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Approved Stormwater Report.pdfCATEGORY f s SHEPROJEcr DANIM46EREPORT for NEED ./OHNSONSHORTPLAT 8498 Talbot Road Edmonds, WA 98026 CSP Engineering PFN 16-002 City of Edmonds PLN20170020 03-28-19 b3 9 COMPLIES WITH APPLICABLE CITY S 11 ATER r-pD F Da e:_ csp EA►gineen"a Civil Engineering Design and Consufting 1037 NE 651h St # 153 Seattle, WA 98115 Phase: 206 406 9965 email@cspengineering.com www.cspengineenng.com RECEIVED APR 012019 DEVELOPMENT SERVICES COUNTER Project Overview One single family residence is proposed in conjunction with a 2-lot short plat of a 0.92 acre Site Parcel situated in the Perrinville Creek Drainage Basin/Puget Sound Watershed. Impervious and permeable hardscape surface for the built - out project is estimated to be 3,899 sf and will be comprised of NPGIS roof area, PGIS driveway and road frontage asphalt pavement, and a PGPS driveway apron. The proposed improvements will disturb —0.25 acres. The project soils report indicates that onsite infiltration is feasible. The project is not anticipated to create greater than 5,000 sf of impervious surface and will disturb less than 1.0 acre in land and is therefore classified as a Category 1 Small Site Project and is subject to Minimum Requirements 1 through 5. Impervious Surface Summary j Future House 2,217 sf Future Onsite Driveway 727 sf _ Future Driveway apron 338 sf Roadway Widening 617 sf Total 3,899 sf Note: Infiltration trench sized for 5,000 sf of Impervious Surface . Small Site Minimum Requirement #1— Preparation of Stormwater Site Plan This report combined with the Civil Plans address this requirement. Small Site Minimum Requirement #2 — Construction Stormwater Pollution Prevention Plan This report combined with the Civil Plans address this requirement. Small Site Minimum Requirement #3 — Source Control of Pollution Specific source controls are not required for single family residential sites. Small Site Minimum Requirement #4 — Preservation of Natural Drainage Systems and Outfalls Topography of the Site Parcel and surrounding areas direct stormwater in a westerly direction via sheetflow. Upstream and downstream areas are developed with low density single family residences. No surface drainage features were surveyed either entering or exiting the Site Parcel. The proposed development will not alter the existing natural drainage patterns. All proposed impervious surfaces will be infiltrated on site therefore a downstream analysis is not warranted. Small Site Minimum Requirement #5 — Onsite Stormwater Management List #1 Analysis: Lawn and Landscaped Areas- BMP T5.13 Post -Construction Soil Amendment Roof Areas - Full Infiltration Other Hard Surfaces - Full Infiltration is proposed for asphalt areas in lieu of Full Dispersion; Permeable Pavement is proposed for the driveway apron. Onsite Full Infiltration is based on Nelson Geotechnical Associates Inc. 02-02-18 Stormwater Infiltration Letter that delineates a long-term infiltration rate of 10.00 inches per hour. WWHM2012 calculations indicate that an infiltration trench of 35'x3'x2' deep will infiltrate 100% of the stormwater generated by 5,000 sf of Impervious Surface. Due to site topography a portion of the Impervious Surface associated with road improvements along Frederick Place will bypass the infiltration system however the proposed system anticipates accommodating this area in lieu of direct mitigation. Appendix d 6Sth St S% Outfall CreekStilthOU-5e Creel( Terrace Creek 0 11000 21000 Ow 61000 MM!9iiiiiiiaFeet I In = 2,000 ft PROJECT SITE Perrinville PLII',Ct Sound Talbot Park A Talbbt Park R Vicinity/Basin Map 0 1,000 2.000 4.000 6.000 I In m 2.000 ft 6,000 R Feet Soils Map Slope Map b Soil Map —Snohomish County Area, Washington 3: 470 50 34' N 47" 5017N 548540 Sim 540740 549790 548M 54M 548M 3 b �j Map Scale: 1:2,230 If prV*Bd cn A porb (8.5" x 11") glee .Mears N y� 0 30 BD ,20 1f,0 p A D 0 100 200 40D fi00 Map pro)edbn: Web Mermtor Caner oomdhahrs: V4GS84 Edge tla: UTM Zone ION %A 5 i wm Natural Resources Web Soil Survey 1/26/2017 --1r Conservation Service National Cooperative Soil Survey Page 1 of 3 47" 50 34' N 47" 501T N CT REPORT General Model Information Project Name: 16-002 Reed Johnson 2019-03-28 Site Name: Reed Johnson Short Plat Site Address: 8409 Talbot Road City: Edmonds Report Date: 3/28/2019 Gage: Everett Data Start: 1948/10/01 Data End: 2009/09/30 Timestep: 15 Minute Precip Scale: 0.800 Version Date: 2018/10/10 Version: 4.2.16 POC Thresholds Low Flow Threshold for POC1: High Flow Threshold for POC1: 50 Percent of the 2 Year 50 Year 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:05 PM Page 2 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Mod 0.11 Pervious Total 0.11 Impervious Land Use acre Impervious Total 0 Basin Total 0.11 Element Flows To: Surface Interflow G r 16-002 Reed Johnson 2019-03-28 3/28/20h9 2:24:05 PM Page 3 Mitigated Land Use Basin 1 Bypass: No GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 0.05 DRIVEWAYS MOD 0.06 Impervious Total 0.11 Basin Total 0.11 Element Flows To: Surface Interflow Grou Gravel Trench Bed 1 Gravel Trench Bed 1 ndwater 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:05 PM Page 4 Routing Elements Predeveloped Routing 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:05 PM Page 5 Mitigated Routing Gravel Trench Bed 1 Bottom Length: 35.00 ft. Bottom Width: 3.00 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: 2 Pour Space of material for first layer: 0.3 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: 10 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 12.701 Total Volume Through Riser (ac-ft.): 0.014 Total Volume Through Facility (ac-ft.): 12.715 Percent Infiltrated: 99.89 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 2 ft. Riser Diameter: 6 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.002 0.000 0.000 0.000 0.0333 0.002 0.000 0.000 0.024 0.0667 0.002 0.000 0.000 0.024 0.1000 0.002 0.000 0.000 0.024 0.1333 0.002 0.000 0.000 0.024 0.1667 0.002 0.000 0.000 0.024 0.2000 0.002 0.000 0.000 0.024 0.2333 0.002 0.000 0.000 0.024 0.2667 0.002 0.000 0.000 0.024 0.3000 0.002 0.000 0.000 0.024 0.3333 0.002 0.000 0.000 0.024 0.3667 0.002 0.000 0.000 0.024 0.4000 0.002 0.000 0.000 0.024 0.4333 0.002 0.000 0.000 0.024 0.4667 0.002 0.000 0.000 0.024 0.5000 0.002 0.000 0.000 0.024 0.5333 0.002 0.000 0.000 0.024 0.5667 0.002 0.000 0.000 0.024 0.6000 0.002 0.000 0.000 0.024 0.6333 0.002 0.000 0.000 0.024 0.6667 0.002 0.000 0.000 0.024 0.7000 0.002 0.000 0.000 0.024 0.7333 0.002 0.000 0.000 0.024 0.7667 0.002 0.000 0.000 0.024 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24 05 PM Page 6 0.8000 0.002 0.000 0.000 0.024 0.8333 0.002 0.000 0.000 0.024 0.8667 0.002 0.000 0.000 0.024 0.9000 0.002 0.000 0.000 0.024 0.9333 0.002 0.000 0.000 0.024 0.9667 0.002 0.000 0.000 0.024 1.0000 0.002 0.000 0.000 0.024 1.0333 0.002 0.000 0.000 0.024 1.0667 0.002 0.000 0.000 0.024 1.1000 0.002 0.000 0.000 0.024 1.1333 0.002 0.000 0.000 0.024 1.1667 0.002 0.000 0.000 0.024 1.2000 0.002 0.000 0.000 0.024 1.2333 0.002 0.000 0.000 0.024 1.2667 0.002 0.000 0.000 0.024 1.3000 0.002 0.000 0.000 0.024 1.3333 0.002 0.001 0.000 0.024 1.3667 0.002 0.001 0.000 0.024 1.4000 0.002 0.001 0.000 0.024 1.4333 0.002 0.001 0.000 0.024 1.4667 0.002 0.001 0.000 0.024 1.5000 0.002 0.001 0.000 0.024 1.5333 0.002 0.001 0.000 0.024 1.5667 0.002 0.001 0.000 0.024 1.6000 0.002 0.001 0.000 0.024 1.6333 0.002 0.001 0.000 0.024 1.6667 0.002 0.001 0.000 0.024 1.7000 0.002 0.001 0.000 0.024 1.7333 0.002 0.001 0.000 0.024 1.7667 0.002 0.001 0.000 0.024 1.8000 0.002 0.001 0.000 0.024 1.8333 0.002 0.001 0.000 0.024 1.8667 0.002 0.001 0.000 0.024 1.9000 0.002 0.001 0.000 0.024 1.9333 0.002 0.001 0.000 0.024 1.9667 0.002 0.001 0.000 0.024 2.0000 0.002 0.001 0.000 0.024 2.0333 0.002 0.001 0.032 0.024 2.0667 0.002 0.001 0.090 0.024 2.1000 0.002 0.001 0.160 0.024 2.1333 0.002 0.001 0.233 0.024 2.1667 0.002 0.001 0.297 0.024 2.2000 0.002 0.002 0.346 0.024 2,2333 0.002 0.002 0.378 0.024 2.2667 0.002 0.002 0.406 0.024 2.3000 0.002 0.002 0.431 0.024 2.3333 0.002 0.002 0.454 0.024 2.3667 0.002 0.002 0.476 0.024 2.4000 0.002 0.002 0.498 0.024 2.4333 0.002 0.002 0.518 0.024 2.4667 0.002 0.002 0.537 0.024 2.5000 0.002 0.002 0.556 0.024 2.5333 0.002 0.002 0.575 0.024 2.5667 0.002 0.002 0.592 0.024 2.6000 0.002 0.002 0.609 0.024 2.6333 0.002 0.003 0.626 0.024 2.6667 0.002 0.003 0.642 0.024 2.7000 0.002 0.003 0.658 0.024 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:05 PM Page 7 2.7333 0.002 0.003 0.674 0.024 2.7667 0.002 0.003 0.689 0.024 2.8000 0.002 0.003 0.704 0.024 2.8333 0.002 0.003 0.718 0.024 2.8667 0.002 0.003 0.733 0.024 2.9000 0.002 0.003 0.747 0.024 2.9333 0.002 0.003 0.760 0.024 2.9667 0.002 0.003 0.774 0.024 3.0000 0.002 0.003 0.787 0.024 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:05 PM Page 8 Analysis Results POC 1 t b 000 u 0 0 00 IL 000 u. ., 10E4 ._. 10E-2 10E-1 t 10 100 Percent Time Exceeding + Predeveloped Predeveloped Landuse Totals for POC #1 Total Pervious Area: 0.11 Total Impervious Area: 0 Mitigated Landuse Totals for POC #1 Total Pervious Area: 0 Total Impervious Area: 0.11 m 0 0l o Dot 14 OS 1 t x Mitigated Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.001354 5 year 0.002118 10 year 0.002594 25 year 0.003148 50 year 0.003526 100 year 0.003875 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 0.000 1950 0.002 0.000 1951 0.001 0.000 1952 0.001 0.000 1953 0.001 0.000 1954 0.002 0.002 1955 0.002 0.000 1956 0.002 0.000 1957 0.002 0.000 1958 0.001 0.023 Cumulative Prohab44y ME 5W$ 3 to A 7) so To so % % % 03 1 16-002 Reed Johnson 2019-03-28 3/28/2019 2 24 05 PM Page 9 1959 0.001 0.000 1960 0.001 0.000 1961 0.001 0.081 1962 0.001 0.000 1963 0.001 0.001 1964 0.001 0.000 1965 0.001 0.000 1966 0.001 0.000 1967 0.002 0.053 1968 0.002 0.000 1969 0.001 0.015 1970 0.001 0.000 1971 0.002 0.000 1972 0.001 0.027 1973 0.001 0.000 1974 0.002 0.000 1975 0.001 0.000 1976 0.001 0.000 1977 0.000 0.000 1978 0.001 0.000 1979 0.002 0.004 1980 0.001 0.000 1981 0.001 0.000 1982 0.001 0.000 1983 0.001 0.000 1984 0.001 0.000 1985 0.002 0.000 1986 0.005 0.000 1987 0.002 0.000 1988 0.001 0.000 1989 0.001 0.000 1990 0.001 0.000 1991 0.002 0.000 1992 0.001 0.000 1993 0.001 0.000 1994 0.000 0.000 1995 0.001 0.000 1996 0.003 0.000 1997 0.006 0.000 1998 0.001 0.013 1999 0.001 0.000 2000 0.001 0.018 2001 0.000 0.000 2002 0.001 0.000 2003 0.001 0.000 2004 0.001 0.020 2005 0.001 0.000 2006 0.003 0.000 2007 0.002 0.000 2008 0.003 0.000 2009 0.001 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0056 0.0809 2 0.0051 0.0533 3 0.0031 0.0269 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:37 PM Page 10 4 0.0031 0.0230 5 0.0030 0.0198 6 0.0023 0.0180 7 0.0023 0.0151 8 0.0023 0.0127 9 0.0021 0.0039 10 0.0020 0.0024 11 0.0020 0.0014 12 0.0019 0.0000 13 0.0019 0.0000 14 0.0019 0.0000 15 0.0017 0.0000 16 0.0017 0.0000 17 0.0016 0.0000 18 0.0016 0.0000 19 0.0015 0.0000 20 0.0015 0.0000 21 0.0015 0.0000 22 0.0015 0.0000 23 0.0015 0.0000 24 0.0014 0.0000 25 0.0014 0.0000 26 0.0014 0.0000 27 0.0014 0.0000 28 0.0014 0.0000 29 0.0014 0.0000 30 0.0013 0.0000 31 0.0013 0.0000 32 0.0013 0.0000 33 0.0013 0.0000 34 0.0013 0.0000 35 0.0013 0.0000 36 0.0012 0.0000 37 0.0011 0.0000 38 0.0011 0.0000 39 0.0011 0.0000 40 0.0011 0.0000 41 0.0011 0.0000 42 0.0011 0.0000 43 0.0011 0.0000 44 0.0010 0.0000 45 0.0010 0.0000 46 0.0010 0.0000 47 0.0010 0.0000 48 0.0009 0.0000 49 0.0009 0.0000 50 0.0009 0.0000 51 0.0008 0.0000 52 0.0008 0.0000 53 0.0008 0.0000 54 0.0008 0.0000 55 0.0008 0.0000 56 0.0007 0.0000 57 0.0007 0.0000 58 0.0005 0.0000 59 0.0005 0.0000 60 0.0002 0.0000 61 0.0002 0.0000 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:37 PM Page 11 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:37 PM Page 12 Duration Flows The Facility PASSED Flow(cfs) Predev Mit Percentage Pass/Fail 0.0007 21081 43 0 Pass 0.0007 19284 43 0 Pass 0.0007 17562 43 0 Pass 0.0008 15977 43 0 Pass 0.0008 14510 43 0 Pass 0.0008 13302 43 0 Pass 0.0008 12172 43 0 Pass 0.0009 11124 40 0 Pass 0.0009 10183 40 0 Pass 0.0009 9338 40 0 Pass 0.0010 8620 40 0 Pass 0.0010 7944 40 0 Pass 0.0010 7338 40 0 Pass 0.0011 6731 40 0 Pass 0.0011 6228 40 0 Pass 0.0011 5717 40 0 Pass 0.0011 5234 40 0 Pass 0.0012 4795 40 0 Pass 0.0012 4389 39 0 Pass 0.0012 4066 39 0 Pass 0.0013 3756 39 1 Pass 0.0013 3480 39 1 Pass 0.0013 3206 39 1 Pass 0.0013 2956 39 1 Pass 0.0014 2731 38 1 Pass 0.0014 2543 36 1 Pass 0.0014 2385 36 1 Pass 0.0015 2248 36 1 Pass 0.0015 2122 36 1 Pass 0.0015 2006 36 1 Pass 0.0015 1904 36 1 Pass 0.0016 1789 36 2 Pass 0.0016 1689 36 2 Pass 0.0016 1590 36 2 Pass 0.0017 1486 36 2 Pass 0.0017 1384 36 2 Pass 0.0017 1321 36 2 Pass 0.0017 1252 36 2 Pass 0.0018 1202 36 2 Pass 0.0018 1158 36 3 Pass 0.0018 1120 36 3 Pass 0.0019 1077 36 3 Pass 0.0019 1032 36 3 Pass 0.0019 993 36 3 Pass 0.0019 965 36 3 Pass 0.0020 928 36 3 Pass 0.0020 895 36 4 Pass 0.0020 858 36 4 Pass 0.0021 822 36 4 Pass 0.0021 791 36 4 Pass 0.0021 758 36 4 Pass 0.0021 732 36 4 Pass 0.0022 707 36 5 Pass 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:37 PM Page 13 0.0022 683 36 "5 Pass 0.0022 664 36 5 Pass 0.0023 645 36 5 Pass 0.0023 626 36 5 Pass 0.0023 607 36 5 Pass 0.0023 584 36 6 Pass 0.0024 567 36 6 Pass 0.0024 556 36 6 Pass 0.0024 541 34 6 Pass 0.0025 526 34 6 Pass 0.0025 515 34 6 Pass 0.0025 505 34 6 Pass 0.0025 495 34 6 Pass 0.0026 483 34 7 Pass 0.0026 471 34 7 Pass 0.0026 459 34 7 Pass 0.0027 443 34 7 Pass 0.0027 428 34 7 Pass 0.0027 417 34 8 Pass 0.0027 405 34 8 Pass 0.0028 388 34 8 Pass 0.0028 371 34 9 Pass 0.0028 355 34 9 Pass 0.0029 338 34 10 Pass 0.0029 325 34 10 Pass 0.0029 318 34 10 Pass 0.0030 307 34 11 Pass 0.0030 301 32 10 Pass 0.0030 291 32 10 Pass 0.0030 287 31 10 Pass 0.0031 279 31 11 Pass 0.0031 274 31 11 Pass 0.0031 268 31 11 Pass 0.0032 265 31 11 Pass 0.0032 262 31 11 Pass 0.0032 257 31 12 Pass 0.0032 253 31 12 Pass 0.0033 245 31 12 Pass 0.0033 242 31 12 Pass 0.0033 236 31 13 Pass 0.0034 231 31 13 Pass 0.0034 226 31 13 Pass 0.0034 224 31 13 Pass 0.0034 222 31 13 Pass 0.0035 220 31 14 Pass 0.0035 217 31 14 Pass 0.0035 211 31 14 Pass 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:37 PM Page 14 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. 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:37 PM Page 15 LID Report �[ChnIGUe Used forTotal Volume Voume InfiltAon Cu rrwtssrve PercM Wabf Quail/ Pemer4 comment �T, atment7 Needs Through Volume Volume Votume Water TtaaW*rd Faukty (ac-tt) Inti"on InWated Trwated ! (ac n (aOn credit aw: Trench Bed 1 POc t1 S7 tI9•ttD z' ' Blume lnbaa►.ed I 11.57 000 000 99.&9 0.00 0,4141 o Trl ai .ii.lpl;anct w10r UO ` t.Vrwys�•� o rrdard 8% o(2-yr In 50% ol � Rsaafl _ r� posed 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:37 PM Page 16 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. 1MPLND Changes No IMPLND changes have been made. 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:45 PM Page 17 Appendix Predeveloped Schematic L� Basin 0.11 ac E.1 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:45 PM Page 18 Mitigated Schematic Basin 1 SI Gravel a, Trench Bed 1 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:45 PM Page 19 Predeveloped UCI File 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:46 PM Page 20 Mitigated UCI File 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:46 PM Page 21 Predeveloped HSPF Message File 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:46 PM Page 22 Mitigated HSPF Message File 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:46 PM Page 23 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. 2005-2019; 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 16-002 Reed Johnson 2019-03-28 3/28/2019 2:24:46 PM Page 24