City of Edmonds GIS Web Map and our official survey, there is an existing 12" concrete storm pipe along 210th ST SW that conveys runoff from the catch basin west until it reaches a manhole at the junction of 210th ST SW and 72nd Ave W, where another 12" concrete pipe conveys the runoff south until it reaches a manhole at 212th ST SW; a 36" concrete pipe then continues to convey the runoff south along 72nd Ave W to a manhole at 216th ST SW. Another 36" concrete pipe continues to convey the runoff east along 216th ST SW beyond the 1/4 mile scope of this analysis. Ultimate outfall is Halls Creek via a 36" concrete pipe in the City of Lynnwood's jurisdiction. There is no evidence of downstream flooding and no drainage complaints related to this parcel. Field observations conducted during and after rain events observed no runoff from adjacent sites onto the project site. The project site has roads to the west, east and south that collect stormwater to public drains. No runoff from the north residential property was observed to enter the project site, presumably due to its drainage collection system and the existing lawn. There are no known critical areas onsite or adjacent to the site. Soils are mostly advance outwash deposits and glacial till. Test pits with depths of 7.0 to 9.5 feet did not encounter any groundwater. Refer to the Geotechnical Report in Appendix D for more details. There appears to be one Threshold Discharge Area (TDA) onsite. Runoff from the existing roof and driveway currently runs off across the lawn (with a few scattered trees) towards 210th ST SW. The Page 11 existing outfall is the public storm system along 210th ST SW. There is an existing curb and gutter system adjacent to the project site that leads to a catch basin in the right of way along 210th ST SW. Infiltration of stormwater does appear to occur in lawn areas of the project site. No standing water or pooling was observed onsite. Any additional runoff from the hard surfaces follows the asphalt driveway towards 210th ST SW and follows the road grade toward an existing public catch basin to the southwest. Some standing water below the inverts of the incoming and outgoing storm pipes were observed in the public catch basin on 210th ST SW on October 1, 2019. No water was observed in the catch basin on August 26, 2021. Developed Site Hvdroloev: Existing infiltration of storm water is preserved to the maximum extent feasible. Downspouts collect stormwater from the proposed building roof and conveys runoff to the proposed infiltration trench. The driveway is graded to collect all stormwater from the proposed driveway to a proposed catch basin onsite, which then conveys the runoff to the proposed infiltration trench. The proposed infiltration facility is sized and intended to keep stormwater runoff onsite. Refer to Appendix A for drainage design details and Appendix G for infiltration sizing analysis. As shown in the infiltration sizing analysis, no increase in stormwater flow offsite is anticipated. Due to the design of the infiltration trench to infiltration 100% of the runoff from the roof and driveway, storm water runoff is not anticipated to leave the project site. The project is not anticipated to cause any backwater effects due to the nature of the project. Page 12 Appendix F: Operation and Maintenance Manual Page 13 V-4.6 Maintenance Standards for Drainage Facilities The facility -specific maintenance standards contained in this section are intended to be conditions for determining if maintenance actions are required as identified through inspection. They are not intended to be measures of the facility's required condition at all times between inspections. In other words, exceedence of these conditions at any time between inspections and/or maintenance does not automatically constitute a violation of these standards. However, based upon inspection observations, the inspection and maintenance schedules shall be adjusted to minimize the length of time that a facility is in a condition that requires a maintenance action. Table V-4.5.2(1) Maintenance Standards - Detention Ponds Maintenance Defect Conditions When Results Expected When Component Maintenance Is Needed Maintenance Is Performed General Any trash and debris which exceed 1 cubic feet per 1,000 square feet. In general, there should be no visual evidence of dumping. rash & Debris If less than threshold all trash and debris will be removed as part of next scheduled maintenance. Any poisonous or nuisance vegetation which may constitute a hazard to maintenance personnel or the public. Poisonous Any evidence of noxious Vegetation and noxious weeds weeds as defined by State or local regulations. (Apply requirements of adopted IPM policies for the use of herbicides). Trash and debris cleared from site No danger of poisonous vegetation where maintenance personnel or the public might normally be. (Coordinate with local health department) Complete eradication of noxious weeds may not be possible. Compliance with State or local eradication policies required Maintenance Defect Conditions When Results Expected When Component Maintenance Is Needed Maintenance Is Performed Any evidence of oil, gasoline, contaminants or other pollutants Contaminants No contaminants or pollutants and Pollution (Coordinate removal/cleanup present. with local water quality response agency). Any evidence of rodent holes if Rodents destroyed and dam or facility is acting as a dam or berm repaired. (Coordinate with Rodent Holes berm, or any evidence of water local health department; coordinate piping through dam or berm with Ecology Dam Safety Office if via rodent holes. pond exceeds 10 acre-feet.) Beaver Dams Dam results in change or function of the facility. When insects such as wasps Insects and hornets interfere with maintenance activities. Facility is returned to design function. (Coordinate trapping of beavers and removal of dams with appropriate permitting agencies) Insects destroyed or removed from site. pply insecticides in compliance adopted IPM policies Maintenance Defect Conditions When Results Expected When Component Maintenance Is Needed Maintenance Is Performed Tree growth does not allow maintenance access or interferes with maintenance activity (i.e., slope mowing, silt removal, vectoring, or Trees do not hinder maintenance equipment movements). If activities. Harvested trees should trees are not interfering with be recycled into mulch or other Tree Growth and access or maintenance, do not beneficial uses (e.g., alders for Hazard Trees remove firewood). If dead, diseased, or dying Remove hazard Trees trees are identified (Use a certified Arborist to determine health of tree or removal requirements) Slopes should be stabilized using a appropriate erosion control Eroded damage over 2 inches measure(s); e.g.,rock deep where cause of damage reinforcement, planting of grass, is still present or where there is Side Slopes of p Erosion potential for continued erosion. compaction. Pond If erosion is occurring on Any erosion observed on a compacted berms a licensed civil compacted berm embankment. engineer should be consulted to resolve source of erosion. Accumulated sediment that exceeds 10% of the designed Sediment cleaned out to designed Sediment pond depth unless otherwise pond shape and depth; pond Storage Area specified or affects inletting or reseeded if necessary to control outletting condition of the erosion. facility. Liner (if Liner is visible and has more Liner repaired or replaced. Liner is Applicable) than three 1/4-inch holes in it. fully covered. Maintenance Defect Conditions When Results Expected When Component Maintenance Is Needed Maintenance Is Performed Any part of berm which has settled 4 inches lower than the design elevation If settlement is apparent, measure berm to determine amount of settlement Settlements Dike is built back to the design elevation. Settling can be an indication of more severe problems with the berm or outlet works. A licensed civil engineer should Ponds Berms (Dikes) be consulted to determine the source of the settlement. Discernable water flow through pond berm. Ongoing erosion with potential for erosion to continue. Piping Piping eliminated. Erosion potential (Recommend a Goethechnical resolved. engineer be called in to inspect and evaluate condition and recommend repair of condition. Emergency Tree growth on emergency Overflow/ Spillway and spillways creates blockage Berms over 4 feet problems and may cause in height failure of the berm due to Trees should be removed. If root system is small (base less than 4 uncontrolled overtopping. inches) the root system may be left Tree Growth in place. Otherwise the roots Tree growth on berms over 4 should be removed and the berm feet in height may lead to restored. A licensed civil engineer should be consulted for proper piping through the berm which berm/spillway restoration. could lead to failure of the berm. Maintenance Defect Conditions When Results Expected When Component Maintenance Is Needed Maintenance Is Performed Discernable water flow through pond berm. Ongoing erosion with potential for erosion to continue. Piping Piping eliminated. Erosion potential (Recommend a Goethechnical resolved. engineer be called in to inspect and evaluate condition and recommend repair of condition. Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the Emergency Emergency Rocks and pad depth are restored Overflow/Spillway Overflow/Spillway top of out flow path of spillway. to design standards. (Rip -rap on inside slopes need not be replaced.) Erosion See "Side Slopes of Pond" Table V-4.5.2(2) Maintenance Standards - Infiltration Results Expected Maintenance When Defect Conditions When Maintenance Is Needed Component Maintenance Is Performed See "Detention Trash & Debris See "Detention Ponds" (No. 1). Ponds" (No. 1). Poisonous/Noxious See "Detention See "Detention Ponds" (No. 1). Vegetation Ponds" (No. 1). General Contaminants and See "Detention See "Detention Ponds" (No. 1). Pollution Ponds" (No. 1). See "Detention Rodent Holes See "Detention Ponds" (No. 1). Ponds" (No. 1) Results Expected Maintenance When Defect Conditions When Maintenance Is Needed Component Maintenance Is Performed Water ponding in infiltration pond after rainfall ceases and appropriate time allowed for infiltration. Treatment basins should infiltrate Sediment is Water Quality Design Storm Volume within 48 removed and/or hours, and empty within 24 hours after cessation facility is cleaned Storage Area Sediment of most rain events. so that infiltration system works (A percolation test pit or test of facility indicates according to facility is only working at 90% of its designed design. capabilities. Test every 2 to 5 years. If two inches or more sediment is present, remove). Filled with Filter bag is Filter Bags (if Sediment and Sediment and debris fill bag more than 1/2 full. replaced or system applicable) Debris is redesigned. Sediment and By visual inspection, little or no water flows Gravel in rock filter Rock Filters Debris through filter during heavy rain storms. is replaced. Side Slopes See "Detention Erosion See "Detention Ponds" (No. 1). of Pond Ponds" (No. 1). Emergency See "Detention Tree Growth See "Detention Ponds" (No. 1). Overflow Ponds" (No. 1). Spillway and Berms over 4 See "Detention Piping See "Detention Ponds" (No. 1). feet in height. Ponds" (No. 1). See "Detention Rock Missing See "Detention Ponds" (No. 1). Emergency Ponds" (No. 1). Overflow Spillway See "Detention Erosion See "Detention Ponds" (No. 1). Ponds" (No. 1). Results Expected Maintenance When Defect Conditions When Maintenance Is Needed Component Maintenance Is Performed Facility or sump Pre -settling filled with Sediment is Ponds and 6" or designed sediment trap depth of sediment. Sediment and/or removed. Vaults debris Table V-4.5.2(3) Maintenance Standards - Closed Detention Systems (Tanks/Vaults) Results Expected Maintenance When Defect Conditions When Maintenance is Needed Component Maintenance is Performed Storage Area One-half of the cross section of a vent is Vents open and Plugged Air Vents blocked at any point or the vent is damaged. functioning. Accumulated sediment depth exceeds 10% of the diameter of the storage area for 1/2 length of storage vault or any point depth exceeds 15% of All sediment and Debris and diameter. debris removed Sediment (Example: 72-inch storage tank would require from storage area. cleaning when sediment reaches depth of 7 inches for more than 1/2 length of tank.) Any openings or voids allowing material to be Joints Between transported into facility. All joint between tank/pipe sections Tank/Pipe Section (Will require engineering analysis to determine are sealed. structural stability). Any part of tank/pipe is bent out of shape more Tank/pipe repaired Tank Pipe Bent Out than 10% of its design shape. (Review required or replaced to of Shape by engineer to determine structural stability). design. Maintenance Condition When Maintenance is Results Expected When Defect Component Needed Maintenance is Performed Any trash or debris blocking (or Overflow Pipe is free of all obstructions and Obstructions having the potential of blocking) Pipe works as designed. the overflow pipe. See "Closed Detention See "Closed Detention See "Closed Detention Systems"-] Manhole Systems"❑ (No. Systems" (No. 3). (No. 3). 3). See "Catch Catch Basin Basins" (No. See "Catch Basins" (No. 5). See "Catch Basins"L (No. 5). 5). Table V-4.5.2(5) Maintenance Standards - Catch Basins Results Expected Maintenance Defect Conditions When Maintenance is Needed When Component Maintenance is performed Results Maintenance Expected Defect Conditions When Maintenance is Needed When Component Maintenance is performed General No Trash or Trash or debris which is located immediately in front of debris located the catch basin opening or is blocking inletting capacity immediately in of the basin by more than 10%. front of catch basin or on Trash or debris (in the basin) that exceeds 60 percent of grate opening. the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the basin, but in no No trash or case less than a minimum of six inches clearance from debris in the Trash & the debris surface to the invert of the lowest pipe. catch basin. Debris Trash or debris in any inlet or outlet pipe blocking more Inlet and outlet than 1/3 of its height. pipes free of trash or debris. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., No dead methane). animals or vegetation present within the catch basin. Sediment (in the basin) that exceeds 60 percent of the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the basin, but in no No sediment in Sediment case less than a minimum of 6 inches clearance from the the catch basin sediment surface to the invert of the lowest pipe. Results Expected Maintenance Defect Conditions When Maintenance is Needed When Component Maintenance is performed Top slab is free Top slab has holes larger than 2 square inches or cracks of holes and Structure wider than 1/4 inch. (Intent is to make sure no material is cracks. Damage to running into basin). Frame is sitting Frame and/or Frame not sitting flush on top slab, i.e., separation of flush on the riser Top Slab more than 3/4 inch of the frame from the top slab. Frame rings or top slab not securely attached and firmly attached. Basin replaced or repaired to Maintenance person judges that structure is unsound. Fractures or design Cracks in Grout fillet has separated or cracked wider than 1/2 inch standards. Basin Walls/ and longer than 1 foot at the joint of any inlet/outlet pipe Pipe is Bottom or any evidence of soil particles entering catch basin regrouted and through cracks. secure at basin wall. Basin replaced Settlement/ If failure of basin has created a safety, function, or design or repaired to Misalignment problem. design standards. No vegetation blocking Vegetation growing across and blocking more than 10% opening to of the basin opening. Vegetation basin. Vegetation growing in inlet/outlet pipe joints that is more No vegetation or than six inches tall and less than six inches apart. root growth present. Results Expected Maintenance Defect Conditions When Maintenance is Needed When Component Maintenance is performed Contamination No pollution See "Detention Ponds" (No. 1). and Pollution present. Cover Not in Cover is missing or only partially in place. Any open Catch basin Place catch basin requires maintenance. cover is closed Locking Mechanism cannot be opened by one maintenance Mechanism Mechanism person with proper tools. Bolts into frame have less than opens with Catch Basin Not Working 1/2 inch of thread. proper tools. Cover One maintenance person cannot remove lid after Cover can be Cover Difficult applying normal lifting pressure. removed by one to Remove (Intent is keep cover from sealing off access to maintenance maintenance.) person. Ladder meets design Ladder is unsafe due to missing rungs, not securely standards and Ladder Rungs Ladder attached to basin wall, misalignment, rust, cracks, or allows Unsafe sharp edges. maintenance person safe access. Metal Grates Grate opening Grate opening (If Grate with opening wider than 7/8 inch. meets design Unsafe Applicable) standards. Grate free of Trash and Trash and debris that is blocking more than 20% of grate trash and Debris surface inletting capacity. debris. Results Expected Maintenance Defect Conditions When Maintenance is Needed When Component Maintenance is performed Grate is in place Damaged or and meets Grate missing or broken member(s) of the grate. Missing. design standards. Table V-4.5.2(6) Maintenance Standards - Debris Barriers (e.g., Trash Racks) Maintenance Condition When Maintenance is Results Expected When Defect Components Needed Maintenance is Performed Trash and Trash or debris that is plugging more than Barrier cleared to design flow General Debris 20% of the openings in the barrier. capacity. Bars in place with no bends Bars are bent out of shape more than 3 more than 3/4 inch. inches. Damaged/ Bars in place according to Missing Bars are missing or entire barrier missing. design. Bars. Metal Bars are loose and rust is causing 50% Barrier replaced or repaired to deterioration to any part of barrier. design standards. Inlet/Outlet Debris barrier missing or not attached to Barrier firmly attached to pipe Pipe pipe Table V-4.5.2(7) Maintenance Standards - Energy Dissipaters Results Expected Maintenance Defect Conditions When Maintenance is Needed When Components Maintenance is Performed External: Appendix G: WWHM Infiltration Trench Data The following WWHM Report shows that the proposed infiltration trench is sized to achieve LID performance standards. Page 14 WWHM2012 PROJECT REPORT General Model Information WWHM2012 Project Name: 2024-05-26 BK Townhomes Site Name: BK TOWNHOMES Site Address: 7103 210TH ST SW City: EDMONDS Report Date: 5/29/2024 MGS Region: Puget East Data Start: 1901 /10/1 Data End: 2058/09/30 Timestep: 15 Minute DOT Data Number03 Version Date: 2023/01 /27 Version: 4.2.19 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year 2024-05-26 BK Townhomes 5/29/2024 9:05:31 PM Page 2 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Mod 0.26 Pervious Total 0.26 Impervious Land Use acre Impervious Total 0 Basin Total 0.26 2024-05-26 BK Townhomes 5/29/2024 9:05:31 PM Page 3 Mitigated Land Use Infiltrated Hard Surfaces Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 0.112 ROADS FLAT 0.072 Impervious Total 0.184 Basin Total 0.184 2024-05-26 BK Townhomes 5/29/2024 9:05:31 PM Page 4 SHEET FLOW HARD SURFACE Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre SIDEWALKS FLAT 0.0196 Impervious Total 0.0196 Basin Total 0.0196 2024-05-26 BK Townhomes 5/29/2024 9:05:31 PM Page 5 LAWN & VEGETATED AREAS Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat 0.0564 Pervious Total 0.0564 Impervious Land Use acre Impervious Total 0 Basin Total 0.0564 2024-05-26 BK Townhomes 5/29/2024 9:05:31 PM Page 6 Routing Elements Predeveloped Routing 2024-05-26 BK Townhomes 5/29/2024 9:05:31 PM Page 7 Mitigated Routing Gravel Trench Bed 1 Bottom Length: Bottom Width: Trench bottom slope 1: Trench Left side slope 0: Trench right side slope 2: Material thickness of first layer: Pour Space of material for first layer: Material thickness of second layer: Pour Space of material for second layer: Material thickness of third layer: Pour Space of material for third layer: Infiltration On Infiltration rate: Infiltration safety factor: Total Volume Infiltrated (ac-ft.): Total Volume Through Riser (ac-ft.): Total Volume Through Facility (ac-ft.): Percent Infiltrated: Total Precip Applied to Facility: Total Evap From Facility: Discharge Structure Riser Height: 3.5 ft. Riser Diameter: 24 in. Element Flows To: Outlet 1 Outlet 2 36.00 ft. 5.00 ft. 0 To 1 0 To 1 0 To 1 0 0 0 0 0 0 8 0.36 21.636 0.032 21.668 99.85 0 0 Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-%) Discharge(cfs) Infilt(cfs) 0.0000 0.004 0.000 0.000 0.000 0.0389 0.004 0.000 0.000 0.012 0.0778 0.004 0.000 0.000 0.012 0.1167 0.004 0.000 0.000 0.012 0.1556 0.004 0.000 0.000 0.012 0.1944 0.004 0.000 0.000 0.012 0.2333 0.004 0.001 0.000 0.012 0.2722 0.004 0.001 0.000 0.012 0.3111 0.004 0.001 0.000 0.012 0.3500 0.004 0.001 0.000 0.012 0.3889 0.004 0.001 0.000 0.012 0.4278 0.004 0.001 0.000 0.012 0.4667 0.004 0.001 0.000 0.012 0.5056 0.004 0.002 0.000 0.012 0.5444 0.004 0.002 0.000 0.012 0.5833 0.004 0.002 0.000 0.012 0.6222 0.004 0.002 0.000 0.012 0.6611 0.004 0.002 0.000 0.012 0.7000 0.004 0.002 0.000 0.012 0.7389 0.004 0.003 0.000 0.012 0.7778 0.004 0.003 0.000 0.012 0.8167 0.004 0.003 0.000 0.012 0.8556 0.004 0.003 0.000 0.012 0.8944 0.004 0.003 0.000 0.012 2024-05-26 BK Townhomes 5/29/2024 9:05:31 PM Page 8 0.9333 0.004 0.003 0.000 0.012 0.9722 0.004 0.004 0.000 0.012 1.0111 0.004 0.004 0.000 0.012 1.0500 0.004 0.004 0.000 0.012 1.0889 0.004 0.004 0.000 0.012 1.1278 0.004 0.004 0.000 0.012 1.1667 0.004 0.004 0.000 0.012 1.2056 0.004 0.005 0.000 0.012 1.2444 0.004 0.005 0.000 0.012 1.2833 0.004 0.005 0.000 0.012 1.3222 0.004 0.005 0.000 0.012 1.3611 0.004 0.005 0.000 0.012 1.4000 0.004 0.005 0.000 0.012 1.4389 0.004 0.005 0.000 0.012 1.4778 0.004 0.006 0.000 0.012 1.5167 0.004 0.006 0.000 0.012 1.5556 0.004 0.006 0.000 0.012 1.5944 0.004 0.006 0.000 0.012 1.6333 0.004 0.006 0.000 0.012 1.6722 0.004 0.006 0.000 0.012 1.7111 0.004 0.007 0.000 0.012 1.7500 0.004 0.007 0.000 0.012 1.7889 0.004 0.007 0.000 0.012 1.8278 0.004 0.007 0.000 0.012 1.8667 0.004 0.007 0.000 0.012 1.9056 0.004 0.007 0.000 0.012 1.9444 0.004 0.008 0.000 0.012 1.9833 0.004 0.008 0.000 0.012 2.0222 0.004 0.008 0.000 0.012 2.0611 0.004 0.008 0.000 0.012 2.1000 0.004 0.008 0.000 0.012 2.1389 0.004 0.008 0.000 0.012 2.1778 0.004 0.009 0.000 0.012 2.2167 0.004 0.009 0.000 0.012 2.2556 0.004 0.009 0.000 0.012 2.2944 0.004 0.009 0.000 0.012 2.3333 0.004 0.009 0.000 0.012 2.3722 0.004 0.009 0.000 0.012 2.4111 0.004 0.010 0.000 0.012 2.4500 0.004 0.010 0.000 0.012 2.4889 0.004 0.010 0.000 0.012 2.5278 0.004 0.010 0.000 0.012 2.5667 0.004 0.010 0.000 0.012 2.6056 0.004 0.010 0.000 0.012 2.6444 0.004 0.010 0.000 0.012 2.6833 0.004 0.011 0.000 0.012 2.7222 0.004 0.011 0.000 0.012 2.7611 0.004 0.011 0.000 0.012 2.8000 0.004 0.011 0.000 0.012 2.8389 0.004 0.011 0.000 0.012 2024-05-26 BK Townhomes 5/29/2024 9:05:31 PM Page 9 3.1889 0.004 0.013 0.000 0.012 3.2278 0.004 0.013 0.000 0.012 3.2667 0.004 0.013 0.000 0.012 3.3056 0.004 0.013 0.000 0.012 3.3444 0.004 0.013 0.000 0.012 3.3833 0.004 0.014 0.000 0.012 3.4222 0.004 0.014 0.000 0.012 3.4611 0.004 0.014 0.000 0.012 3.5000 0.004 0.014 0.000 0.012 2024-05-26 BK Townhomes 5/29/2024 9:05:31 PM Page 10 Analysis Results POC 1 0.01 F 0.01 0.00 Q iL 0.00 0.00 °� Cumulative Probability 001 — tam — i® Percent Time Exceetlir�g OS 1 2 5 10 27 30 50 10 80 90 95 99 99 99.5 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area: 0.26 Total Impervious Area: 0 Mitigated Landuse Totals for POC #1 Total Pervious Area: 0.0564 Total Impervious Area: 0.184 Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.003201 5 year 0.005007 10 year 0.006131 25 year 0.007441 50 year 0.008334 100 year 0.009159 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.000 0.037 1950 0.004 0.000 1951 0.003 0.000 1952 0.002 0.062 1953 0.002 0.053 1954 0.006 0.000 1955 0.005 0.000 1956 0.004 0.000 1957 0.005 0.000 1958 0.003 0.027 M. 2024-05-26 BK Townhomes 5/29/2024 9:05:31 PM Page 11 1959 0.003 0.000 1960 0.003 0.000 1961 0.003 0.025 1962 0.002 0.000 1963 0.003 0.000 1964 0.003 0.000 1965 0.003 0.016 1966 0.002 0.000 1967 0.005 0.000 1968 0.004 0.000 1969 0.002 0.000 1970 0.002 0.000 1971 0.004 0.032 1972 0.003 0.051 1973 0.002 0.000 1974 0.004 0.000 1975 0.003 0.038 1976 0.003 0.000 1977 0.001 0.000 1978 0.002 0.013 1979 0.005 0.000 1980 0.003 0.000 1981 0.002 0.000 1982 0.004 0.000 1983 0.003 0.000 1984 0.003 0.000 1985 0.005 0.000 1986 0.012 0.000 1987 0.004 0.002 1988 0.003 0.000 1989 0.002 0.000 1990 0.003 0.000 1991 0.004 0.000 1992 0.003 0.000 1993 0.002 0.000 1994 0.001 0.016 1995 0.003 0.000 1996 0.007 0.000 1997 0.013 0.000 1998 0.002 0.000 1999 0.003 0.000 2000 0.002 0.000 2001 0.000 0.000 2002 0.003 0.000 2003 0.002 0.000 2004 0.003 0.000 2005 0.003 0.000 2006 0.007 0.000 2007 0.005 0.000 2008 0.007 0.000 2009 0.003 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0132 0.0624 2 0.0121 0.0531 3 0.0073 0.0506 2024-05-26 BK Townhomes 5/29/2024 9:06:02 PM Page 12 4 0.0072 0.0380 5 0.0071 0.0369 6 0.0055 0.0315 7 0.0055 0.0271 8 0.0055 0.0254 9 0.0051 0.0165 10 0.0047 0.0159 11 0.0047 0.0130 12 0.0045 0.0016 13 0.0044 0.0000 14 0.0044 0.0000 15 0.0041 0.0000 16 0.0040 0.0000 17 0.0038 0.0000 18 0.0037 0.0000 19 0.0036 0.0000 20 0.0035 0.0000 21 0.0035 0.0000 22 0.0035 0.0000 23 0.0035 0.0000 24 0.0034 0.0000 25 0.0034 0.0000 26 0.0034 0.0000 27 0.0033 0.0000 28 0.0033 0.0000 29 0.0032 0.0000 30 0.0032 0.0000 31 0.0031 0.0000 32 0.0031 0.0000 33 0.0031 0.0000 34 0.0030 0.0000 35 0.0030 0.0000 36 0.0027 0.0000 37 0.0027 0.0000 38 0.0027 0.0000 39 0.0027 0.0000 40 0.0027 0.0000 41 0.0026 0.0000 42 0.0026 0.0000 43 0.0025 0.0000 44 0.0025 0.0000 45 0.0024 0.0000 46 0.0023 0.0000 47 0.0023 0.0000 48 0.0022 0.0000 49 0.0021 0.0000 50 0.0020 0.0000 51 0.0019 0.0000 52 0.0019 0.0000 53 0.0019 0.0000 54 0.0018 0.0000 55 0.0018 0.0000 56 0.0017 0.0000 57 0.0017 0.0000 58 0.0012 0.0000 59 0.0012 0.0000 60 0.0005 0.0000 61 0.0004 0.0000 2024-05-26 BK Townhomes 5/29/2024 9:06:02 PM Page 13 2024-05-26 BK Townhomes 5/29/2024 9:06:02 PM Page 14 Duration Flows The Facility PASSED Flow(cfs) Predev Mit Percentage Pass/Fail 0.0016 21087 194 0 Pass 0.0017 19239 192 0 Pass 0.0017 17541 191 1 Pass 0.0018 15960 190 1 Pass 0.0019 14510 189 1 Pass 0.0019 13274 188 1 Pass 0.0020 12151 188 1 Pass 0.0021 11114 185 1 Pass 0.0021 10181 183 1 Pass 0.0022 9345 183 1 Pass 0.0023 8615 183 2 Pass 0.0023 7937 182 2 Pass 0.0024 7332 182 2 Pass 0.0025 6731 182 2 Pass 0.0026 6218 181 2 Pass 0.0026 5707 180 3 Pass 0.0027 5232 179 3 Pass 0.0028 4795 179 3 Pass 0.0028 4398 177 4 Pass 0.0029 4062 177 4 Pass 0.0030 3754 177 4 Pass 0.0030 3480 176 5 Pass 0.0031 3210 173 5 Pass 0.0032 2947 170 5 Pass 0.0032 2725 165 6 Pass 0.0033 2543 165 6 Pass 0.0034 2385 164 6 Pass 0.0034 2248 163 7 Pass 0.0035 2120 161 7 Pass 0.0036 2004 161 8 Pass 0.0036 1904 161 8 Pass 0.0037 1789 161 8 Pass 0.0038 1685 160 9 Pass 0.0038 1590 159 10 Pass 0.0039 1485 159 10 Pass 0.0040 1384 158 11 Pass 0.0040 1321 158 11 Pass 0.0041 1250 157 12 Pass 0.0042 1201 156 12 Pass 0.0043 1157 154 13 Pass 0.0043 1119 152 13 Pass 0.0044 1075 152 14 Pass 0.0045 1031 152 14 Pass 0.0045 993 152 15 Pass 0.0046 964 151 15 Pass 0.0047 928 151 16 Pass 0.0047 895 151 16 Pass 0.0048 857 151 17 Pass 0.0049 822 151 18 Pass 2024-05-26 BK Townhomes 5/29/2024 9:06:02 PM Page 15 0.0052 683 145 21 Pass 0.0053 664 145 21 Pass 0.0053 645 145 22 Pass 0.0054 626 145 23 Pass 0.0055 607 144 23 Pass 0.0055 584 142 24 Pass 0.0056 567 142 25 Pass 0.0057 556 142 25 Pass 0.0057 541 142 26 Pass 0.0058 526 142 26 Pass 0.0059 515 142 27 Pass 0.0060 505 142 28 Pass 0.0060 495 142 28 Pass 0.0061 483 142 29 Pass 0.0062 471 140 29 Pass 0.0062 459 139 30 Pass 0.0063 443 137 30 Pass 0.0064 428 137 32 Pass 0.0064 417 136 32 Pass 0.0065 405 136 33 Pass 0.0066 388 136 35 Pass 0.0066 371 136 36 Pass 0.0067 355 135 38 Pass 0.0068 338 134 39 Pass 0.0068 325 132 40 Pass 0.0069 318 131 41 Pass 0.0070 307 130 42 Pass 0.0070 301 130 43 Pass 0.0071 292 130 44 Pass 0.0072 287 128 44 Pass 0.0072 279 127 45 Pass 0.0073 274 125 45 Pass 0.0074 268 125 46 Pass 0.0074 265 124 46 Pass 0.0075 262 124 47 Pass 0.0076 257 124 48 Pass 0.0077 253 123 48 Pass 0.0077 245 123 50 Pass 0.0078 242 122 50 Pass 0.0079 236 122 51 Pass 0.0079 231 122 52 Pass 0.0080 226 122 53 Pass 0.0081 224 122 54 Pass 0.0081 222 122 54 Pass 0.0082 220 122 55 Pass 0.0083 217 122 56 Pass 0.0083 211 122 57 Pass 2024-05-26 BK Townhomes 5/29/2024 9:06:02 PM Page 16 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. 2024-05-26 BK Townhomes 5/29/2024 9:06:02 PM Page 17 LID Report LID Technique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Gravel Trench Bed 1 POC Q 63.39 13 99.76 Total Volume Infiltrated 63.39 0 Oi 1 Q 00 99.76 0.00 0% No Treat. Credit Duration Compliance with LID Analysis Standard 8% of2-yr to 50% of Result= 2 yr Passed 2024-05-26 BK Townhomes 5/29/2024 9:06:02 PM Page 18 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. 2024-05-26 BK Townhomes 5/29/2024 9:06:09 PM Page 19 Appendix Predeveloped Schematic Basin 1 1 0.26ac 2024-05-26 BK Townhomes 5/29/2024 9:06:09 PM Page 20 Mitigated Schematic SHEE , Infiltrat L LAWN FLOW Hard VEGETATED HARD -Surfacl, AREAS SURFACE 0.06ac SI Gravel 'Trench Bed 1 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 21 Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 END GLOBAL 2009 09 30 UNIT SYSTEM FILES <File> <Un#> END FILES OPN SEQUENCE 1 <----------- File Name---------- -------------------->*** *** INGRP INDELT 00:15 PERLND 11 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<---------- Title ----------- >***TRAN PIVL DIG1 FIL1 1 Basin 1 MAX END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO PYR DIG2 FIL2 YRND 1 2 30 9 <PLS ><------- Name ------- >NBLKS Unit -systems Printer *** # - # User t-series Engl Metr *** in out *** 11 C, Forest, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 11 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 11 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT -INFO 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 22 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 11 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY 11 0 4.5 0.08 400 0.1 0.5 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 # - # ***PETMAX PETMIN INFEXP 11 0 0 2 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 # - # CEPSC UZSN NSUR 11 0.2 0.5 0.35 END PWAT-PARM4 AGWRC 0.996 *** INFILD DEEPFR BASETP AGWETP 2 0 0 0 *** INTFW IRC LZETP *** 6 0.5 0.7 PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS 11 0 0 0 0 2.5 1 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><------- Name ------- > END GEN-INFO *** Section IWATER*** Unit -systems Printer *** User t-series Engl Metr *** in out *** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT -INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATEI GWVS 0 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 23 END IMPLND SCHEMATIC <-Source-> <Name> # Basin 1*** PERLND 11 PERLND 11 ******Routing****** END SCHEMATIC <--Area--> <-Target-> MBLK <-factor-> <Name> # Tbl# 0.26 COPY 501 12 0.26 COPY 501 13 NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------ >< --- > User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT -INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------ ><-------- ><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><-------- > <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC -ACTIONS END SPEC -ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 0.8 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 0.8 IMPLND 1 999 EXTNL PREC 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 24 WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS -LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS -LINK 12 PERLND PWATER SURD 0.083333 COPY INPUT MEAN END MASS -LINK 12 MASS -LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS -LINK 13 END MASS -LINK END RUN 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 25 Mitigated UC/ File RUN GLOBAL WWHM4 model simulation START 1901 10 01 END RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 END GLOBAL 2058 09 30 UNIT SYSTEM FILES <File> <Un#> END FILES OPN SEQUENCE 1 <----------- File Name---------- -------------------->*** *** INGRP INDELT 00:15 IMPLND 4 IMPLND 1 RCHRES 1 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<---------- Title ----------- >***TRAN PIVL DIG1 FILL 1 Gravel Trench Bed 1 MAX END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO PYR DIG2 FIL2 YRND 1 2 30 9 <PLS ><------- Name ------- >NBLKS Unit -systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* END PRINT -INFO 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 26 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 # - # ***PETMAX PETMIN INFEXP END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 # - # CEPSC UZSN NSUR END PWAT-PARM4 AGWRC *** INFILD DEEPFR BASETP AGWETP *** INTFW IRC LZETP *** PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><------- Name ------- > Unit -systems Printer *** # - # User t-series Engl Metr *** in out *** 4 ROOF TOPS/FLAT 1 1 1 27 0 1 ROADS/FLAT 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 4 0 0 1 0 0 0 1 0 0 1 0 0 0 END ACTIVITY PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 4 0 0 4 0 0 4 1 9 1 0 0 4 0 0 0 1 9 END PRINT -INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 4 0 0 0 0 0 1 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 4 400 0.01 0.1 0.1 1 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 4 0 0 1 0 0 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 27 END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 4 0 0 1 0 0 END IWAT-STATEI END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK <Name> # <-factor-> <Name> # Tbl# Infiltrated Hard Surfaces*** IMPLND 4 0.112 RCHRES 1 5 IMPLND 1 0.072 RCHRES 1 5 ******Routing****** IMPLND 4 0.112 COPY 1 15 IMPLND 1 0.072 COPY 1 15 RCHRES 1 1 COPY 501 17 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems # - #<------------------ >< --- > User T-series in out 1 Gravel Trench Be-007 2 1 1 1 END GEN-INFO *** Section RCHRES*** Printer *** Engl Metr LKFG *** *** 28 0 1 ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT -INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** 1 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------ ><-------- ><-------- ><-------- ><-------- ><-------- ><-------- > *** 1 1 0.01 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 28 RCHRES Initial # - # *** VOL *** ac-ft <------ ><-------- > 1 0 END HYDR-INIT END RCHRES SPEC -ACTIONS END SPEC -ACTIONS FTABLES FTABLE 1 92 5 conditions for each HYDR section Initial value of COLIND for each possible exit <--- ><--- ><--- ><--- >< --- > *** 4.0 5.0 0.0 0.0 0.0 Depth Area Volume Outflowl Outflow2 (ft) (acres) (acre-ft) (cfs) (cfs) 0.000000 0.004132 0.000000 0.000000 0.000000 0.038889 0.004132 0.000161 0.000000 0.012000 0.077778 0.004132 0.000321 0.000000 0.012000 0.116667 0.004132 0.000482 0.000000 0.012000 0.155556 0.004132 0.000643 0.000000 0.012000 0.194444 0.004132 0.000803 0.000000 0.012000 0.233333 0.004132 0.000964 0.000000 0.012000 0.272222 0.004132 0.001125 0.000000 0.012000 0.311111 0.004132 0.001286 0.000000 0.012000 0.350000 0.004132 0.001446 0.000000 0.012000 0.388889 0.004132 0.001607 0.000000 0.012000 0.427778 0.004132 0.001768 0.000000 0.012000 0.466667 0.004132 0.001928 0.000000 0.012000 0.505556 0.004132 0.002089 0.000000 0.012000 0.544444 0.004132 0.002250 0.000000 0.012000 0.583333 0.004132 0.002410 0.000000 0.012000 0.622222 0.004132 0.002571 0.000000 0.012000 0.661111 0.004132 0.002732 0.000000 0.012000 0.700000 0.004132 0.002893 0.000000 0.012000 0.738889 0.004132 0.003053 0.000000 0.012000 0.777778 0.004132 0.003214 0.000000 0.012000 0.816667 0.004132 0.003375 0.000000 0.012000 0.855556 0.004132 0.003535 0.000000 0.012000 0.894444 0.004132 0.003696 0.000000 0.012000 0.933333 0.004132 0.003857 0.000000 0.012000 0.972222 0.004132 0.004017 0.000000 0.012000 1.011111 0.004132 0.004178 0.000000 0.012000 1.050000 0.004132 0.004339 0.000000 0.012000 1.088889 0.004132 0.004500 0.000000 0.012000 1.127778 0.004132 0.004660 0.000000 0.012000 1.166667 0.004132 0.004821 0.000000 0.012000 1.205556 0.004132 0.004982 0.000000 0.012000 1.244444 0.004132 0.005142 0.000000 0.012000 1.283333 0.004132 0.005303 0.000000 0.012000 1.322222 0.004132 0.005464 0.000000 0.012000 1.361111 0.004132 0.005624 0.000000 0.012000 1.400000 0.004132 0.005785 0.000000 0.012000 1.438889 0.004132 0.005946 0.000000 0.012000 1.477778 0.004132 0.006107 0.000000 0.012000 1.516667 0.004132 0.006267 0.000000 0.012000 1.555556 0.004132 0.006428 0.000000 0.012000 1.594444 0.004132 0.006589 0.000000 0.012000 1.633333 0.004132 0.006749 0.000000 0.012000 1.672222 0.004132 0.006910 0.000000 0.012000 1.711111 0.004132 0.007071 0.000000 0.012000 1.750000 0.004132 0.007231 0.000000 0.012000 1.788889 0.004132 0.007392 0.000000 0.012000 1.827778 0.004132 0.007553 0.000000 0.012000 1.866667 0.004132 0.007713 0.000000 0.012000 1.905556 0.004132 0.007874 0.000000 0.012000 1.944444 0.004132 0.008035 0.000000 0.012000 1.983333 0.004132 0.008196 0.000000 0.012000 2.022222 0.004132 0.008356 0.000000 0.012000 2.061111 0.004132 0.008517 0.000000 0.012000 2.100000 0.004132 0.008678 0.000000 0.012000 *** Initial value of OUTDGT for each possible exit <--- ><--- ><--- ><--- >< --- > 0.0 0.0 0.0 0.0 0.0 Velocity Travel Time*** (ft/sec) (Minutes)*** 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 29 2.138889 0.004132 0.008838 0.000000 0.012000 2.177778 0.004132 0.008999 0.000000 0.012000 2.216667 0.004132 0.009160 0.000000 0.012000 2.255556 0.004132 0.009320 0.000000 0.012000 2.294444 0.004132 0.009481 0.000000 0.012000 2.333333 0.004132 0.009642 0.000000 0.012000 2.372222 0.004132 0.009803 0.000000 0.012000 2.411111 0.004132 0.009963 0.000000 0.012000 2.450000 0.004132 0.010124 0.000000 0.012000 2.488889 0.004132 0.010285 0.000000 0.012000 2.527778 0.004132 0.010445 0.000000 0.012000 2.566667 0.004132 0.010606 0.000000 0.012000 2.605556 0.004132 0.010767 0.000000 0.012000 2.644444 0.004132 0.010927 0.000000 0.012000 2.683333 0.004132 0.011088 0.000000 0.012000 2.722222 0.004132 0.011249 0.000000 0.012000 2.761111 0.004132 0.011410 0.000000 0.012000 2.800000 0.004132 0.011570 0.000000 0.012000 2.838889 0.004132 0.011731 0.000000 0.012000 2.877778 0.004132 0.011892 0.000000 0.012000 2.916667 0.004132 0.012052 0.000000 0.012000 2.955556 0.004132 0.012213 0.000000 0.012000 2.994444 0.004132 0.012374 0.000000 0.012000 3.033333 0.004132 0.012534 0.000000 0.012000 3.072222 0.004132 0.012695 0.000000 0.012000 3.111111 0.004132 0.012856 0.000000 0.012000 3.150000 0.004132 0.013017 0.000000 0.012000 3.188889 0.004132 0.013177 0.000000 0.012000 3.227778 0.004132 0.013338 0.000000 0.012000 3.266667 0.004132 0.013499 0.000000 0.012000 3.305556 0.004132 0.013659 0.000000 0.012000 3.344444 0.004132 0.013820 0.000000 0.012000 3.383333 0.004132 0.013981 0.000000 0.012000 3.422222 0.004132 0.014141 0.000000 0.012000 3.461111 0.004132 0.014302 0.000000 0.012000 3.500000 0.004132 0.014463 0.000000 0.012000 3.538889 0.004132 0.014624 0.162750 0.012000 END FTABLE 1 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 DIV PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 DIV IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** RCHRES 1 HYDR RO 1 1 1 WDM 1000 FLOW ENGL REPL RCHRES 1 HYDR 0 1 1 1 WDM 1001 FLOW ENGL REPL RCHRES 1 HYDR 0 2 1 1 WDM 1002 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1003 STAG ENGL REPL COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS -LINK <Volume> <-Grp> <Name> MASS -LINK IMPLND IWATER END MASS -LINK <-Member-><--Mult--> <Name> # #<-factor-> 5 SURO 0.083333 5 MASS -LINK 15 IMPLND IWATER SURO 2024-05-26 BK Townhomes 0.083333 <Target> <Name> RCHRES COPY 5/29/2024 9:06:10 PM <-Grp> <-Member->*** <Name> # #*** INFLOW IVOL INPUT MEAN Page 30 END MASS -LINK 15 MASS -LINK 17 RCHRES OFLOW OVOL 1 COPY INPUT MEAN END MASS -LINK 17 END MASS -LINK END RUN 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 31 Predeveloped HSPF Message File 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 32 Mitigated HSPF Message File 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 33 Disclaimer Legal Notice This program and accompanying documentation are provided 'as -is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by: Clear Creek Solutions, Inc. 2005-2024; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com 2024-05-26 BK Townhomes 5/29/2024 9:06:10 PM Page 34