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Stormwater Report 10-04-2013 Civil Site Group, Inc. 4931 West 35th Street, Suite 200, St. Louis Park, MN 55416 www.civilsitegroup.com - mpavek@civilsitegroup.com - 763.213.3944 direct 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 Table of Contents: Cover Sheet Summary Narrative Calculations Volume Retention Calculations HydroCAD Summary Table Hydraulic/Hydrologic Data Hydrocad Calculations 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 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 1S EXISTING SITE Routing Diagram for CHAN BP Prepared by Microsoft, Printed 10/7/2013 HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Subcat Reach Pond Link EXISTING Type II 24-hr 2-YEAR Rainfall=2.80"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 2HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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)CNDescription *1,83198BUILDING *21,31098PAVEMENT *26,27380LANDSCAPE 49,41488Weighted Average 26,27353.17% Pervious Area 23,14146.83% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 10.0 Direct Entry, EXISTING Type II 24-hr 10-YR Rainfall=4.20"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 3HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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)CNDescription *1,83198BUILDING *21,31098PAVEMENT *26,27380LANDSCAPE 49,41488Weighted Average 26,27353.17% Pervious Area 23,14146.83% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 10.0 Direct Entry, EXISTING Type II 24-hr 100-YR Rainfall=6.00"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 4HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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)CNDescription *1,83198BUILDING *21,31098PAVEMENT *26,27380LANDSCAPE 49,41488Weighted Average 26,27353.17% Pervious Area 23,14146.83% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 10.0 Direct Entry, 3S PROPOSED SITE NOT TO RAIN GARDEN 5S PROPOSED SITE TO RAIN GARDEN 6R PROPOSED SITE TOTAL 4P RAIN GARDEN Routing Diagram for CHAN BP Prepared by Microsoft, Printed 10/7/2013 HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Subcat Reach Pond Link PROPOSED CHAN BP Printed 10/7/2013Prepared by Microsoft Page 2HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Area Listing (selected nodes) Area (acres) CNDescription (subcatchment-numbers) 0.24098BUILDING (3S) 0.37280LANDSCAPE (3S, 5S) 0.52298PAVEMENT (3S, 5S) 1.13492TOTAL AREA PROPOSED CHAN BP Printed 10/7/2013Prepared by Microsoft Page 3HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Soil Listing (selected nodes) Area (acres) Soil Group Subcatchment Numbers 0.000HSG A 0.000HSG B 0.000HSG C 0.000HSG D 1.134Other3S, 5S 1.134TOTAL AREA PROPOSED CHAN BP Printed 10/7/2013Prepared by Microsoft Page 4HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Ground Covers (selected nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.0000.0000.0000.0000.2400.240BUILDING3S 0.0000.0000.0000.0000.3720.372LANDSCAPE3S, 5S 0.0000.0000.0000.0000.5220.522PAVEMENT3S, 5S 0.0000.0000.0000.0001.1341.134TOTAL AREA PROPOSED CHAN BP Printed 10/7/2013Prepared by Microsoft Page 5HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Pipe Listing (selected nodes) Line#Node Number In-Invert (feet) Out-Invert (feet) Length (feet) Slope (ft/ft) nDiam/Width (inches) Height (inches) Inside-Fill (inches) 14P951.00950.3026.00.02690.01312.00.00.0 PROPOSED Type II 24-hr 2-YEAR Rainfall=2.80"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 6HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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 Runoff Area=39,188 sf 64.91% Impervious Runoff Depth>1.97"Subcatchment 3S: PROPOSED SITE NOT Tc=10.0 min CN=92 Runoff=2.61 cfs 0.148 af Runoff Area=10,226 sf 75.92% Impervious Runoff Depth>2.15"Subcatchment 5S: PROPOSED SITE TO Tc=10.0 min CN=94 Runoff=0.73 cfs 0.042 af Inflow=2.63 cfs 0.178 afReach 6R: PROPOSED SITE TOTAL Outflow=2.63 cfs 0.178 af Peak Elev=954.06' Storage=814 cf Inflow=0.73 cfs 0.042 afPond 4P: RAIN GARDEN Outflow=0.31 cfs 0.030 af Total Runoff Area = 1.134 ac Runoff Volume = 0.190 af Average Runoff Depth = 2.01" 32.81% Pervious = 0.372 ac 67.19% Impervious = 0.762 ac PROPOSED Type II 24-hr 2-YEAR Rainfall=2.80"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 7HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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)CNDescription *10,44398BUILDING *14,99398PAVEMENT *13,75280LANDSCAPE 39,18892Weighted Average 13,75235.09% Pervious Area 25,43664.91% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 10.0 Direct Entry, PROPOSED Type II 24-hr 2-YEAR Rainfall=2.80"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 8HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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)CNDescription *098BUILDING *7,76498PAVEMENT *2,46280LANDSCAPE 10,22694Weighted Average 2,46224.08% Pervious Area 7,76475.92% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 10.0 Direct Entry, PROPOSED Type II 24-hr 2-YEAR Rainfall=2.80"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 9HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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 af 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 PROPOSED Type II 24-hr 2-YEAR Rainfall=2.80"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 10HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC Summary for Pond 4P: RAIN GARDEN 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 af 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 af 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 af (71% of inflow) Center-of-Mass det. time= 127.4 min ( 918.3 - 790.9 ) VolumeInvertAvail.StorageStorage Description #1953.00'2,025 cf Custom Stage Data (Prismatic) Listed below (Recalc) ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 953.0052000 954.00990755755 955.001,5501,2702,025 DeviceRouting InvertOutlet Devices #1Primary954.00'24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2Primary954.50'5.0' 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 #3Primary953.00'0.800 in/hr Exfiltration over Surface area #4Device 1951.00'12.0" 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=0.27 cfs @ 12.17 hrs HW=954.05' (Free Discharge) 1=Orifice/Grate (Weir Controls 0.26 cfs @ 0.76 fps) 4=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) PROPOSED Type II 24-hr 10-YR Rainfall=4.20"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 11HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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 Runoff Area=39,188 sf 64.91% Impervious Runoff Depth>3.31"Subcatchment 3S: PROPOSED SITE NOT Tc=10.0 min CN=92 Runoff=4.26 cfs 0.248 af Runoff Area=10,226 sf 75.92% Impervious Runoff Depth>3.51"Subcatchment 5S: PROPOSED SITE TO Tc=10.0 min CN=94 Runoff=1.16 cfs 0.069 af Inflow=5.33 cfs 0.302 afReach 6R: PROPOSED SITE TOTAL Outflow=5.33 cfs 0.302 af Peak Elev=954.14' Storage=900 cf Inflow=1.16 cfs 0.069 afPond 4P: RAIN GARDEN Outflow=1.11 cfs 0.054 af Total Runoff Area = 1.134 ac Runoff Volume = 0.317 af Average Runoff Depth = 3.35" 32.81% Pervious = 0.372 ac 67.19% Impervious = 0.762 ac PROPOSED Type II 24-hr 10-YR Rainfall=4.20"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 12HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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 II 24-hr 10-YR Rainfall=4.20" Area (sf)CNDescription *10,44398BUILDING *14,99398PAVEMENT *13,75280LANDSCAPE 39,18892Weighted Average 13,75235.09% Pervious Area 25,43664.91% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 10.0 Direct Entry, PROPOSED Type II 24-hr 10-YR Rainfall=4.20"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 13HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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)CNDescription *098BUILDING *7,76498PAVEMENT *2,46280LANDSCAPE 10,22694Weighted Average 2,46224.08% Pervious Area 7,76475.92% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 10.0 Direct Entry, PROPOSED Type II 24-hr 10-YR Rainfall=4.20"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 14HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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 af 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 Type II 24-hr 10-YR Rainfall=4.20"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 15HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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 af 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 af 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 af (78% of inflow) Center-of-Mass det. time= 58.9 min ( 836.6 - 777.7 ) VolumeInvertAvail.StorageStorage Description #1953.00'2,025 cf Custom Stage Data (Prismatic) Listed below (Recalc) ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 953.0052000 954.00990755755 955.001,5501,2702,025 DeviceRouting InvertOutlet Devices #1Primary954.00'24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2Primary954.50'5.0' 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 #3Primary953.00'0.800 in/hr Exfiltration over Surface area #4Device 1951.00'12.0" 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 Type II 24-hr 100-YR Rainfall=6.00"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 16HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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 Runoff Area=39,188 sf 64.91% Impervious Runoff Depth>5.06"Subcatchment 3S: PROPOSED SITE NOT Tc=10.0 min CN=92 Runoff=6.36 cfs 0.379 af Runoff Area=10,226 sf 75.92% Impervious Runoff Depth>5.29"Subcatchment 5S: PROPOSED SITE TO Tc=10.0 min CN=94 Runoff=1.70 cfs 0.103 af Inflow=7.96 cfs 0.466 afReach 6R: PROPOSED SITE TOTAL Outflow=7.96 cfs 0.466 af Peak Elev=954.19' Storage=948 cf Inflow=1.70 cfs 0.103 afPond 4P: RAIN GARDEN Outflow=1.64 cfs 0.087 af Total Runoff Area = 1.134 ac Runoff Volume = 0.483 af Average Runoff Depth = 5.11" 32.81% Pervious = 0.372 ac 67.19% Impervious = 0.762 ac PROPOSED Type II 24-hr 100-YR Rainfall=6.00"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 17HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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)CNDescription *10,44398BUILDING *14,99398PAVEMENT *13,75280LANDSCAPE 39,18892Weighted Average 13,75235.09% Pervious Area 25,43664.91% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 10.0 Direct Entry, PROPOSED Type II 24-hr 100-YR Rainfall=6.00"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 18HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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)CNDescription *098BUILDING *7,76498PAVEMENT *2,46280LANDSCAPE 10,22694Weighted Average 2,46224.08% Pervious Area 7,76475.92% Impervious Area TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 10.0 Direct Entry, PROPOSED Type II 24-hr 100-YR Rainfall=6.00"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 19HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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 af 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 PROPOSED Type II 24-hr 100-YR Rainfall=6.00"CHAN BP Printed 10/7/2013Prepared by Microsoft Page 20HydroCAD® 10.00 s/n 02202 © 2013 HydroCAD Software Solutions LLC 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 af 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 af 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 af (83% of inflow) Center-of-Mass det. time= 35.0 min ( 802.5 - 767.5 ) VolumeInvertAvail.StorageStorage Description #1953.00'2,025 cf Custom Stage Data (Prismatic) Listed below (Recalc) ElevationSurf.AreaInc.StoreCum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 953.0052000 954.00990755755 955.001,5501,2702,025 DeviceRouting InvertOutlet Devices #1Primary954.00'24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2Primary954.50'5.0' 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 #3Primary953.00'0.800 in/hr Exfiltration over Surface area #4Device 1951.00'12.0" 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) 1=Orifice/Grate (Weir Controls 1.60 cfs @ 1.40 fps) 4=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)