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13-23 Storm Water Management Reportf9 R O U P Storm Water Management Report Project: Chanhassen Gateway 7905 Great Plains Blvd Chanhassen, MN 55317 Prepared for: NHH Chanhassen Partners, LLC Camelot Convenience & Quality Fuel & Food. All plans and supporting Documentation contained in this report have been reviewed and approved by the Registered Engineer listed below and it is hereby certified that the plans comply with the requirements of the ordinance. I hereby certify that this report was prepared by me or under my direct supervision and that I am a duly Registered Professional Engineer under the laws of the State of Minnesota. Matthew R. Pavek P.E. Registration Number: 44263 Date: 10/4/2013 Civil Site Group, Inc. 4931 West 351" Street, Suite 200, St. Louis Park, MN 55416 www.civilsitegroup.com - mpavek @civilsitegroup.com - 763.213.3944 direct 1-2 R G R O U P Table of Contents: Cover Sheet Summary Narrative Calculations Volume Retention Calculations HydroCAD Summary Table Hydraulic /Hydrologic Data Hydrocad Calculations covff(-]0Iile G R O U P Summary Narrative: This Storm Water Management Report accompanies the Civil Plans prepared for Chanhassen Gateway dated 10/4/2013 and attached to this report. Existing Site Conditions: The existing site area is 49,414 SF of commercial property containing a parking lot and Gas Station building. The existing site is approximately 50% impervious surface. Approximately 70% of the existing gas station site drains via storm sewer pipes to storm sewer located in Great Plains Boulevard. The remaining 30% drains overland to catch basins along Highway 5. Proposed Site: The proposed project is the redevelopment of the gas station site into a retail building and parking lot. Landscape areas, a rain garden and other pervious surfaces will be added as a part of this project. Drainage patterns will not change. Time of Concentration is assumed at 10 minutes. Requirements: Per City of Chanhassen Rate Control: Provide rate control to existing conditions for the site. Proposed Storm Water Facilities: Rate, Volume & Quality Control practices proposed: Infiltration Basin / Rain Garden: Approximately 30% of the site including new impervious area drains to the proposed rain garden area. This basin is designed with a water quality volume (volume below the outlet) of 755 Cubic Feet. The volume of runoff from 1" over the new impervious area of the project is (10,059SF x 1'� = 840 CF. The proposed rain garden essentially provides infiltration /filtration for 90% of the 1" runoff generated by the new impervious surfaces of this project. This is not required, but provided. Rate control for the project is also provided by the proposed rain garden to the extent practical with the size rain garden feasible for the open space on the site. Runoff rates are (—J J I 1V1 Elie G R O U P less than existing for the 2 -year event, and slightly more for the 10 & 100- year event. See the table below for the pre and post runoff rates for this project. Rate Control Summary Table: STORM EVENT EXISTING RUNOFF (CFS) PROPOSED RUNOFF CFS 2 -YEAR 2.80 2.63 10 -YEAR 4.88 5.33 100 -YEAR 7.56 7.96 MM47 b1 o TrCW%VM. No NO R w wnc6 EXISTING SITE Subcat Reach on Link CHAN BP Prepared by Microsoft EXISTING Type 11 24 -hr 2 -YEAR Rainfall= 2.80" Printed 10/7/2013 Summary for Subcatchment 1S: EXISTING SITE Runoff = 2.80 cfs @ 12.01 hrs, Volume= 0.155 af, Depth> 1.64" Runoff by SCS TR -20 method, UH =SCS, Weighted -CN, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type II 24 -hr 2 -YEAR Rainfall= 2.80" Area (sf) CN Description * 1,831 98 BUILDING * 21,310 98 PAVEMENT * 26,273 80 LANDSCAPE 49,414 88 Weighted Average 26,273 53.17% Pervious Area 23,141 46.83% Impervious Area Tc Length Slope 10.0 Description Direct Entry, CHAN BP Prepared by Microsoft HvdroCAD® 10.00 s/n 02 EXISTING Type 1124 -hr 10 -YR Rainfall= 4.20" Printed 10/7/2013 Summary for Subcatchment 1S: EXISTING SITE Runoff = 4.88 cfs @ 12.01 hrs, Volume= 0.275 af, Depth> 2.91" Runoff by SCS TR -20 method, UH =SCS, Weighted -CN, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type II 24 -hr 10 -YR Rainfall= 4.20" Area (sf) CN Description * 1,831 98 BUILDING * 21,310 98 PAVEMENT * 26,273 80 LANDSCAPE 49,414 88 Weighted Average 26,273 53.17% Pervious Area 23,141 46.83% Impervious Area Tc Length 10.0 Description Direct Entry, CHAN BP Prepared by Microsoft HvdroCAD® 10.00 s/n 02202 © 2013 EXISTING Type 1124 -hr 100 -YR Rainfall = 6.00" Printed 10/7/2013 Summary for Subcatchment 1S: EXISTING SITE Runoff = 7.56 cfs @ 12.01 hrs, Volume= 0.437 af, Depth> 4.62" Runoff by SCS TR -20 method, UH =SCS, Weighted -CN, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type II 24 -hr 100 -YR Rainfall= 6.00" Area (sf) CN Description * 1,831 98 BUILDING * 21,310 98 PAVEMENT * 26.273 80 LANDSCAPE 49,414 88 Weighted Average 26,273 53.17% Pervious Area 23,141 46.83% Impervious Area Tc Length 10.0 Description Direct Entry, 5S A PROPOSED SITE TO RAIN GARDEN RAIN GARDEN 6R U PROPOSED SITE NOT TO RAIN GARDEN Subcat Reach on Link PROPOSED SITE TOTAL PROPOSED CHAN BP Prepared by Microsoft Printed 10/7/2013 HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Page 2 Area Listing (selected nodes) Area CN Description (acres) (subcatchment- numbers) 0.240 98 BUILDING (3S) 0.372 80 LANDSCAPE (3S, 5S) 0.522 98 PAVEMENT (3S, 5S) 1.134 92 TOTAL AREA CHAN BP Prepared by Microsoft roCAD Software Solutic Soil Listing (selected nodes) Area Soil Subcatchment (acres) 0.000 0.000 0.000 0.000 1.134 1.134 Group Numbers HSG A HSG B HSG C HSG D Other 3S, 5S TOTAL AREA '[0'• 9 Printed 10/7/2013 PROPOSED CHAN BP Prepared by Microsoft Printed 10/7/2013 HydroCAD® 10.00 s/n 02202 @2013 HydroCAD Software Solutions LLC Pape 4 Ground Covers (selected nodes) HSG -A HSG -B HSG -C HSG -D Other Total Ground Subcatchment (acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers 0.000 0.000 0.000 0.000 0.240 0.240 BUILDING 3S 0.000 0.000 0.000 0.000 0.372 0.372 LANDSCAPE 3S, 5S 0.000 0.000 0.000 0.000 0.522 0.522 PAVEMENT 3S, 5S 0.000 0.000 0.000 0.000 1.134 1.134 TOTAL AREA CHAN BP Prepared by Microsoft Pipe Listing (selected nodes) PROPOSED Printed 10/7/2013 Line# Node In -Invert Out -Invert Length Slope n Diam/Width Height Inside -Fill Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches) 1 4P 951.00 950.30 26.0 0.0269 0.013 12.0 0.0 0.0 PROPOSED CHAN BP Type// 24 -hr 2 -YEAR Rainfall= 2.80" Prepared by Microsoft Printed 10/7/2013 HydroCAD® 10.00 s/n 02202 02013 HydroCAD Software Solutions LLC Page 6 Time span =0.00 -24.00 hrs, dt =0.05 hrs, 481 points Runoff by SCS TR -20 method, UH =SCS, Weighted -CN Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment3S: PROPOSED SITE NOT Runoff Area= 39,188sf 64.91% Impervious Runoff Depth >1.97" Tc=10.0 min CN =92 Runoff =2.61 cfs 0.148 of Subcatchment5S: PROPOSED SITE TO Runoff Area= 10,226 sf 75.92% Impervious Runoff Depth >2.15" Tc =10.0 min CN =94 Runoff =0.73 cfs 0.042 of Reach 6R: PROPOSED SITE TOTAL Inflow =2.63 cfs 0.178 of Outflow =2.63 cfs 0.178 of Pond 4P: RAIN GARDEN Peak Elev= 954.06' Storage =814 cf Inflow =0.73 cfs 0.042 of Outflow =0.31 cfs 0.030 of Total Runoff Area= 1.134 ac Runoff Volume= 0.190 of Average Runoff Depth =2.01" 32.81% Pervious = 0.372 ac 67.19% Impervious = 0.762 ac CHAN BP Prepared by Microsoft PROPOSED Type// 24 -hr 2 -YEAR Rainfall= 2.80" Printed 10/7/2013 Summary for Subcatchment 3S: PROPOSED SITE NOT TO RAIN GARDEN Runoff = 2.61 cfs @ 12.01 hrs, Volume= 0.148 af, Depth> 1.97' Runoff by SCS TR -20 method, UH =SCS, Weighted -CN, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type II 24 -hr 2 -YEAR Rainfall= 2.80" Area (sf) CN Description * 10,443 98 BUILDING * 14,993 98 PAVEMENT * 13,752 80 LANDSCAPE 39,188 92 Weighted Average 13,752 35.09% Pervious Area 25,436 64.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, PROPOSED CHAN BP Type// 24 -hr 2 -YEAR Rainfall = 2.80" Prepared by Microsoft Printed 10/7/2013 HydroCAD ®10.00 s/n 02202 02013 HydroCAD Software Solutions LLC Page 8 Summary for Subcatchment 5S: PROPOSED SITE TO RAIN GARDEN Runoff = 0.73 cfs @ 12.01 hrs, Volume= 0.042 af, Depth> 2.15' Runoff by SCS TR -20 method, UH =SCS, Weighted -CN, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type II 24 -hr 2 -YEAR Rainfall= 2.80" Area (sf) CN Description * 0 98 BUILDING * 7,764 98 PAVEMENT * 2,462 80 LANDSCAPE 10,226 94 Weighted Average 2,462 24.08% Pervious Area 7,764 75.92% Impervious Area Tc Length 10.0 Description Direct Entry, PROPOSED CHAN BP Type ll 24 -hr 2 -YEAR Rainfall= 2.80" Prepared by Microsoft Printed 10/7/2013 Summary for Reach 6R: PROPOSED SITE TOTAL [40] Hint: Not Described (Outflow= Inflow) Inflow Area = 1.134 ac, 67.19% Impervious, Inflow Depth > 1.88" for 2 -YEAR event Inflow = 2.63 cfs @ 12.01 hrs, Volume= 0.178 of Outflow = 2.63 cfs @ 12.01 hrs, Volume= 0.178 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs CHAN EIP Prepared by Microsoft PROPOSED Type// 24 -hr 2 -YEAR Rainfall= 2.80" Summary for Pond 4P: RAIN GARDEN Printed 10/7/2013 Inflow Area = 0.235 ac, 75.92% Impervious, Inflow Depth > 2.15" for 2 -YEAR event Inflow = 0.73 cfs @ 12.01 hrs, Volume= 0.042 of Outflow = 0.31 cfs @ 12.17 hrs, Volume= 0.030 af, Atten= 58 %, Lag= 9.7 min Primary = 0.31 cfs @ 12.17 hrs, Volume= 0.030 of Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 954.06' @ 12.17 hrs Surf.Area= 1,023 sf Storage= 814 cf Plug -Flow detention time= 220.9 min calculated for 0.030 of (71 % of inflow) Center -of -Mass det. time= 127.4 min ( 918.3 - 790.9 ) Volume Invert Avail.Storage Storage Description #1 953.00' 2,025 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 953.00 520 0 0 954.00 990 755 755 955.00 1,550 1,270 2,025 Device Routing Invert Outlet Devices #1 Primary 954.00' 24.0" Horiz. Orifice /Grate C= 0.600 Limited to weir flow at low heads #2 Primary 954.50' 5.0' long x 5.0' breadth Broad - Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #3 Primary 953.00' 0.800 in /hr Exfiltration over Surface area - A r , K«„ 50� s 'C',, v.z' #4 Device 1 951.00' 12.0" Round Culvert o•� %. „, �i. L= 26.0' RCP, square edge headwall, Ke= 0.500 Inlet/ Outlet Invert= 951.00'/ 950.30' S=0.02697' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf Primary OutFlow Max =0.27 cfs @ 12.17 hrs HW= 954.05' (Free Discharge) 11 Orifice /Grate (Weir Controls 0.26 cfs @ 0.76 fps) = Culvert (Passes 0.26 cfs of 0.88 cfs potential flow) 2= Broad- Crested Rectangular Weir( Controls 0.00 cfs) 3= Exfiltration (Exfiltration Controls 0.02 cfs) CHAN BP Prepared by Microsoft HVdroCAD ®10.00 s/n 022i PROPOSED Type// 24 -hr 10 -YR Rainfall= 4.20" Printed 10/7/2013 Time span =0.00 -24.00 hrs, dt =0.05 hrs, 481 points Runoff by SCS TR -20 method, UH =SCS, Weighted -CN Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment3S: PROPOSED SITE NOT Runoff Area = 39,188 sf 64.91% Impervious Runoff Depth >3.31" Tc =10.0 min CN =92 Runoff =4.26 cfs 0.248 of Subcatchment5S: PROPOSED SITE TO Runoff Area = 10,226 sf 75.92% Impervious Runoff Depth >3.51" Tc =10.0 min CN =94 Runoff =1.16 cfs 0.069 of Reach 6R: PROPOSED SITE TOTAL Inflow =5.33 cfs 0.302 of Outflow =5.33 cfs 0.302 of Pond 4P: RAIN GARDEN Peak Elev= 954.14' Storage =900 cf Inflow =1.16 cfs 0.069 of Outflow =1.11 cfs 0.054 of Total Runoff Area= 1.134 ac Runoff Volume= 0.317 of Average Runoff Depth =3.35" 32.81% Pervious= 0.372 ac 67.19% Impervious = 0.762 ac PROPOSED CHAN BP Type 1124 -hr 10 -YR Rainfall= 4.20" Prepared by Microsoft Printed 10/7/2013 HydroCAD® 10.00 s/n 02202 02013 HydroCAD Software Solutions LLC Page 12 Summary for Subcatchment 3S: PROPOSED SITE NOT TO RAIN GARDEN Runoff = 4.26 cfs @ 12.01 hrs, Volume= 0.248 af, Depth> 3.31" Runoff by SCS TR -20 method, UH =SCS, Weighted -CN, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type 11 24 -hr 10 -YR Rainfall= 4.20" Area (sf) CN Description * 10,443 98 BUILDING * 14,993 98 PAVEMENT * 13,752 80 LANDSCAPE 39,188 92 Weighted Average 13,752 35.09% Pervious Area 25,436 64.91% Impervious Area Tc Length 10.0 Description Direct Entry, CHAN BP Prepared by Microsoft @ 2013 PROPOSED Type 1124 -hr 10 -YR Rainfall= 4.20" Printed 10/7/2013 Summary for Subcatchment 5S: PROPOSED SITE TO RAIN GARDEN Runoff = 1.16 cfs @ 12.01 hrs, Volume= 0.069 af, Depth> 3.51" Runoff by SCS TR -20 method, UH =SCS, Weighted -CN, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type II 24 -hr 10 -YR Rainfall= 4.20" Area (sf) CN Description * 0 98 BUILDING * 7,764 98 PAVEMENT * 2,462 80 LANDSCAPE 10,226 94 Weighted Average 2,462 24.08% Pervious Area 7,764 75.92% Impervious Area Tc Length Slope 10.0 Description Direct Entry, PROPOSED CHAN BP Type 11 24 -hr 90 -YR Rainfall= 4.20" Prepared by Microsoft Printed 10/7/2013 HydroCAD ®10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Pape 14 Summary for Reach 6R: PROPOSED SITE TOTAL [40] Hint: Not Described (Outflow--inflow) Inflow Area = 1.134 ac, 67.19% Impervious, Inflow Depth > 3.19" for 10 -YR event Inflow = 5.33 cfs @ 12.02 hrs, Volume= 0.302 of Outflow = 5.33 cfs @ 12.02 hrs, Volume= 0.302 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs PROPOSED CHAN BP Type // 24 -hr 10 -YR Rainfall= 4.20" Prepared by Microsoft Printed 10/7/2013 HydroCAD® 10.00 s/n 02202 @ 2013 HydroCAD Software Solutions LLC Page 15 Summary for Pond 4P: RAIN GARDEN Inflow Area = 0.235 ac, 75.92% Impervious, Inflow Depth > 3.51" for 10 -YR event Inflow = 1.16 cfs @ 12.01 hrs, Volume= 0.069 of Outflow = 1.11 cfs @ 12.05 hrs, Volume= 0.054 af, Atten= 4 %, Lag= 2.3 min Primary = 1.11 cfs @ 12.05 hrs, Volume= 0.054 of Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 954.14' @ 12.05 hrs Surf.Area= 1,069 sf Storage= 900 cf Plug -Flow detention time= 141.1 min calculated for 0.054 of (78% of inflow) Center -of -Mass det. time= 58.9 min ( 836.6 - 777.7 ) Volume Invert Avail.Storage Storage Description #1 953.00' 2,025 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 953.00 520 0 0 954.00 990 755 755 955.00 1,550 1,270 2,025 Device Routing Invert Outlet Devices #1 Primary 954.00' 24.0" Horiz. Orifice /Grate C= 0.600 Limited to weir flow at low heads #2 Primary 954.50' 5.0' long x 5.0' breadth Broad - Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #3 Primary 953.00' 0.800 in /hr Exfiltration over Surface area #4 Device 1 951.00' 12.0" Round Culvert L= 26.0' RCP, square edge headwall, Ke= 0.500 Inlet/ Outlet Invert= 951.00'/ 950.30' S=0.0269'/' Cc= 0.900 n=0.013, Flow Area= 0.79 sf Primary OutFlow Max =1.09 cfs @ 12.05 hrs HW= 954.14' (Free Discharge) 1 Orifice /Grate (Weir Controls 1.07 cfs @ 1.22 fps) �4= Culvert (Passes 1.07 cfs of 1.41 cfs potential flow) 2= Broad- Crested Rectangular Weir( Controls 0.00 cfs) 3= Exfiltration (Exfiltration Controls 0.02 cfs) PROPOSED CHAN BP Type 1124 -hr 100 -YR Rainfall= 6.00" Prepared by Microsoft Printed 10/7/2013 HydroCAD ®10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Page 16 Time span =0.00 -24.00 hrs, dt =0.05 hrs, 481 points Runoff by SCS TR -20 method, UH =SCS, Weighted -CN Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment3S: PROPOSED SITE NOT Runoff Area = 39,188 sf 64.91% Impervious Runoff Depth >5.06" Tc =10.0 min CN =92 Runoff =6.36 cfs 0.379 of Subcatchment5S: PROPOSED SITE TO Runoff Area= 10,226 sf 75.92% Impervious Runoff Depth >5.29" Tc =10.0 min CN =94 Runoff =1.70 cfs 0.103 of Reach 6R: PROPOSED SITE TOTAL Inflow =7.96 cfs 0.466 of Outflow =7.96 cfs 0.466 of Pond 4P: RAIN GARDEN Peak Elev= 954.19' Storage =948 cf Inflow =1.70 cfs 0.103 of Outflow =1.64 cfs 0.087 of Total Runoff Area= 1.134 ac Runoff Volume= 0.483 of Average Runoff Depth= 5.11" 32.81% Pervious= 0.372 ac 67.19% Impervious= 0.762 ac PROPOSED CHAN BP Type// 24 -hr 100 -YR Rainfall= 6.00" Prepared by Microsoft Printed 10/7/2013 HydroCAD® 10.00 s/n 02202 @2013 HydroCAD Software Solutions LLC Page 17 Summary for Subcatchment 3S: PROPOSED SITE NOT TO RAIN GARDEN Runoff = 6.36 cfs @ 12.01 hrs, Volume= 0.379 af, Depth> 5.06" Runoff by SCS TR -20 method, UH =SCS, Weighted -CN, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type II 24 -hr 100 -YR Rainfall = 6.00" Area (sf) CN Description * 10,443 98 BUILDING * 14,993 98 PAVEMENT * 13,752 80 LANDSCAPE 39,188 92 Weighted Average 13,752 35.09% Pervious Area 25,436 64.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, PROPOSED CHAN BP Type 1124 -hr 100 -YR Rainfall= 6.00" Prepared by Microsoft Printed 10/7/2013 HydroCAD ®10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Page 18 Summary for Subcatchment 5S: PROPOSED SITE TO RAIN GARDEN Runoff = 1.70 cfs @ 12.01 hrs, Volume= 0.103 af, Depth> 5.29" Runoff by SCS TR -20 method, UH =SCS, Weighted -CN, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Type II 24 -hr 100 -YR Rainfall= 6.00" Area (sf) CN Description * 0 98 BUILDING * 7,764 98 PAVEMENT * 2,462 80 LANDSCAPE 10,226 94 Weighted Average 2,462 24.08% Pervious Area 7,764 75.92% Impervious Area Tc Length MI R Description Direct Entry, CHAN BP Prepared by Microsoft HvdroCAD@ 10.00 s/n 02202 02013 PROPOSED Type 1124-hr 100 -YR Rainfall = 6.00" Printed 10/7/2013 Summary for Reach 6R: PROPOSED SITE TOTAL [40] Hint: Not Described (Outflow= Inflow) Inflow Area = 1.134 ac, 67.19% Impervious, Inflow Depth > 4.93" for 100 -YR event Inflow = 7.96 cfs @ 12.01 hrs, Volume= 0.466 of Outflow = 7.96 cfs @ 12.01 hrs, Volume= 0.466 af, Atten= 0 %, Lag= 0.0 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs CHAN BP Prepared by Microsoft PROPOSED Type 1124 -hr 100 -YR Rainfall = 6.00" Printed 10/7/2013 Summary for Pond 4P: RAIN GARDEN Inflow Area = 0.235 ac, 75.92% Impervious, Inflow Depth > 5.29" for 100 -YR event Inflow = 1.70 cfs @ 12.01 hrs, Volume= 0.103 of Outflow = 1.64 cfs @ 12.03 hrs, Volume= 0.087 af, Atten= 4 %, Lag= 1.4 min Primary = 1.64 cfs @ 12.03 hrs, Volume= 0.087 of Routing by Stor -Ind method, Time Span= 0.00 -24.00 hrs, dt= 0.05 hrs Peak Elev= 954.19' @ 12.03 hrs Surf.Area= 1,094 sf Storage= 948 cf Plug -Flow detention time= 104.9 min calculated for 0.086 of (83% of inflow) Center -of -Mass det. time= 35.0 min ( 802.5 - 767.5 ) Volume Invert Avail.Storage Storage Description #1 953.00' 2,025 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 953.00 520 0 0 954.00 990 755 755 955.00 1,550 1,270 2,025 Device Routing Invert Outlet Devices #1 Primary 954.00' 24.0" Horiz. Orifice /Grate C= 0.600 Limited to weir flow at low heads #2 Primary 954.50' 5.0' long x 5.0' breadth Broad - Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #3 Primary 953.00' 0.800 in /hr Exfiltration over Surface area #4 Device 1 951.00' 12.0" Round Culvert L= 26.0' RCP, square edge headwall, Ke= 0.500 Inlet/ Outlet Invert= 951.00'/950.30' S=0.0269'/' Cc= 0.900 n=0.013, Flow Area= 0.79 sf Primary OutFlow Max =1.62 cfs @ 12.03 hrs HW= 954.18' (Free Discharge) = Orifice /Grate (Weir Controls 1.60 cfs @ 1.40 fps) = Culvert (Passes 1.60 cfs of 1.61 cfs potential flow) 2= Broad- Crested Rectangular Weir( Controls 0.00 cfs) 3= Exfiltration (Exfiltration Controls 0.02 cfs)