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HomeMy WebLinkAboutSWP272285(1) ' HDA File No. 9556.00 <u11 r r I " Q E C 3 Q 1996 RECE IVED 81-A+DING DIVISION ��� a 1 1998 WARNER ENGINEERING DRAINAGE CALCULATIONS FOR FARWEST STEEL ' CITY OF RENTON, WASHINGTON t tPrepared By: Bryant O. Mercil, P.E. HORTON DENNIS & ASSOCIATES, INC. 0. 320 Second Avenue South WAS�i4��� Kirkland, Washington 98033-6687 ��'' �Phone: (206) 822-2525 Fax: (206) 822-8758 27991 4iw� S GISTE�� ' December 8, 1996 S�nNAL Revised December 18, 1996 12jl81g6 EXPI S 8/27l 8 ' HDA File No. 9556.00 DRAINAGE CALCULATIONS FOR ' FARWEST STEEL ' CITY OF RENTON, WASHINGTON Prepared By: Bryant O. Mercil P.E. �' , HORTON DENNIS & ASSOCIATES, INC. 320 Second Avenue South Kirkland, Washington 98033-6687 ' Phone: (206) 822-2525 Fax: (206) 822-8758 December 8, 1996 Revised December 18, 1996 TABLE OF CONTENTS Introduction: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .I. . . . . . . . . . . . . . . . . . . . . . 1 Summary of Results: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Basin Summaries: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Runoff Curve Number and Time of Concentration: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 ' Detention Basin Design Data: 19 g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . tWater Quality: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 ' Backwater Analysis: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Drainage Area Map: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 t INTRODUCTION The following computations present the design of a storm water detention system for the proposed Farwest Steel warehouse. The proposed 5.63 acre development is located on the south side of SW 34th Street, east of Lind Avenue in the City of Renton and will be developed in the following two phases: ' Phase One will involve construction of a 63,300 square foot warehouse, 660 square foot temporary office and a 2,096 square foot permanent office. • Phase Two will involve construction of a 32,200 square foot warehouse. EXISTING DRAINAGE CONDITIONS ' The project site is presently a vacant parcel comprised of two recorded parcels (Parcel A of SP 378- 79 and Lot B of the Burlington Northern Railroad Binding Site Plan No. 014 - 92). The parcel was ' filled approximately 18 years ago. The existing ground cover consists mainly of grasses in poor condition over the fill material. The site generally drains from east to west at an average slope of 0.25 percent. PROPOSED DRAINAGE CONDITIONS Runoff from the parking and loading areas in front of the proposed buildings will be conveyed in a storm drain pipe system to grass-lined swales adjacent to the south property line. The swales have been designed with flat slopes to promote water quality prior to discharge into the detention basin. The swale will outfall into the first of three water quality ponds. These ponds have been designed using the methodologies for a combined water quality/detention basin as outlined in the 1990 edition of the King County Surface Water Design Manual (KCSWDM). While the above mentioned grass hn. ed swales will provide some water quality benefits, site constraints precluded the design of a bio- filtration swale meeting the requirements of the KCSWDM. To compensate for use of the smaller swales, additional storage has been provided in the proposed water quality ponds. Additional water quality storage has also been provided to compensate for paved areas downstream of the proposed facility. Calculations for water quality pond surface area and volume begin on page 24 of this report. The proposed detention basin has been designed to maximize the volume available for storage of excess storm water runoff through excavation. The detention basin has been designed to release flows below the pre developed rates for the 2, 10, and 100 year storms. As outlined in the summary of results on pages 3 and 4, the total available volume of detention storage in the proposed facility exceeds the 30% factor of safety needed to satisfy KCSWDM Core Requirement Number 3. The boundaries of the proposed drainage area tributary to the detention facility as well as limits of the bypass and off site areas are delineated on the drainage area map at the end of this report. The ' "Waterworks" program with the Santa Barbara Unit Hydrograph (SBUH) method and King County rainfall distribution (USER 1) was used in the design of the proposed facility. 1 Control in the detention system will be provided by the following set inside of a 54 inch diameter catch basin manhole. ' A 4 inch diameter orifice with an outlet elevation of 11.30 ' An 18 inch diameter restrictor with an overflow elevation of 14.90 In the event that the control system fails in a 100 year storm event, an emergency overflow system ' consisting of a 6 foot wide x 6" high notch on the face of the 54 inch diameter catch basin manhole has been designed to safely convey the 100 year peak discharge from the detention basin directly into the catch basin manhole. The restrictor inside of the manhole has also been sized to safely convey ' the peak 100 year storm without overtopping the perimeter of the detention basin. The control structure will discharge to a 15-inch storm drain pipe. The storm drain pipe will extend ' approximately 375 feet south and west to a connection with an existing catch basin manhole immediately east of Lind Avenue. This pipe has been designed to convey the outflow from the proposed detention facility as well as the pre developed peak flows from the proposed GI Joe Store ' project, east of the site. At the connection with the existing manhole, the flows in the 15-inch pipe are added to the flows from the Home Base detention facility for conveyance in an existing 12 inch storm drain to the existing 60 inch storm drain on the west side of Lind Avenue. The 60-inch storm ' drain pipe continues approximately 550 feet north, then 1,000 feet east to an outfall in Springbrook Creek. A backwater analysis of the outlet pipe from the project site to the existing 60 inch storm drain in Lind Avenue has been provided in this report. The calculations demonstrate that the existing 12 inch ' storm drain pipe has adequate capacity to convey the combined flows. The existing 12 inch storm drain pipe from the manhole to the right of way of Lind Avenue was constructed within an existing 20 foot drainage easement. This easement was established with recordation of the Burlington Northern Binding Site Plan to allow common use of drainage facilities between lots. A "Temporary Erosion and Sedimentation Control Plan" has been prepared that meets the criteria established in Core Requirements No. 5 of the KCSWDM. 2 SUMMARY OF RESULTS ' PROPOSED DETENTION SYSTEM Total Area of Project Site: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.63 Acres ' Less Onsite Bypass Area(Basin No. 3): . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.06 Acres Total Area of Project Site Tributary to Detention Basin: . . . . . . . . . . . . . . . . . . . . . . 5.58 Acres Plus Offsite Areas: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.43 Acres ' Total Area Tributary to Detention Basin(Basin No. 1): . . . . . . . . . . . . . . . . . . . . . . . 6.01 Acres Offsite Bypass Area(Basin No. 2): . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.20 Acres ' 1 YEAR STORM (WATER QUALITY) ' Peak Discharge for Pre Developed Conditions: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N/A Peak Inflow to Basin: . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.58 cfs Proposed Release Rate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.39 cfs ' Design Water Surface Elevation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.60 Approximate Volume of Storage Provided: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,025 cf 2 YEAR STORM Peak Discharge for Pre Developed Conditions (Retained Area), Qex: . . . . . . . . . . . . . . 0.86 cfs Peak Discharge for Pre Developed Conditions (Bypass Areas), Qexbp: . . . . . . . . . . . . . 0.06 cfs Peak Discharge for Post Developed Conditions (Bypass Areas), Qdevbp: . . . . . . . . . . . 0.13 cfs Allowable Release Rate From Detention Basin, Qr= Qexdb + Qexbp - Qdevbp: . . . . . . 0.79 cfs Peak Inflow to Basin: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.38 cfs Proposed Release Rate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.64 cfs Design Water Surface Elevation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.04 Approximate Volume of Storage Provided: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5,652 cf 10 YEAR STORM Peak Discharge for Pre Developed Conditions (Retained Area), Qex: . . . . . . . . . . . . . . 1.63 cfs ' Peak Discharge for Pre Developed Conditions (Bypass Areas), Qexbp: . . . 0.12 cfs Peak Discharge for Post Developed Conditions (Bypass Area), Qdevbp: . . . . . . . . . . . . 0.18 cfs Allowable Release Rate From Detention Basin, Qr= Qexdb + Qexbp - Qdevbp: . . . . . . 1.57 cfs Peak Inflow to Basin: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.70 cfs Proposed Release Rate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.72 cfs Design Water Surface Elevation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.57 Approximate Volume of Storage Provided, Vsp: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13,062 cf Total Volume of Storage Required, Vsr= 1.30 x Vsp: . . . . . . . . . . . . . . . . . . . . . . . . . 16,981 cf Total Volume of Storage Provided at Maximum WS Elevation (14.90): . . . . . . . . . . . . 17,725 cf i 3 1 1 100 YEAR STORM ' Peak Discharge for Pre Developed Conditions (Retained Area), Qex: . . . . . . . . . . . . . . 2.56 cfs Peak Discharge for Pre Developed Conditions (Bypass Areas), Qexbp: . . . . . . . . . . . . . 0.18 cfs ' Peak Discharge for Post Developed Conditions (Bypass Areas), Qdevbp: . . . . . . . . . . . 0.26 cfs Allowable Release Rate From Detention Basin, Qr= Qexdb + Qexbp - Qdevbp: . . . . . . 2.48 cfs Peak Inflow to Basin: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.14 cfs Proposed Release Rate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.26 cfs Design Water Surface Elevation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.01 ' Approximate Volume of Storage Provided: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19,281 cf 1 1 1 r r 1 r 1 i 1 1 , 1 4 r SUMMARY OF RESULTS HISTORY OF HYDROGRAPH ACTIVITY ' Date of Session: 12/8/96 11:37:41 am ' LPOOL 1 "WATER QUALITY STORM" B1-WQ-1 B1-WQ-1 S1 D3 1 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume WATER QUALITY STORM 0.58 0.58 S1 D3 13.60 0.39 1 1025.00 cf ' LPOOL 2 "2 YEAR STORM" 0.81 B1-DE2 S1 D3 2 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 2 YEAR STORM 0. 81 2.38 S1 D3 14.04 0. 64 2 5652. 18 cf ' LPOOL 3 "10 YEAR STORM" 1.58 B1-DE10 S1 D3 3 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 10 YEAR STORM 1.58 3.70 S1 D3 14.57 0.72 3 13062.39 cf ' LPOOL 4 "100 YEAR STORM" 2.50 B1-DE100 S1 D3 4 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 100 YEAR STORM 2.50 5.14 S1 D3 15.01 1.26 4 19280. 88 cf i 1 1 5 1 d BASIN SUM-lARIE S ' PRE DEVELOPED CONDITIONS BASIN NO. 1 - RETAINED AREA TO DETENTION BASIN ' BASIN ID: B1-EX2 NAME: BASIN NO. 1 - EX 2 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 6.01 Acres BASEFLOWS: 0. 00 cfs ' RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 2.00 inches AREA. . : 6.01 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 89. 00 0.00 TC. . . . : 45.00 min 0.00 min ' ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 86 cfs VOL: 0.51 Ac-ft TIME: 490 min ' BASIN ID: B1-EX10 NAME: BASIN NO. 1 - EX 10 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 6.01 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 2.90 inches AREA. . : 6.01 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 89.00 0. 00 TC. . . . : 45.00 min 0.00 min ABSTRACTION COEFF: 0.20 ' PEAK RATE: 1.63 cfs VOL: 0.91 Ac-ft TIME: 490 min BASIN ID: B1-EX100 NAME: BASIN NO. 1 - EX 100 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 6.01 Acres BASEFLOWS: 0. 00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 3.90 inches AREA. . : 6.01 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 89. 00 0.00 TC. . . . : 45. 00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 2.56 cfs VOL: 1.37 Ac-ft TIME: 480 min 7 BASIN NO. 2 OFFSITE BYPASS AREA ' BASIN ID: B2-EX2 NAME: BASIN NO. 2 - EX 2 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.20 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP ' PRECIPITATION. . . . : 2.00 inches AREA. . : 0.20 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 89.00 0.00 TC. . . . : 10.00 min 0.00 min ABSTRACTION COEFF: 0.20 ' PEAK RATE: 0.05 cfs VOL: 0.02 Ac-ft TIME: 480 min BASIN ID: B2-EX10 NAME: BASIN NO. 2 - EX 10 YR STORM ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.20 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP ' PRECIPITATION. . . . : 2.90 inches AREA. . : 0.20 Acres 0. 00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 89.00 0. 00 TC. . . . : 10.00 min 0.00 min ABSTRACTION COEFF: 0.20 ' PEAK RATE: 0.09 cfs VOL: 0.03 Ac-ft TIME: 480 min BASIN ID: B2-EX100 NAME: BASIN NO. 2 - EX 100 YR STORM ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.20 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 3.90 inches AREA. . : 0.20 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 89.00 0.00 TC. . . . : 10.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.14 cfs VOL: 0.05 Ac-ft TIME: 480 min 8 1 BASIN NO. 3 ONSITE BYPASS AREA ' BASIN ID: B3-EX2 NAME: BASIN NO. 3 - EX 2 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.06 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP ' PRECIPITATION. . . . : 2.00 inches AREA. . : 0.06 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 89.00 0. 00 TC. . . . : 10.00 min 0.00 min ABSTRACTION COEFF: 0.20 ' PEAK RATE: 0.01 cfs VOL: 0.01 Ac-ft TIME: 480 min BASIN ID: B3-EX10 NAME: BASIN NO. 3 - EX 10 YR STORM ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.06 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP ' PRECIPITATION. . . . : 2.90 inches AREA. . : 0.06 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 89. 00 0.00 TC. . . . : 10.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.03 cfs VOL: 0.01 Ac-ft TIME: 480 min BASIN ID' B3-EX100 NAME: BASIN NO. 3 - EX 100 YR STORM ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.06 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 3.90 inches AREA. . : 0.06 Acres 0. 00 Acres ' TIME INTERVAL. . . . : 10.00 min CN. . . . : 89.00 0.00 TC. . . . : 10.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.04 cfs VOL: 0.01 Ac-ft TIME: 480 min 9 BASIN NO. 4 PROPOSED GI JOE STORE BASIN ID: B4-EX2 NAME: BASIN NO. 4 - EX 2 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 4.70 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 2.00 inches AREA. . : 4.70 Acres 0. 00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 89.00 0.00 TC. . . . : 90.00 min 0.00 min ABSTRACTION COEFF: 0.20 ' PEAK RATE: 0.47 cfs VOL: 0.40 Ac-ft TIME: 500 min t BASIN ID: B4-EX10 NAME: BASIN NO. 4 - EX 10 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 4.70 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP ' PRECIPITATION. . . . : 2.90 inches AREA. . : 4.70 Acres 0. 00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 89.00 0.00 TC. . . . : 90.00 min 0.00 min ABSTRACTION COEFF: 0.20 ' PEAK RATE: 0. 91 cfs VOL: 0.71 Ac-ft TIME: 500 min BASIN ID: B4-EX100 NAME: BASIN NO. 4 - EX 100 YR STORM ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 4.70 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 3.90 inches AREA. . : 4.70 Acres 0. 00 Acres ' TIME INTERVAL. . . . : 10.00 min CN. . . . : 89.00 0.00 TC. . . . : 90.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 1.44 cfs VOL: 1.07 Ac-ft TIME: 490 min 10 BASIN SUMMARIES POST DEVELOPED CONDITIONS BASIN NO. 1 - RETAINED AREA TO DETENTION BASIN ' BASIN ID: B1-WQ-1 NAME: BASIN 1, WATER QUALITY STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 6.01 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 0.67 inches AREA. . : 6.01 Acres 0.00 Acres TIME INTERVAL. . . . . 10.00 min CN. . . . . 97.00 0.00 TC. . . . : 12.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.58 cfs VOL: 0.20 Ac-ft TIME: 480 min BASIN ID: B1-DE2 NAME: BASIN NO. 1 - DEV. 2 YR STORM ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 6.01 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 2.00 inches AREA. . : 6.01 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 96.00 0.00 TC. . . . : 12.00 min 0.00 min ABSTRACTION COEFF: 0.20 ' PEAK RATE: 2.38 cfs VOL: 0.79 Ac-ft TIME: 480 min BASIN ID: B1-DE10 NAME: BASIN NO. 1 - DEV. 10 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 6.01 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 2.90 inches AREA. . : 6.01 Acres 0.00 Acres ' TIME INTERVAL. . . . : 10.00 min CN. . . . : 96.00 0.00 TC. . . . : 12.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 3.70 cfs VOL: 1.23 Ac-ft TIME: 480 min BASIN ID: B1-DE100 NAME: BASIN NO. 1 - DEV. 100 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . . 6.01 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 3.90 inches AREA. . : 6.01 Acres 0. 00 Acres ' TIME INTERVAL. . . . : 10.00 min CN. . . . : 96.00 0.00 TC. . . . : 12.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 5.14 cfs VOL: 1.72 Ac-ft TIME: 480 min ' 11 BASIN NO. 2 OFFSITE BYPASS AREA BASIN ID: B2-DE2 NAME: BASIN NO. 2 - DEV. 2 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.20 Acres BASEFLOWS: 0.00 cfs ' RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 2.00 inches AREA. . : 0.20 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 98. 00 0.00 TC. . . . : 6.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.10 cfs VOL: 0.03 Ac-ft TIME: 470 min BASIN ID: B2-DE10 NAME: BASIN NO. 2 - DEV. 10 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.20 Acres BASEFLOWS: 0.00 cfs ' RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 2.90 inches AREA. . : 0.20 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 98.00 0. 00 TC. . . . . 6.00 min 0.00 min ' ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 14 cfs VOL: 0.04 Ac-ft TIME: 470 min BASIN ID: B2-DE100 NAME: BASIN NO. 2-DEV. 100 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.20 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP ' PRECIPITATION. . . . : 3.90 inches AREA. . : 0.20 Acres 0. 00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 98.00 0.00 TC. . . . : 6.00 min 0•.00 min ABSTRACTION COEFF: 0.20 ' PEAK RATE: 0.20 cfs VOL: 0.06 Ac-ft TIME: 470 min 12 BASIN NO. 3 ONSITE BYPASS AREA ' BASIN ID: B3-DE2 NAME: BASIN NO. 3 - DEV. 2 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.06 Acres BASEFLOWS: 0.00 cfs ' RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 2.00 inches AREA. . : 0.06 Acres 0.00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 98.00 0. 00 TC. . . . : 6.00 min 0.00 min ' ABSTRACTION COEFF: 0.20 PEAK RATE: 0.03 cfs VOL: 0.01 Ac-ft TIME: 470 min ' BASIN ID: B3-DE10 NAME: BASIN NO. 3 - DEV. 10 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.06 Acres BASEFLOWS: 0.00 cfs ' RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 2.90 inches AREA. . : 0.06 Acres 0. 00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 98.00 0.00 ' TC. . . . : 6. 00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.04 cfs VOL: 0.01 Ac-ft TIME: 470 min ' BASIN ID: B3-DE100 NAME: BASIN NO. 3-DEV. 100 YR STORM SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.06 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER1 PERV IMP PRECIPITATION. . . . : 3. 90 inches AREA. . : 0. 06 Acres 0. 00 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 98.00 0.00 TC. . . . : 6.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.06 cfs VOL: 0.02 Ac-ft TIME: 470 min 13 RUNOFF CURVE NUMBER TIME OF CONCENTRATION 1 14 ' FARWEST STEEL RUNOFF CURVE NUMBER TIME OF CONCENTRATION BASIN NO. 1 -DETENTION BASIN-PRE DEVELOPED CONDITIONS Soil Name and Cover Description Runoff Curve Area Hydrologic Soil Group Number (Acres) Name HSG RCN A RCN x A Snohomish D Meadow(Good Condition) 89 6.01 534.89 ' Totals 1 6.01 534.89 ' Runoff Curve Number= (RCN x A)/A:................................................................................. 89.00 Runoff Curve Number Used in Basin Hydrograph Calculation:................................................. 89.00 ' Time of Concentration Used in Basin Hydrograph Calculation(Minutes):................................. 45.00 BASIN NO. 2- OFFSITE BYPASS AREA-PRE DEVELOPED CONDITIONS ' Soil Name and Cover Description Runoff Curve Are a Hydrologic Soil Group Number (Acres) Name HSG RCN A RCN x A ' Snohomish D Meadow(Good Condition) 89 0.20 17.98 ' Totals 0.20 17.98 Runoff Curve Number=(RCN x A)/A:................................................................................. 89.00 Runoff Curve Number Used in Basin Hydrograph Calculation:................................................. 89.00 Time of Concentration Used in Basin Hydrograph Calculation (Minutes):................................. 10.00 9556RCN.XLS 15 12/8/96 ' FARWEST STEEL RUNOFF CURVE NUMBER ' TIME OF CONCENTRATION BASIN NO. 3- ONSITE BYPASS AREA-PRE DEVELOPED CONDITIONS ' Soil Name and Cover Description Runoff Curve Area ' Hydrologic Soil Group Number (Acres) Name HSG RCN A RCN x A Snohomish D Meadow(Good Condition) 89 0.06 5.04 ' Totals 0.06 5.04 ' Runoff Curve Number=(RCN x A)/A:................................................................................. 89.00 Runoff Curve Number Used in Basin Hydrograph Calculation:................................................. 89.00 ' Time of Concentration Used in Basin Hydrograph Calculation(Minutes):................................. 10.00 ' BASIN NO. 4- PROPOSED GI JOE STORE-PRE DEVELOPED CONDITIONS Soil Name and Cover Description Runoff Curve Area ' Hydrologic Soil Group Number (Acres) Name HSG RCN A RCN x A ' Snohomish D Meadow(Good Condition) 89 4.70 418.30 ' Totals 4.70 418.30 Runoff Curve Number=(RCN x A)/A:................................................................................. 89.00 Runoff Curve Number Used in Basin Hydrograph Calculation:................................................. 89.00 Time of Concentration Used in Basin Hydrograph Calculation(Minutes):................................. 55.00 9556RCN.XIS 16 12/8/96 ' FARWEST STEEL RUNOFF CURVE NUMBER ' TIME OF CONCENTRATION BASIN NO. I -DETENTION BASIN-POST DEVELOPED CONDITIONS Soil Name and Cover Description Runoff Curve Area Hydrologic Soil Group Number (Acres) ' Name HSG RCN A RCN x A Snohomish D Lawn/Landscaped Areas 90 1.32 118.89 Snohomish D Impervious Areas 98 4.32 423.53 Snohomish D Detention Basin 100 0.37 36.73 ' Totals 6.01 579.15 Runoff Curve Number= (RCN x A)/A:................................................................................. 96.36 Runoff Curve Number Used in Basin Hydrograph Calculation:................................................. 96.00 Time of Concentration Used in Basin Hydrograph Calculation(Minutes):................................. 12.00 ' BASIN NO. 2- OFFSITE BYPASS AREA- POST DEVELOPED CONDITIONS ' Soil Name and Cover Description Runoff Curve Area Hydrologic Soil Group Number (Acres) Name HSG RCN A RCN x A Snohomish D Lawn/Landscaped Areas 90 0.00 0.00 Snohomish D Impervious Areas 98 0.20 19.79 Snohomish D Detention Basin 100 0.00 0.00 Totals 0.20 19.79 ' Runoff Curve Number=(RCN x A)/A:................................................................................. 98.00 ' Runoff Curve Number Used in Basin Hydrograph Calculation:................................................. 98.00 Time of Concentration Used in Basin Hydrograph Calculation(Minutes):................................. 6.00 ' 9556RCN.XLS 17 12/8/96 ' FARWEST STEEL RUNOFF CURVE NUMBER TIME OF CONCENTRATION ' BASIN NO. 3 - ONSITE BYPASS AREA -POST DEVELOPED CONDITIONS ' Soil Name and Cover Description Runoff Curve Area Hydrologic Soil Group Number (Acres) Name HSG RCN A RCN x A Snohomish D Lawn/Landscaped Areas 90 0.00 0.00 ' Snohomish D Impervious Areas 98 0.06 5.55 Snohomish D Detention Basin 100 0.00 0.00 ' Totals 0.06 5.55 Runoff Curve Number= (RCN x A)/A:................................................................................. 98.00 Runoff Curve Number Used in Basin Hydrograph Calculation:................................................. 98.00 Time of Concentration Used in Basin Hydrograph Calculation(Minutes):................................. 6.00 ' 9556RCN.XLS 18 12/8/96 1 ' DETENTION BASIN DESIGN DATA ' 19 STAGE STORAGE TABLE CUSTOM STORAGE ID No. S1 Description: PROPOSED DETENTION BASIN ' STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- ==__����an=�_a=e_a=s__=maa_______________�__�_____________��6s�_____�___ 13.50 0.0000 0.0000 13.90 9100 0.0941 14.30 9325 0.2191 14.70 14925 0.3426 ' 13.60 1025 0.0235 14.00 5125 0.1177 14.40 10725 0.2462 14.80 16325 0.3748 13.70 2050 0.0471 14.10 6525 0.1498 14.50 12125 0.2784 14.90 17725 0.4069 13.80 3075 0.0706 14.20 7925 0.1819 14.60 13525 0.3105 15.00 19125 0.4390 1 20 STAGE DISCHARGE TABLES ' DISCHARGE LIST ID No. D3 Description: CATCH BASIN NO. 4 ' STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- 13.50 0.0000 14.10 0.6500 14.70 0.7350 15.30 3.7967 ' 13.60 0.5700 14.20 0.6650 14.80 0.7475 15.40 5.1933 13.70 0.5900 14.30 0.6800 14.90 0.7600 15.50 6.5900 13.80 0.6050 14.40 0.6950 15.00 1.2200 13.90 0.6200 14.50 0.7100 15.10 1.6100 14.00 0.6350 14.60 0.7225 15.20 2.4000 ' MULTIPLE ORIFICE ID No. 02 (USED IN DEVELOPMENT OF DISCHARGE LIST D3) Description: RESTRICTOR MH - BASIN NO. 1 ' Outlet Elev: 11.86 (Approx. elevation of hydraulic gradient in the outflow pipe at the max. discharge through the orifice) Elev: 9.30 ft Orifice Diameter: 4.0000 in. STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- 11.86 0.0000 12.70 0.3979 13.60 0.5727 14.50 0.7055 11.90 0.0868 12.80 0.4210 13.70 0.5890 14.60 0.7187 12.00 0.1625 12.90 0.4428 13.80 0.6048 14.70 0.7317 12.10 C.2127 13.00 0.4636 13.90 0.6202 14.80 0.7445 12.20 0.2532 13.10 0.4835 14.00 0.6352 14.90 0.7570 12.30 0.2880 13.20 0.5026 14.10 0.6498 15.00 0.7694 12.40 0.3191 13.30 0.5210 14.20 0.6642 15.10 0.7815 12.50 0.3474 13.40 0.5388 14.30 0.6782 15.20 0.7935 12.60 0.3735 13.50 0.5560 14.40 0.6920 ' RISER DISCHARGE ID No. R1 (USED IN DEVELOPMENT OF DISCHARGE LIST D3) Description: RISER IN RESTRICTOR NH Riser Diameter (in) : 18.00 elev: 14. 90 ft Weir Coefficient. . . : 9.739 height: 16. 00 ft ' Orif Coefficient. . . : 3.782 increm: 0. 10 ft STAGE -----DISCHARGE_-->---STAGE --<--DISCHARGE--->---STAGE --<--DISCHARGE--->-__STAGE --<--DISCHARGE--->--- (ft) ---cfs-- -- (ft) ---cfs-- -- (ft) ---cfs-- -- (ft) ---cfs-- -- 14.90 0.0000 15.20 2.4004 15.60 7.1196 16.00 8.9248 14.90 0.0000 15.30 3.6957 15.70 7.6111 15.00 0.4620 15.40 5.1649 15.80 8.0728 15.10 1.3066 15.50 6.5914 15.90 8.5095 BROAD CRESTED WEIR ID No. BW-1 Description: Overflow - Detention Basin cd: 3.0300 Weir length: 3.5340 ft. El: 14.90 ft. Weir Increm: 0.10 ' STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- 14.90 0.0000 15.10 0.9578 15.30 2.7089 15.50 4.9766 21 d d W [� N N WATER QUALITY ' Reference: King County Surface Water Design Manual BIOFILTRATION Section 1.2.3 Core Requirement No. 3 ' Threshold for Biofiltration: Maximum Allowable Impervious Area Subject to Vehicular Traffic, Aimp: . . . . . . . . . . . . . . . . . . 5,000 SF ' Proposed Condition: Total Impervious Area Subject to Vehicular Traffic, Aimp: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97,184 SF On Site Area Subject to Vehicular Traffic: . . . . . . . . . . . . . . . . . . . . . . . . . 88,386 SF ' Off Site Area Subject to Vehicular Traffic: . . . . . . . . . . . . . . . . . . . . . . . . . . 8,798 SF ' Biofiltration is required. Because of constraints on site grading, the surface area proposed in the grass-lined swale outfall to the water quality ponds does not meet the design standards outlined in the manual. In order to compensate for the loss of biofiltration area, the proposed wetponds have been enlarged to provide additional ' surface area and storage volume. The calculations for the proposed wetponds are presented on the following page. t ' 23 SPECIAL WATER QUALITY CONTROLS ' Section 1.3.5 Special Requirement No. 5 As outlined in the introduction,the proposed detention system outfalls to an existing storm drain pipe system in Lind Avenue for eventual discharge into Springbrook Creek, a Class 2 stream. Since the project site proposes discharge within a one mile radius of a Class 2 Stream, a wetpond is required. The engineering plans propose a three cell combination wetpond - detention pond. Since the surface area of the proposed grass lined swale could not meet the biofiltration requirements outlined in the SWM Manual, additional surface area and storage volume has been proposed for the wetponds. As shown ' in the following calcuiations, the proposed wet ponds provide over four times the required wetpond surface area and over two time the required wetpond storage volume. This additional surface area and storage volume is ' intended to compensate for the limited surface area in the proposed grass lined swale. WETPOND DESIGN ' Surface Area Total Impervious Area, Aimp: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197,051 SF On Site Impervious Area: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188,253 SF Bypass Impervious Area: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,798 SF Required Water Quality Surface Area, Awq: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,971 SF Awq = One Percent of Total Impervious Area ' Proposed Water Quality Surface Area, Apwq: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,500 SF Ratio of Proposed Water Quality Surface Area to Required Quality Water Surface Area: . . . . . . 4.31 Section 1.3.5(2) Storage Volume ' Required Storage Volume, Vwq: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,712 CF Vwq = Total Volume of Runoff from the Mean Annual Storm ' Vwq = 0.20 Acre-Feet x 43,560 (See Page 7 for Basin Summary) Total Drainage Area, A: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.01 Acres Farwest Steel Project: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.58 Acres ' Offsite Areas Tributary to Detention Basin: . . . . . . . . . . . . . . . . . 0.43 Acres Access Driveway to Lind Avenue: . . . . . . . . . . . . . . . . . . . . . . . . 0.20 Acres ' Proposed Storage Volume, Vwq: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19,275 CF Ratio of Proposed Storage Volume to Required Storage Volume: 2.21 ' The volume calculations for the proposed wetponds are presented on the following page. ' 24 12/8/96 10:24 AM WATER QUALITY PONDS VOLUME CALCUALTIONS POND NO. 1 WS Area Avg. Area Depth Inc. Volume Total Volume Elevation Square Feet Square Feet Feet Cubic Feet Cubic Feet ' 10.50 1,100.00 0.00 1,400.00 1.50 2,100.00 12.00 1,700.00 2,100.00 ' 2,050.00 1.50 3,075.00 13.50 2,400.00 5,175.00 ' POND NO. 2 ' WS Area Avg. Area Depth Inc. Volume Total Volume Elevation Square Feet Square Feet Feet Cubic Feet Cubic Feet ' 10.50 2,400.00 0.00 2,750.00 1.50 4,125.00 ' 12.00 3,100.00 4,125.00 3,450.00 1.50 5,175.00 13.50 3,800.00 1 9,300.00 POND NO. 3 WS Area Avg. Area Depth Inc. Volume Total Volume Elevation Square Feet Square Feet Feet Cubic Feet Cubic Feet 10.50 900.00 0.00 1,250.00 1.50 1,875.00 12.00 1,600.00 1,875.00 1,950.00 1 1.50 1 2,925.00 13.50 2,300.00 1 1 1 1 4,800.00 Total Surface Area Provided:................................................................................ 8,500.00 Square Feet Total Volume Provided:. 19,275.00 Cubic Feet ' WQSTOI.XLS 25 12/8/96 COALESCING PLATE OIL/WATER SEPARATOR ' Section 1.3.6 Special Requirement No. 6 Threshold for Coalescing Plate Oil/Water Separator ' Maximum Allowable Impervious Area Subject to Vehicular Traffic, A imp: . . . . . . . . . . . . . . . . . 5.00 Acres Maximum Number of Vehicle Trips Per Day: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,500 Trips ' Proposed Condition: Total Impervious Area Subject to Vehicular Traffic, Aimp: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.23 Acres Aimp = 97,184 SF/43,560 Since the proposed impervious area subject to vehicular traffic is less than the 5.00 acre threshold, an coalescing ' plate oil/water separator is not required. 1 26 � 27 D A C K W A T E R C A L C U L A T I O N S H E E T C X (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) M Z Bar Fric- Entr Entr Exit Outlt Inlet Appr Bend Junc D. O Pipe Outlt Inlet Barrel Barrl Vol TW tion HGL Head Head Contr Contr Vol Head }lead HW is Segment 9 Lngth Pipe "n•• Elev Elev Area Vol Head Elev Loss Elev Loss Loss Elev Elev Head Loss Loss Elev A n CB to CB (ofs) (ft) Size Value (ft) (ft) (sqft) (fps) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) O 2 YEAR STORM > Z CONN C8 1.53 35 16 0.015 q,10 1,16"1 0,8"1 0,01 10.60 0,02 10.62 0.01 0.01 10.64 10,48 0,0► a.0 1 0•0l 10.65 E$ _t$ 1.11 f2 15 0,013 Q,85 q•Ra 1.22-7 o,610 o.01 10,65 0,01 to,66 0.01 0.01 lo.6 4 .0 a 10. � 0.01 0.01 00 10,68 c1 1 111 301 15 0,015 q,q0 11,00 1.22,1 o,QO 0.01 10,66 0. 10 10,16 0,01 0,01 to-go 11.5'1 0,01 0,01 O,o! c1.58 � a CZ 4 O.G4 12 12 0.013 11.00 11.30 0.-185 0.81 0,01 11.58 0.01 11.59 0.01 0.01 11.61 1t.06 0.00 0,00 0.00 11,86 a H 10 YEAR 570RM z CONN r_L3 2.41 q5 18 0,015 Q,10 q.84 1,-161 L36 0,05 10.60 0.05 10,65 0.03 0.05 10.13 10,6.1 0.03 0.01 0.01 10.14 ,a� O CB �� 1.63 12 15 0.013 °L85 q,00 1,n7 1,53 0,03 10,14 0,01 10,15 an o,03 t0:1q to.60 0-03 0.02 0,00 10,60 Z O CIS Z 1,65 501 15 0,013 0I.g0 11.00 1,227 1.35 0,03 10.60 0,2.0 10.85 o,02 0.0-5 10,g0 11.12 0.05 O.o2 0,01 11.12 CA z 2 4 f\3 0,72 72 12 0,013 II.Oo 11,30 0.-185 O.q2 O,ol 11:12- 0.03 Ill.-15 O,o1 0;01 11.-1-1 11,86 0,00 0,00 0.00 11,06 M 100 YEAR 570RM � EX EX 'T► CONN CB 4.15 Lj5 l8 0,013 q,10 9,84. I,"167 2.34 0.08 10.60 0.15 10 1S 0,04 0.08 10.8-7 lO,198 0.01 0.05 0,02 10.'16 a Ex CO 2�0 12 15 0,013 n CS i q•85 q,qo 1.2z'1 2,� 0,01 t0,g6 0.02 10.q$ O.D4 0.0'1 11,Oq 10.82 O.fl� 0,03 O.00 I1,05 CIS Z 2r10 501 15 0,013 q,qo 11,00 1,227 2.20 0.01 11,05 0,52 11.5"1 o,0a- 0.0-7 11,68 II,g1 0,04 O,ol O.o1 I1,G5 � Z CB 1,26 '72 12 0,015 11,00 11,30 0,"765 1.60 0.04 11.C15 O,OR 12,04 0,02 0,04 12.10 11•g6 O.00 o.00 o.00 12.10 a v m Z a Z c a � r 0 BACWATER ANALYSIS ' PEAK DISCHARGE TABULATION ' EX. CONN TO EX. CB Farwest Steel GI Joe Store Home Base Total Flow ' 2 Year Storm 0.64 0.47 0.42 1.53 10 Year Storm 0.72 0.91 0.78 2.41 100 Year Storm 1.26 1.44 1.43 4.13 ' EX. CB TO CB NO. 2 Farwest Steel GI Joe Store Home Base Total Flow 2 Year Storm 0.64 0.47 0.00 1.11 10 Year Storm 0.72 0.91 0.00 1.63 ' 100 Year Storm 1.26 1.44 0.00 2.70 CB NO. 2 TO CB NO. 4 ' Farwest Steel GI Joe Store Home Base Total Flow ' 2 Year Storm 0.64 0.00 0.00 0.64 10 Year Storm 0.72 0.00 0.00 0.72 100 Year Storm 1.26 0.00 0.00 1.26 ' NOTES See page 10 for peak flows from GI Joe Store See page following page for peak flows from Home Base ' 9556BW.XLS 29 12/8/96 ' HOME BASE SUMMARY OF RESULTS PROPOSED DETENTION SYSTEM ' Total Area of Project Site: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.65 Acres Less Bypass Area: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.77 Acres ' Total Site Area Tributary to Detention Basin: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.88 Acres Plus Offsite Wetland Mitigation Area: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.76 Acres Total Area Tributary to Detention Basin: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.64 Acres 2 YEAR STORM Peak Inflow to Basin: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.06 cfs ' Proposed Release Rate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.42 cfs Proposed Release Rate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.04 cfs/ acre Design Water Surface Elevation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.81 ' Approximate Volume of Storage Provided: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46,500 cf 10 YEAR STORM Peak Inflow to Basin: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.52 cfs ' Proposed Release Rate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.78 cfs Proposed Release Rate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.07 cfs/ acre Design Water Surface Elevation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.33 ' Volume of Storage Provided: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72,000 cf ' 100 YEAR STORM ' Peak Inflow to Basin: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.22 cfs Proposed Release Rate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.43 cfs Proposed Release Rate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.12 cfs/acre ' Design Water Surface Elevation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.47 . . . . . . . . . . . . . . . . . . . . . . . . . . . .Volume of Storage Provided: . 82,000 cf ' 30 4 Q d W d W C7 d A M ' BASIN N0. 3 LA. I. BYPASS AREA = 0.06 ACRES E,2CONG(SENW)-,270 EL RM-10.4e RN-I&O IY I LE CCCNG SW)-1172 IE rCONC(N}1S.03 I.E.e'OONGM}t4.7e LE tl'CONC.(E}t].s2 I.E r'CON0.(5LW4-114e STREET UDNT ON LE p'CONC ).1153 80T..te.0 e0Tr147 SOT.-120 w- > 3 7 CONG BASE RI,f7a° CAA.FLOWIIIE(N,wE)-411e SO'E.-724 RIw-IaW lE a'CGIIG N 8.62 ' DTa B PVC(SNW,SWp).ax - - - S.W. 34T STRE T tx e®oaNc(wrllse f " 14 fla-laD! IE CCONC.(NE)-14.22 b EEL FIRE EEIDRANT IE SCGNG(N}1117 �' 70•x 5'S5 e•99 Y9S fS•SS �6 Y9$ e'SS 38'SD e1+4A17 Uf0 Am - m a-CONC CURB!fAITTER MRS CUT ! �1°� R.BBER PVM7 ' IX ASPNKT m+4A17 8 N8750'23' 110.85' 8 E.ASPHALT 8 Q 8 8 EX ASPNALT2- 8 8 \ Q PAD IX td dV(DS ! POWER / 4x'.GRASS UNm SWAlE!0.501L 7°� MMKEII /1-r T n IFLw Cd( '•^P +. + MARKER OL 12'GATE VALVE IN WAILER NN w. TE1AH O++ .SIGN / IX1YW M1]'W EK.IYWIX12M TER NN 0 1 .G 1.49 I N0. y wM-laal II- F 1d WOSCAPE! I EX ARE HYDRANT ALTtim 0. FUTURE 0.S NRE 0. 0 9ono'Do• nun E]i T. / N01 O9'E-148.5' ® I ® o.s a / E 12 cDNGM}121LT R-55.X)'32• 9M-1a54 -86J36 \ LE (E}t2p7 / ��Y^C RETAINNO WALL I_ O" / °. N I hJ C \ / L=88.OB 7dMw1NE(SN}0.04 / 0OT.-t2J T l� �E SiN/ONpAL PIANS IFNO 32A INV-iS INV-1 I INV-1a79 INV-1e. IX ARE NYORMT IN T lat m0 / \J _ C I.E 1YC011GM}7250 �M 1 WAILER W EL 1Y OAIE VALVE IN VAULT RIA9:T10 WNE11p19: � - /' ® 3°�-- ' cne II'PVC(S,IE)-7.1a \\N RM-t°.e4 \ \ 1+ 't© (�3M sv.�) f� T(Tro.f -1°� \ Ex.1D'unun EA9:LtENr\\\ IE��e'm ~ 1 I oc \ / I WIN as a rw. As +® , mu I.E tYcaG(w}t ass - ta.mG l.. C� r IE Js'�)-a7s CTIL PVC(SFE}77 SDOO N0. SDCO NO.33 ® 'RARROAO IE Je' 9 7.fe I.m0 RIM-fax RIM-tax RIM-1650 -1 CB N0.17 \IE 4e' 5. RM IA T 3 INV-16.00 INV-15.15 INV-15A5 �4 8 INV-70.70 NO.16 Q \ LE.1YWNC.(NW>-14,27 IX 20'URUTY EASEMENT Hamra rrfM n"!Os I n Y .' � 4101. CONO SA9[ A (DROP INVFR DRAINAGE DIVIDE IQ p' I I s mp No.. 00 SOLD�D \ wTN Su PUI'ai0 I \ ■P e7HB '� P N A 8 8 O N I! ERN.1A00 t >° 1 \ * WARGMOUBG63.300 I I - •2 Nv-tax-5'GUT A' I I \ P. \\\ ty Ip0 I NOTE, 7L AN.FLOOR 70.0° 24'+TR GRAIN Fr. MI SEE PLIINBING PUN INV-14.5D UPPER T \ tM p5 1 CONTINUATION OF I I INV-twD°IAWJ1 •..,� �7 sTAs pLA�SOB /' l LOT I ROOF DRAINS 7*;- 01.DD. sIISLIDfaR01!0ter eA-7.0 H�f0.024-U IE 1rCONC�E�i a41 LE IrCONC(MT-14.M(vp CB N0 15 OL 3d RNLIN7AD / IE Je'CwIG s m m 2 EA4ANDIT E 38'WN a27LOa s =o.,.20E ® +® t / t.CW-(p. I.E.rcow.(N)-12.78 SIlfID a Or=PI.�1�FOR \ P / LMDscM1e e q� �-' ii ii•cMWf,-14i.4T'1 ' > I , 50T.-1QIL s RIM N lid $O ' � NV-um1-112 NV-15.50 a0d I ww 1 1AY0 EX ID'UMUTY EAST � UTUTY E9AT. I T l 77y""M""4 a°f0 4 D.s aolr D.s ® D. Nv.tax D.s i A=78'03'49' WATER LN a i POWER 1 C ® ® + 7 R=443.3r C t 0 I MARKER ) \ IX 30'RAEROAD EASEMENT "L. ..21 TEMPMMV ® Lu wn aA m 7O�8'3B• Q ° ' IXmatW aJ1d ITY M. ! R-.711-' 1 I.E.1YCCNC.(SN}5.0.1 T UTILITY L-471.777BBB Nv-t5.x / \ e CB N0.13 'o I - +� Lam- �e 10 BASIN NO. 4 WY 'A M 1 / ou ALL N.sA ®troo a 5z SD+ - ® I ® - AREA = 4.70 A RES E 11YDDNG,(sp�J-137z b + co ce WATER ALl OND NO ac IE 1YCGNG(E}fa7a BASIN N0. 1 Q E 1roDNe('N}11ee E WCOW.cM,-14.x < � � / / PROPOSED GI J E STORE J RETAINED �REA = 6.01 ACRES / Q ® �� o e WATER QUALITY POND N0.2 t ® DRAINAGE DIVIDE INTAKE NO.1A O 3 INTAKE NO.48 e � B N0. I N am OPPICC c ' CB NO.11 E 1YWNCM I-I&GS ' S7 GO ( / Na 5B Lr .roe Sn Fr. -I j to'-1Y PER SO 1 xY-t INTAKE N PER sD [] m rtN.nmR.IA7D °•poc m e l.aw wN. I Ex so (E}, r+�i�T stue-ouT j c ! I ® ® 'a //a/ m'- I iE 3D CORt ii° WATER UALTY POND N0.1 - POM OF Ell.FR00 1 l N0. F OUTFALL NO.11A ' IX SSNN ELEV.-law / _ + 01G T- 7 FL S:ENa81 is ` a- ,a m / ' TEMP.90! O eWN.E EX. -tee ElL SIYNE LE IYCONC.(E)-- 1rCONGCYO-'ISO 14,83 S LE 1�'CONG(W}tae8 LE tY .`(CONC5}} /1°f JM 148750'47W 517.58' °° LE ASP S7 BERN N8750'4Y �• a E.9WALE 164.90 _� e•00NG aRe!(2177ER A � sIREEr uowr ON 18WIN e R EIL(wNe I7.gB IX lYw IX NEnTOEe AET.wALL IX 10 MEVSfONE REi.WAIL AaWHALT IX 1Y or WAIFIt ' LE ASP 1a7M PAT- I 1 �O[1vmaN POND A m D5.8702-33'S9• Q ' -0751'28• R=80.5.87 -03'49'3Y IX,s'petl Tr = E1L 20'UTILITY EASEMENT I.E CAPPED e S 1157 IX FIRE NYDRMT R-53 09'' L=27.14' R-60.5.8Y UTILITY EASEMENT 0e+80.17 LINGACCESS S MAD +m El0eRN0 JO'RAILROAD EASEMENT L-83.08' L-10.48' ��Q OL WAILER MEIFR o+Daro AccEss MADXr_ 30'INGRESS/Ewes EASEMENT HURL la 03' PL1A r08 woes-Lrrtn swNE 8II=LIA6'II'OA 1f0312� DL�vPE D CIS SMa rIITJt PLAN 70� LE WCDNe.-I.38 1ZII 7=0 80][�6H , x 00 _((EE}} BUSUNIM"Iff NORg'��g pLM IIEYNCM0NN1C.8.A1ga�7° is. 7YC0NC(W}ie545 )Op NO.0rQQ CONTROL SR(IEIOSIQUI.E NOM N 1YGONC.( 1574 IE tYCQIC.I(W.1�)-1152 IE I f .7254 CINSTRUCTORFLOW6,30 10.02 0`ARFLOW E1r10.70 BASIN NO. 2 ' DEVELOPED OFF SITE AREA BYPASSING BASIN = 0.20 ACRES ' TOTAL AREA OF PROJECT SITE:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.63 ACRES DRAINAGE AREA MAP LESS BYPASS AREA. . . . . . . . . . . . . . . . . . 0.06 ACRES FOR ' TOTAL AREA OF PROJECT SITE TRIBUTARY TO DETENTION BASIN . . . . . . . . . . . . 5.58 ACRES PLUS OFFSITE AREAS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.43 ACRES FARWEST STEEL TOTAL AREA TRIBUTARY TO DETENTION BASIN. . . . . . . . . . . . . . . . . . . . . . . . . 6.01 ACRES SCALE: 1" ■ 100'