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APPROVED_Storm_Drainage_Report+12.6.2022_4.06.02_PM+3255425RAM Engineering To: City of Edmonds Engineering Division From: Rob Long, PE RAM Engineering Subject: Select Homes 88th Ave W Short Plat- Lot 3 Stormwater Memo RAM Job No. 21-001 RESUB .......... 07 20225 Memorandum Date: December 2, 2022 BLD2022-1092 COMPLIES WITH APPLICABLE CITY STORM CODE 12/07/2022 This memo provides a summary of the stormwater drainage control system for Lot 3 of the 88th Ave W Short Plat (PLN 2021-0021). Ajoint infiltration trench installed with the short plat improvements will mitigate the stormwater impacts of the new, replaced, and existing hard surfaces of the 3-lot short plat. Lot 3 was originally allocated 3,720 sf of hard surface. The driveway area of Lot 3 has been slightly increased (100 sf) and thus the new hard surface allocation for Lot 3 is 3,820 sf. A summary of the hard surface allocation for Lot 3 is provided in the table and exhibit below, and an updated stormwater modeling (WWWHM2012) output has been attached for reference. In addition to the infiltration system, the lawn and landscape areas will be managed by BMP T5.13 post - construction soil quality and depth (soil amendments). Below is a stormwater control summary table for Lot 3: Lot 3 Stormwater Control Summary: Project Site Category: Category 2 (part of the 88th Ave W 2-Lot Short Plat) Discharge Location: City's Municipal Separate Storm Sewer System (MS4) Type of Area Square Footage Stormwater Facility Lawn and Landscape 9,478 sf Soil Amendments (BMP T5.13) Roof 2,610 sf Infiltration Trench Hard Surfaces 1,210 sf Infiltration Trench (Driveway/Apron, Walk and Patio) 25% Retrofit 0 SF None P M Engineering 19109 36"Ave W, Suite 100 Lynnwood WA 98036 (425) 678-6960 RAMengineeringinc.com Select Homes 88th Ave W Short Plot- Lot 3 Page 2 of 3 Stormwater Memo RAM lob No. 21-001 Select Homes 88t" Ave W Short Plat- Lot 3 Hard Surface Summary: Roof = 2,610 sf Driveway = 1,175 sf Sidewalk/Patio = 35 sf Total = 3,820 sf INSTALL E-ONE DH151 GRWDER KW CITY OF EDMO DS w/I 114" TO 1-1/2' CO RLER r } (SE NAH. ON SHT DT--M) WALK= 35 SF 1E 4� Mar, ((W) N rE !-1f?".T3Rr (O11'� E ONE :CONTROL PANEL AND ALARM I 4';`•�. _ 4- FW SEVER SERNCE (PONER FRAIL HOUR ELECTRICAL PANEL) LINE Roof = 2,610 SF (r IE O PLW) — — APPOOK A.Ac rr FREE LOcA Trcvrs (4 rsEo o} - - _ $FE FREE RE7°LACDfENT PLAN L-r er MC WA TER h0SF ae 07 345.92 MAIM NOISE PLLW&W .... �15"W 17i. i5'vJ. WSTALL FOUNDATION/FODjWG DRAIN o SA2. 47 -"' Y 3' MAN h4TGHT ROLERY 7O ✓4E ALONG BUN.OMrG RERANFTER FOOTINGS - iRIlCTEO AS PART QF 7FA 88TTi AYE PER FO01WC DRAW OETAX BY EARTH "! .g:.u4 - -- aays NW pM 9vEEr Dr-m ry eOL f —0 W01ORT PLAT (vwM2r-Oa rJ j (7YP) V T-r "NA rEA f vi�'�'•.:!,'•"'..: ----- L: fo' MAN UN07T r FDaTx�c a� _ DRAIN ORYNEEL TRpvE?r 352. os Mao - CFDTECH T54 a FG MANNEL DRAIN eoMM nmA noNsy c 8 TOR M4y40 rNc14Th' ENO) I � � .:• FOP a5,�20 (SaDHr END) � 1 �` #.FX TRA RAN . rRENL71 1 '.. NOS PRO GWAA741uET. GRAM! I '' ^ rNSTALLfD AS PART OFL1__ _ — 9 _ OR ARPROYEO EQUAL If 1 13,2H$ 5F 3 r N (S<FF DETAIL ON S!T OT-Ol} 4" PVC FTr I Y1071NG J � i PMW05LO wauSE --• a .. DRAIN a L of AM . r MAW FF ML00 ! . . r — — — — f NeAr PuwP r.l. -nisvE ctr; INSTAL. 1-14, PE (r'so P9) g - A' Ruc STORM (42Yi" rIGTJ GARAGE �_}.: . . - WATER SERYTCE lA1fE I Z DRAM! O I.OX AlIN FF J54.5O - - L V E 4rsot ° saco ra' eS@L I1 :.` wATLR LLHE) sNaer RLAr. ca�svEcr TO SrQRM SrE19 ;': COANEC.T IQ Lnae msru + as,lsrallcFEn As PApr of _ [ r PLAr — - 1. rE rsaot I, a (TRAL k N!R£ TO 6E W57ALLEO WTN I ti W 7100---�___ - - - - - - FAG o -� I l I lr. .✓° 1I N893T45'YY 57`45"IY 96.r5' !_1J� SS 1 x 350,5 SDW IE.-.i5}.S 1 EXLSTNJG FIOlISE I ' �- II - CSJURMON.. rrASCTED AS PBE ART 15' PRIYAT£: 353.0 A7' 7E ; ! i I ' DRAMIAGE FG OF -SHOP? PLAT E4iMEN7 EA&RWNT i r DRY UFUTAFS 27'DRAINAGE d XWT I ti UnarY EA--PWNr (T}P) `i ! DRIVEWAY = 1,175 SF Ipe SENERFORC£MAMJ I 1 2ao -r/2'. Re E2oo rsq I:.. r r I r NlnrTair�w. I /c.. . l ITMWN calms ,�sg j (RE54gai: aF PRENOUS SE NER _ 91ORT PEA T Md°ROYEML7VT5 TJf57(i'r AP$UEO AS PART S . r r+ TO 8E CGVrSTRLCTED AS 88TH AYF.w SNORT PLAT I PART OF THE serer AYE w (110 2021-0pal) I I I ■i << Iaer PLAT (PLH200-009e) ' -- i � 6 g& L. WASj, i0 x d R s 9 W \��GiTEg��� IONeT , 1Z/Z/ZOZZ Attachments: 1. Post Construction Soil Quality and Depth (Std Detail SD-642) 2. Updated Stormwater Modeling (WWWHM2012) Output (14 pages) RAM Engineering 1910936thAveW,Suite100 Lynnwood WA 98036 (425)678-6960 RAMengineeringinc.com Select Homes 88th Ave W Short Plat- Lot 3 Stormwater Memo RAM lob No. 21-001 Page 3 of 3 UNDISTURBED NATIVE VEGETATION 1�1►h]E,�i�1;1.3��7�/\IPI�Y�II� 2" ORGANIC MULCH 3" OF COMPOST INCORPORATED INTO 5" OF SITE SOIL (TOTAL AMENDED DEPTH OF 9.5", FOR A SETTLED DEPTH OF 8") SUBSOIL SCARIFIED 4" BELOW COMPOST AMENDED LAYER (12" BELOW SOIL SURFACE) 2" ORGANIC MULCH 6" IMPORTED TOPSOIL MIX (COMPACTED DEPTH) SUBSOIL IS SCARIFIED 6" BELOW IMPORTED TOPSOIL MIX UNDISTURBED PLANTS UNDISTURBED TURF (LAWN) (SEE NOTE 1) AREAS (SEE NOTE 1) PLANTING BEDS TURF (LAWN) AREAS 0 8" UNDISTURBED TURF/LAWN/LANDSCAPE A1all] &Ai11V.121 BIN 2LtILTA ��f]II SRASS: SEED OR SOD 1.75" OF COMPOST INCORPORATED NTO 6.25" OF SITE SOIL (TOTAL AMENDED DEPTH OF 9.5", FOR A SETTLED DEPTH OF 8") SUBSOIL SCARIFIED 4" BELOW COMPOST AMENDED LAYER (12" BELOW SOIL SURFACE) �PAL�c� 12" OPTION 2 — AMEND IN PLACE OR STOCKPILE AND AMEND GENERAL NOTES: PLANTING BEDS TURF (LAWN) AREAS ar�ag.Ey- pyr 1. AREAS OF NO DISTURBANCE ����������fl�il�����1���l1���♦I���♦�� j SHALL BE FENCED AND EXISTING /, / NNN l 44 GRASS: SEED VEGETATION AND SOIL SHALL BE j - I =1 1= I III- III—III=1_I I� I �I 11=1 11=1 0" 1-1I1-1IIt LII1=1I1-1I I �I 11=1 11=1 11=1 I I� I I-1 I I OR SOD PROTECTED FROM CONSTRUCTION IMPACTS. I I� I �I I I—III—III=1 I I� I III—III—III�I�III—III=1 11�1�111=III=III=111�1 I=1 I I=1 I I� I �I 11=1 11=1 I I I�III—III—III=111�1�111 1=III=111�1 III —III III 6" IMPORTED 2. TO MEASURE SETTLED DEPTH, WATER SOIL SUFFICIENTLY TO IIIIII111�T III— 1�7T—III=111�I�I TOPSOIL MIX FULLY SATURATE WITHOUT I I� �I 1=1 I —III —I I� III —III —I I I� I �I I I=11 I —I 11=III=III=III=III=III=III 1=1I 1=1 I� �I I1=1I 1=1I I f-1I 1=1 11=1 I1=1I I� I �I I I IIIIIII=III=III=III—III (COMPACTED CAUSING EROSION. 6" jT=_n I DEPTH) =�.— 3. COMPOST SHALL MEET SPEC. REQUIREMENTS IN THE 2017 1 II II EDMONDS STORMWATER SUBSOIL IS ADDENDUM (CHECKLIST 7). SCARIFIED 6" / BELOW 4. COMPACTION OF TOPSOIL (WHERE \�\ IMPORTED MRTEDMIX REQUIRED) TO BE TO 85% (MAX) -—TOPSOILOF 12 THE MAXIMUM DRY DENSITY OPTION 3 — IMPORT TOPSOIL PER MODIFIED PROCTOR TEST (ASTM D 1557). CITY OF EDMONDSI POST CONSTRUCTION SOIL QUALITY AND DEPTH PUBLIC WORKS DEPARTMENT APPROVED BY: REVISION DATE DECEMBER 2017 STANDARD DETAIL SD-642 RAM Engineering 19109 3611 Ave W, Suite 100 Lynnwood WA 98036 (425)678-6960 RAMengineeringinc.com Select Homes 88th Ave W Short Plat 3-Lot Short Plat PLN 2021- 0021 Updated December 2, 2022 DEVELOPED SITE HYDROLOGY: Developed Conditions. The proposed project includes the construction of a shared private road to access the existing house (to remain) and two new single-family residences, driveways and supporting utilities. The existing house onsite will remain on Lot 1 of the short plat; new impervious surface will be allocated to Lot 1 to construct a new driveway and walkway to the existing house. Per City of Edmonds standards, 25% of the existing hard surface associated with the existing house to remain shall be accounted for in the stormwater infiltration system; however due to the fact the existing house hard surface flows to the project infiltration system, all the Lot 1 hard surface will be accounted for in the design of the infiltration trench system. Landscaping and grass lawn around the new residence will stabilize the site upon building construction. The project proposes to create and/or replace 12,665 sf of hard surface, which includes all of the hard surface on Lot 1 (new, replaced and existing). The following is a summary of the proposed new/replaced and existing hard surface areas: Total Hard Surface to Mitigated=12,665 sf (0.290 ac) Lot 1 Hard Surface to Mitigate = 2,775 sf Existing House/covered patio to remain = 2,075 sf New Driveway for Area = 430 sf New Walkway/Patio Area = 270 sf Lot 2 Hard Surface to Mitigate = 6,070 sf Roof Area = 2,680 sf Driveway Area = 625 sf Walkway/Patio Area = 225 sf Shared Private Driveway = 2,540 sf (Located on Lot 2) Lot 3 Hard Surface to Mitigate = 3,820 sf Roof Area = 2,610 sf Driveway Area = 1,175 sf Walkway/Patio Area = 35 sf Total Pervious Surface (Lawn) = 29,161 sf (0.670 ac) The project proposes to implement full (100%) infiltration for all new and replaced hard surfaces onsite. In accordance with City Code (ECDC 18.30.060.D.5.b.i.), existing hard surfaces to remain shall apply stormwater management BMPs to a minimum of 25% of the existing unmanaged surfaces to remain. However, due to the fact the existing house hard surface flows to the project's infiltration system it has been sized to accommodate 100% of the Lot 1 hard surface (2,775 sf). The joint infiltration trench will be sized using the DOE 2012 Western Washington Hydrology Model (WWHM2012) continuous runoff model. RAMEngineering, Inc. RAM No. 21-001 Page 1 881n Ave W Short Plat Updated Stormwater Modeling WWHM2012 PROJECT REPORT Project Name: 21-001 Prelim Infil(2) Site Name: 88th 3-Lot Site Address: 21-001 City Report Date: 12/2/2022 MGS Regoin Puget East Data Start 1901/10/1 Data End : 2058/09/30 DOT Data Number: 03 Version Date: 2021/08/18 Version : 4.2.18 Low Flow Threshold for POC 1 : 50 Percent of the 2 Year High Flow Threshold for POC 1: 50 year PREDEVELOPED LAND USE Name : Basin 1 Bypass: No Groundwater: No Pervious Land Use acre C, Forest, Mod .96 Pervious Total 0.96 Impervious Land Use acre Impervious Total 0 Basin Total 0.96 Element Flows To: Surface Interflow MITIGATED LAND USE Name : Basin 1 Bypass: No Groundwater: No Pervious Land Use acre C, Pasture, Mod .67 Pervious Total 0.67 Impervious Land Use acre ROADS MOD 0.058 ROOF TOPS FLAT 0.169 DRIVEWAYS MOD 0.051 SIDEWALKS MOD 0.012 Impervious Total 0.29 Basin Total 0.96 Groundwater Element Flows To: Surface Interflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 RAM F_ngineering, Inc. 881" Ave W Short Plat RAM No. 21-001 Updated Stormwater Modeling Page 2 Name : Gravel Trench Bed 1 Bottom Length: 136.00 ft. Bottom Width: 29.00 ft. Trench bottom slope 1: 0 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 4 Pour Space of material for first layer: 0.35 Material thickness of second layer: 0 Pour Space of material for second layer: 0 Material thickness of third layer: 0 Pour Space of material for third layer: 0 Infiltration On Infiltration rate: 0.28 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 169.07 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 169.07 Percent Infiltrated: 100 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 4 ft. Riser Diameter: 8 in. Element Flows To: Outlet 1 Outlet 2 OR- 4W 711 SCENARIOS 11❑ Redeveloped❑� Mitigated Run Scenario Basic Elements ®WI®W M®8C KID Pro Elements PP W5711. LID Toolbox Commercial Toolbox Move Elements Save xy Loadxy OO� r I M Gravel Trench Bed 1 Mitigated Facility Name Downstream Connection Facility Type F- Precipitation Applied to Facility r :Evaporation Applied.to.Facility M 7 IGfavel Trench Bed 1 1 Outlet 1 Outlet 2 Outlet 3 0 0 0 Gravel TimxMed Quick Trench Facility Dimension Diagram Facility Dimensions Trench Length (It] 136 Trench Bottom Width (ft) 29 Effective Total Depth (ft) Top and bottom slope [HN) 0 Left Side Slope [HN) 0 Right Side Slope [HN) 0 Material Layers for Trench/Bed Layer 1 Thickness (ft) Layer 1 porosity, (0.1) Layer 2 Thickness (ft) 0 Layer 2 porosity (0-1) 0 Layer 3 Thickness (ft) 0 Layer 3 porosity (0-1) Infiltration Yes Measured Infiltration Rate (in/hr) 0.28 -`1 Reduction Factor (infilt'factor) Fi---'l Use Wetted Surface Area (sidewalls) N0 Total Volume Infiltrated (ac-ft) 169.07 Total Volume Through Riser (ac-ft) 0 Size Infiltration Trench Target %: 100 Outlet Structure Data I Riser Height (ft) F4 --=-' Riser Diameter (in) Riser Type Flat Notch Type Orifice Diameter Height Number (in) (ft) 1 Fo----! Fo----! 2 1-0---1 Fo----!l 3 Fa ---A F0---1 Trench Volume at Riser Head (ac-It) .121 Show Trench Open Table J Initial Stage (ft) 0 Total Volume Through Facility act 169.07 Percent Infiltrated 100 RAM F_ngineering, Inc. RAM No. 21-001 Page 3 ggrh Ave W Short Plat Updated Stormwater Modeling Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) 0.0000 0.090 0.000 0.000 0.000 0.0444 0.090 0.001 0.000 0.025 0.0889 0.090 0.002 0.000 0.025 0.1333 0.090 0.004 0.000 0.025 0.1778 0.090 0.005 0.000 0.025 0.2222 0.090 0.007 0.000 0.025 0.2667 0.090 0.008 0.000 0.025 0.3111 0.090 0.009 0.000 0.025 0.3556 0.090 0.011 0.000 0.025 0.4000 0.090 0.012 0.000 0.025 0.4444 0.090 0.014 0.000 0.025 0.4889 0.090 0.015 0.000 0.025 0.5333 0.090 0.016 0.000 0.025 0.5778 0.090 0.018 0.000 0.025 0.6222 0.090 0.019 0.000 0.025 0.6667 0.090 0.021 0.000 0.025 0.7111 0.090 0.022 0.000 0.025 0.7556 0.090 0.023 0.000 0.025 0.8000 0.090 0.025 0.000 0.025 0.8444 0.090 0.026 0.000 0.025 0.8889 0.090 0.028 0.000 0.025 0.9333 0.090 0.029 0.000 0.025 0.9778 0.090 0.031 0.000 0.025 1.0222 0.090 0.032 0.000 0.025 1.0667 0.090 0.033 0.000 0.025 1.1111 0.090 0.035 0.000 0.025 1.1556 0.090 0.036 0.000 0.025 1.2000 0.090 0.038 0.000 0.025 1.2444 0.090 0.039 0.000 0.025 1.2889 0.090 0.040 0.000 0.025 1.3333 0.090 0.042 0.000 0.025 1.3778 0.090 0.043 0.000 0.025 1.4222 0.090 0.045 0.000 0.025 1.4667 0.090 0.046 0.000 0.025 1.5111 0.090 0.047 0.000 0.025 1.5556 0.090 0.049 0.000 0.025 1.6000 0.090 0.050 0.000 0.025 1.6444 0.090 0.052 0.000 0.025 1.6889 0.090 0.053 0.000 0.025 1.7333 0.090 0.054 0.000 0.025 1.7778 0.090 0.056 0.000 0.025 1.8222 0.090 0.057 0.000 0.025 1.8667 0.090 0.059 0.000 0.025 1.9111 0.090 0.060 0.000 0.025 1.9556 0.090 0.062 0.000 0.025 2.0000 0.090 0.063 0.000 0.025 2.0444 0.090 0.064 0.000 0.025 2.0889 0.090 0.066 0.000 0.025 2.1333 0.090 0.067 0.000 0.025 2.1778 0.090 0.069 0.000 0.025 2.2222 0.090 0.070 0.000 0.025 2.2667 0.090 0.071 0.000 0.025 2.3111 0.090 0.073 0.000 0.025 2.3556 0.090 0.074 0.000 0.025 2.4000 0.090 0.076 0.000 0.025 2.4444 0.090 0.077 0.000 0.025 2.4889 0.090 0.078 0.000 0.025 2.5333 0.090 0.080 0.000 0.025 2.5778 0.090 0.081 0.000 0.025 2.6222 0.090 0.083 0.000 0.025 2.6667 0.090 0.084 0.000 0.025 2.7111 0.090 0.085 0.000 0.025 2.7556 0.090 0.087 0.000 0.025 2.8000 0.090 0.088 0.000 0.025 2.8444 0.090 0.090 0.000 0.025 2.8889 0.090 0.091 0.000 0.025 2.9333 0.090 0.093 0.000 0.025 2.9778 0.090 0.094 0.000 0.025 3.0222 0.090 0.095 0.000 0.025 Infilt(cfs) RAM F_ngineering, Inc. RAM No. 21-001 Page 4 ggrh Ave W Short Plat Updated Stormwater Modeling 3.0667 0.090 0.097 0.000 0.025 3.1111 0.090 0.098 0.000 0.025 3.1556 0.090 0.100 0.000 0.025 3.2000 0.090 0.101 0.000 0.025 3.2444 0.090 0.102 0.000 0.025 3.2889 0.090 0.104 0.000 0.025 3.3333 0.090 0.105 0.000 0.025 3.3778 0.090 0.107 0.000 0.025 3.4222 0.090 0.108 0.000 0.025 3.4667 0.090 0.109 0.000 0.025 3.5111 0.090 0.111 0.000 0.025 3.5556 0.090 0.112 0.000 0.025 3.6000 0.090 0.114 0.000 0.025 3.6444 0.090 0.115 0.000 0.025 3.6889 0.090 0.116 0.000 0.025 3.7333 0.090 0.118 0.000 0.025 3.7778 0.090 0.119 0.000 0.025 3.8222 0.090 0.121 0.000 0.025 3.8667 0.090 0.122 0.000 0.025 3.9111 0.090 0.123 0.000 0.025 3.9556 0.090 0.125 0.000 0.025 4.0000 0.090 0.126 0.000 0.025 RAM F_ngineering, Inc. RAM No. 21-001 Page 5 881n Ave W Short Plat Updated Stormwater Modeling ANALYSIS RESULTS Stream Protection Duration Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.96 Total Impervious Area:O Mitigated Landuse Totals for POC #1 Total Pervious Area:0.67 Total Impervious Area:0.29 2 year 0.01629 5 year 0.025281 10 year 0.030159 25 year 0.03512 50 year 0.038066 100 year 0.040488 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 ® Analysis 1.0 Cumulative Probability 91 x xxxxxx x �w�ykooe000� 0.1 0.1 x x x x xxx� r H+++ + Wl o <L x 701 0.01 --- - - • 801 0.001 0.001 0 0.5 1 2 5 10 20 30 50 70 80 90 95 98 9999.5100 Stream Protection Duration LID Duration Flow Frequency I Water Quality I Hydrograph Welland Input Volumes I LIDReport Recharge Duration I RechargePredeveloped I Recharge Mitigated Analyze datasets Compact WDM I Delete Selected r MW* FF 501 POC 1 Redeveloped How 701 Inflow to POC 1 Mitigated :0r POC 1 ad 1000 Gravel Trench Bed 1 ALL OUTLETS Mitigated 1001 Gravel Trench Bed 1 OUTLET 1 Mitigated 1002 Gravel Trench Bed 1 OUTLET 2 Mitigated AODatasets Flow IStage I Necip Evap POC1 Flood Frequency McOrod r Log Pearson Type III 17B t Weibull C Cunnane (" Gr'rgaten Flow Frequency Flow(cfs) 0501 15m 0701 15m 0801 15m 2 Year = 0.0163 0.0966 0.0000 5 Year = 0.0253 0.1322 0.0000 10 Year = 0.0302 0.1591 0.0000 25 Year = 0.0351 0.1969 0.0000 50 Year = 0.0381 0.2281 0.0000 100 Year = 0.0405 0.2620 0.0000 Annual Peaks 1902 0.0227 0.1050 0.0000 1903 0.0079 0.1142 0.0000 1904 0.0146 0.1410 0.0000 1905 0.0092 0.0635 0.0000 1906 0.0037 0.0713 0.0000 1907 0.0254 0.0989 0.0000 1908 0.0161 0.0806 0.0000 1909 0.0175 0.0947 0.0000 1910 0.0277 0.1019 0.0000 1911 0.0145 0.0982 0.0000 1912 0.0492 0.2276 0.0000 1913 0.0244 0.0701 0.0000 1914 0.0057 0.2629 0.0000 1915 0.0083 0.0631 0.0000 1916 0.0132 0.1133 0.0000 1917 0.0064 0.0579 0.0000 1918 0.0156 0.0884 0.0000 1919 0.0116 0.0570 0.0000 1920 0.0149 0.0844 0.0000 1921 0.0158 0.0695 0.0000 1922 0.0179 0.0969 0.0000 1923 0.0117 0.0813 0.0000 1924 0.0078 0.1248 0.0000 1925 0.0079 0.0586 0.0000 1926 0.0142 0.1123 0.0000 1927 0.0183 0.0879 0.0000 1928 0.0120 0.0768 0.0000 1929 0.0257 0.1203 0.0000 RAMEngineering, Inc. RAM No. 21-001 Page 6 ggrn Ave W Short Plat Updated Stormwater Modeling Stream Protection Duration Annual Peaks for Predeveloped and Mitigated Year Predeveloped Mitigated 1902 0.023 0.000 1903 0.008 0.000 1904 0.015 0.000 1905 0.009 0.000 1906 0.004 0.000 1907 0.025 0.000 1908 0.016 0.000 1909 0.018 0.000 1910 0.028 0.000 1911 0.014 0.000 1912 0.049 0.000 1913 0.024 0.000 1914 0.006 0.000 1915 0.008 0.000 1916 0.013 0.000 1917 0.006 0.000 1918 0.016 0.000 1919 0.012 0.000 1920 0.015 0.000 1921 0.016 0.000 1922 0.018 0.000 1923 0.012 0.000 1924 0.008 0.000 1925 0.008 0.000 1926 0.014 0.000 1927 0.018 0.000 1928 0.012 0.000 1929 0.026 0.000 1930 0.015 0.000 1931 0.015 0.000 1932 0.011 0.000 1933 0.013 0.000 1934 0.036 0.000 1935 0.013 0.000 1936 0.021 0.000 1937 0.017 0.000 1938 0.018 0.000 1939 0.001 0.000 1940 0.014 0.000 1941 0.014 0.000 1942 0.021 0.000 1943 0.007 0.000 1944 0.018 0.000 1945 0.016 0.000 1946 0.014 0.000 1947 0.010 0.000 1948 0.033 0.000 1949 0.027 0.000 1950 0.015 0.000 1951 0.017 0.000 1952 0.048 0.000 1953 0.042 0.000 1954 0.013 0.000 1955 0.011 0.000 1956 0.008 0.000 1957 0.019 0.000 1958 0.045 0.000 1959 0.027 0.000 1960 0.010 0.000 1961 0.028 0.000 1962 0.014 0.000 1963 0.007 0.000 1964 0.013 0.000 1965 0.033 0.000 1966 0.006 0.000 1967 0.013 0.000 1968 0.017 0.000 1969 0.012 0.000 POC #1 RAM F_ngineering, Inc. RAM No. 21-001 Page 7 ggrh Ave W Short Plat Updated Stormwater Modeling 1970 0.019 0.000 1971 0.035 0.000 1972 0.023 0.000 1973 0.026 0.000 1974 0.015 0.000 1975 0.037 0.000 1976 0.017 0.000 1977 0.010 0.000 1978 0.032 0.000 1979 0.009 0.000 1980 0.016 0.000 1981 0.016 0.000 1982 0.011 0.000 1983 0.026 0.000 1984 0.007 0.000 1985 0.016 0.000 1986 0.012 0.000 1987 0.026 0.000 1988 0.020 0.000 1989 0.015 0.000 1990 0.020 0.000 1991 0.015 0.000 1992 0.023 0.000 1993 0.019 0.000 1994 0.033 0.000 1995 0.008 0.000 1996 0.037 0.000 1997 0.017 0.000 1998 0.016 0.000 1999 0.001 0.000 2000 0.012 0.000 2001 0.009 0.000 2002 0.023 0.000 2003 0.018 0.000 2004 0.018 0.000 2005 0.022 0.000 2006 0.012 0.000 2007 0.013 0.000 2008 0.017 0.000 2009 0.011 0.000 2010 0.008 0.000 2011 0.011 0.000 2012 0.015 0.000 2013 0.012 0.000 2014 0.008 0.000 2015 0.032 0.000 2016 0.004 0.000 2017 0.026 0.000 2018 0.045 0.000 2019 0.049 0.000 2020 0.014 0.000 2021 0.022 0.000 2022 0.008 0.000 2023 0.018 0.000 2024 0.038 0.000 2025 0.014 0.000 2026 0.025 0.000 2027 0.011 0.000 2028 0.005 0.000 2029 0.018 0.000 2030 0.035 0.000 2031 0.010 0.000 2032 0.008 0.000 2033 0.009 0.000 2034 0.010 0.000 2035 0.040 0.000 2036 0.021 0.000 2037 0.004 0.000 2038 0.020 0.000 2039 0.002 0.000 2040 0.007 0.000 RAM F_ngineering, Inc. RAM No. 21-001 Page 8 ggrh Ave W Short Plat Updated Stormwater Modeling 2041 0.011 0.000 2042 0.041 0.000 2043 0.018 0.000 2044 0.025 0.000 2045 0.016 0.000 2046 0.019 0.000 2047 0.012 0.000 2048 0.016 0.000 2049 0.015 0.000 2050 0.010 0.000 2051 0.016 0.000 2052 0.009 0.000 2053 0.017 0.000 2054 0.022 0.000 2055 0.007 0.000 2056 0.006 0.000 2057 0.011 0.000 2058 0.013 0.000 Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0493 0.0000 2 0.0492 0.0000 3 0.0478 0.0000 4 0.0452 0.0000 5 0.0446 0.0000 6 0.0424 0.0000 7 0.0412 0.0000 8 0.0396 0.0000 9 0.0383 0.0000 10 0.0373 0.0000 11 0.0369 0.0000 12 0.0358 0.0000 13 0.0352 0.0000 14 0.0349 0.0000 15 0.0333 0.0000 16 0.0332 0.0000 17 0.0328 0.0000 18 0.0323 0.0000 19 0.0322 0.0000 20 0.0278 0.0000 21 0.0277 0.0000 22 0.0274 0.0000 23 0.0272 0.0000 24 0.0264 0.0000 25 0.0263 0.0000 26 0.0262 0.0000 27 0.0260 0.0000 28 0.0257 0.0000 29 0.0254 0.0000 30 0.0251 0.0000 31 0.0250 0.0000 32 0.0244 0.0000 33 0.0229 0.0000 34 0.0228 0.0000 35 0.0227 0.0000 36 0.0227 0.0000 37 0.0224 0.0000 38 0.0220 0.0000 39 0.0219 0.0000 40 0.0213 0.0000 41 0.0212 0.0000 42 0.0205 0.0000 43 0.0204 0.0000 44 0.0200 0.0000 45 0.0196 0.0000 46 0.0189 0.0000 47 0.0187 0.0000 RAM F_ngineering, Inc. RAM No. 21-001 Page 9 ggrh Ave W Short Plat Updated Stormwater Modeling 48 0.0185 0.0000 49 0.0185 0.0000 50 0.0183 0.0000 51 0.0183 0.0000 52 0.0180 0.0000 53 0.0180 0.0000 54 0.0179 0.0000 55 0.0179 0.0000 56 0.0177 0.0000 57 0.0177 0.0000 58 0.0176 0.0000 59 0.0175 0.0000 60 0.0175 0.0000 61 0.0175 0.0000 62 0.0173 0.0000 63 0.0172 0.0000 64 0.0168 0.0000 65 0.0166 0.0000 66 0.0165 0.0000 67 0.0165 0.0000 68 0.0163 0.0000 69 0.0161 0.0000 70 0.0160 0.0000 71 0.0158 0.0000 72 0.0158 0.0000 73 0.0158 0.0000 74 0.0158 0.0000 75 0.0156 0.0000 76 0.0156 0.0000 77 0.0156 0.0000 78 0.0154 0.0000 79 0.0153 0.0000 80 0.0152 0.0000 81 0.0149 0.0000 82 0.0148 0.0000 83 0.0148 0.0000 84 0.0148 0.0000 85 0.0147 0.0000 86 0.0147 0.0000 87 0.0146 0.0000 88 0.0145 0.0000 89 0.0144 0.0000 90 0.0144 0.0000 91 0.0143 0.0000 92 0.0142 0.0000 93 0.0142 0.0000 94 0.0141 0.0000 95 0.0140 0.0000 96 0.0134 0.0000 97 0.0132 0.0000 98 0.0132 0.0000 99 0.0132 0.0000 100 0.0129 0.0000 101 0.0129 0.0000 102 0.0128 0.0000 103 0.0128 0.0000 104 0.0124 0.0000 105 0.0123 0.0000 106 0.0122 0.0000 107 0.0120 0.0000 108 0.0117 0.0000 109 0.0117 0.0000 110 0.0116 0.0000 ill 0.0116 0.0000 112 0.0116 0.0000 113 0.0115 0.0000 114 0.0114 0.0000 115 0.0110 0.0000 116 0.0109 0.0000 117 0.0109 0.0000 118 0.0108 0.0000 RAM F_ngineering, Inc. RAM No. 21-001 Page 10 ggrn Ave W Short Plat Updated Stormwater Modeling 119 0.0106 0.0000 120 0.0106 0.0000 121 0.0104 0.0000 122 0.0100 0.0000 123 0.0098 0.0000 124 0.0098 0.0000 125 0.0098 0.0000 126 0.0096 0.0000 127 0.0094 0.0000 128 0.0092 0.0000 129 0.0089 0.0000 130 0.0088 0.0000 131 0.0086 0.0000 132 0.0085 0.0000 133 0.0083 0.0000 134 0.0082 0.0000 135 0.0079 0.0000 136 0.0079 0.0000 137 0.0079 0.0000 138 0.0078 0.0000 139 0.0078 0.0000 140 0.0078 0.0000 141 0.0076 0.0000 142 0.0074 0.0000 143 0.0072 0.0000 144 0.0069 0.0000 145 0.0068 0.0000 146 0.0066 0.0000 147 0.0064 0.0000 148 0.0063 0.0000 149 0.0059 0.0000 150 0.0057 0.0000 151 0.0054 0.0000 152 0.0045 0.0000 153 0.0039 0.0000 154 0.0037 0.0000 155 0.0018 0.0000 156 0.0011 0.0000 157 0.0008 0.0000 RAM F_ngineering, Inc. RAM No. 21-001 Page 11 881n Ave W Short Plat Updated Stormwater Modeling Stream Protection Duration POC #1 The Facility PASSED O J Percent Time Exceeding Stream Protection Duration LID Duration I Flow Frequency I Water Quality Hydrograph I Wetland Input Volumes LIDRepol RechargeDural'an RechargePredeveloped I Recharge Mitigated Analyze dalasets Compact WDM I Delete Selected r M"" FF F-7E AEDatasets I Flow I Stage I Precip I Evap PDC1 Flood Frequency Method f• Log Pearson Type III 178 [ Weibull Cunnane f Gringorten The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0081 53267 0 0 Pass 0.0084 49006 0 0 Pass 0.0087 45136 0 0 Pass 0.0091 41761 0 0 Pass 0.0094 38645 0 0 Pass 0.0097 35805 0 0 Pass 0.0100 33228 0 0 Pass 0.0103 30916 0 0 Pass 0.0106 28879 0 0 Pass 0.0109 26964 0 0 Pass 0.0112 25202 0 0 Pass 0.0115 23473 0 0 Pass 0.0118 21871 0 0 Pass 0.0121 20347 0 0 Pass 0.0124 18943 0 0 Pass 0.0127 17693 0 0 Pass 0.0130 16493 0 0 Pass 0.0133 15469 0 0 Pass 0.0136 14473 0 0 Pass 0.0139 13520 0 0 Pass 0.0142 12629 0 0 Pass 0.0145 11792 0 0 Pass 0.0148 11065 0 0 Pass 0.0151 10427 0 0 Pass 0.0154 9848 0 0 Pass 0.0157 9309 0 0 Pass 0.0160 8786 0 0 Pass 0.0163 8296 0 0 Pass 0.0166 7850 0 0 Pass C I The Facility PASSED ow(cfs) Predev Mit Percentage Pass/Fail 0081 53267 0 0 Pass 0084 49006 0 0 Pass 0087 45136 0 0 Pass 0091 41761 0 0 Pass 0094 38645 0 0 Pass 0097 35805 0 0 Pass 0100 33228 0 0 Pass 0103 30916 0 0 Pass 0106 28879 0 0 Pass 0109 26964 0 0 Pass 0112 25202 0 0 Pass 0115 23473 0 0 Pass 0118 21871 0 0 Pass 0121 20347 0 0 Pass 0124 18943 0 0 Pass 0127 17693 0 0 Pass 0130 16493 0 0 Pass 0133 15469 0 0 Pass 0136 14473 0 0 Pass 0139 13520 0 0 Pass 0142 12629 0 0 Pass 0145 11792 0 0 Pass 0148 11065 0 0 Pass 0151 10427 0 0 Pass 0154 9848 0 0 Pass 0157 9309 0 0 Pass 0160 8786 0 0 Pass 0163 8296 0 0 Pass 0166 7850 0 0 Pass 0169 7415 0 0 Pass 0172 7035 0 0 Pass 0175 6667 0 0 Pass 0178 6353 0 0 Pass 0181 6045 0 0 Pass RAM 4Fngineering, Inc. RAM No. 21-001 Page 12 881h Ave W Short Plat Updated Stormwater Modeling 0.0169 7415 0 0 Pass 0.0172 7035 0 0 Pass 0.0175 6667 0 0 Pass 0.0178 6353 0 0 Pass 0.0181 6045 0 0 Pass 0.0184 5742 0 0 Pass 0.0187 5474 0 0 Pass 0.0190 5222 0 0 Pass 0.0193 4993 0 0 Pass 0.0196 4763 0 0 Pass 0.0199 4538 0 0 Pass 0.0202 4335 0 0 Pass 0.0205 4128 0 0 Pass 0.0208 3943 0 0 Pass 0.0211 3772 0 0 Pass 0.0214 3631 0 0 Pass 0.0217 3495 0 0 Pass 0.0220 3369 0 0 Pass 0.0223 3258 0 0 Pass 0.0227 3145 0 0 Pass 0.0230 3054 0 0 Pass 0.0233 2966 0 0 Pass 0.0236 2877 0 0 Pass 0.0239 2779 0 0 Pass 0.0242 2681 0 0 Pass 0.0245 2587 0 0 Pass 0.0248 2493 0 0 Pass 0.0251 2387 0 0 Pass 0.0254 2278 0 0 Pass 0.0257 2181 0 0 Pass 0.0260 2080 0 0 Pass 0.0263 1999 0 0 Pass 0.0266 1927 0 0 Pass 0.0269 1866 0 0 Pass 0.0272 1790 0 0 Pass 0.0275 1719 0 0 Pass 0.0278 1663 0 0 Pass 0.0281 1595 0 0 Pass 0.0284 1537 0 0 Pass 0.0287 1482 0 0 Pass 0.0290 1420 0 0 Pass 0.0293 1360 0 0 Pass 0.0296 1298 0 0 Pass 0.0299 1242 0 0 Pass 0.0302 1188 0 0 Pass 0.0305 1146 0 0 Pass 0.0308 1100 0 0 Pass 0.0311 1045 0 0 Pass 0.0314 1000 0 0 Pass 0.0317 954 0 0 Pass 0.0320 916 0 0 Pass 0.0323 877 0 0 Pass 0.0326 832 0 0 Pass 0.0329 788 0 0 Pass 0.0332 754 0 0 Pass 0.0335 710 0 0 Pass 0.0338 666 0 0 Pass 0.0341 627 0 0 Pass 0.0344 595 0 0 Pass 0.0347 554 0 0 Pass 0.0350 516 0 0 Pass 0.0353 461 0 0 Pass 0.0356 423 0 0 Pass 0.0360 392 0 0 Pass 0.0363 360 0 0 Pass 0.0366 334 0 0 Pass 0.0369 306 0 0 Pass 0.0372 286 0 0 Pass 0.0375 264 0 0 Pass 0.0378 247 0 0 Pass 0.0381 233 0 0 Pass RAM F_ngineering, Inc. RAM No. 21-001 Page 13 ggrh Ave W Short Plat Updated Stormwater Modeling 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. LID Report Cumulative Percent Water Quality Percent Comment Volume Volume Water Quality Infiltration Infiltrated Treated Credit p 100.00 10 100.00 0.00 0% No Treat Credit Duration Analysis Result = Passed Perind and Impind Changes No changes have been made. 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. 2005-2022; All Rights Reserved. RAM F_ngineering, Inc. RAM No. 21-001 Page 14 ggrh Ave W Short Plat Updated Stormwater Modeling