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HomeMy WebLinkAboutWPO202200009 Calculations WPO VSMP 2023-03-01Mountain View Elementary School COUNTY OF ALBEMARLE, VIRGINIA VSMP DESIGN CALCULATIONS & NARRATIVE MARCH 11, 2022 REVISED MAY 20, 2022 REVISED JULY 21, 2022 REVISED MARCH 1, 2023 Prepared by: Craig Kotarski, PE Timmons Group 608 Preston Ave, Suite 200 Charlottesville, VA 22903 434.327.1688 3/1/2023 Table of Contents Section Title 1 Project Narrative 2 Pipe and Inlet Computations 3 Virginia Runoff Reduction Method Worksheet Summary 4 Pre-Developed HydroCAD Calculations 5 Post-Developed HydroCAD Calculations 6 Nutrient Credit Availability Letter ONLY REVISED AREA, OUTFALL 1, INCLUDED Project Narrative: This project includes the construction of classroom additions, cafeteria expansion, additional parking, and associated utilities and site work. Other improvements include new play areas and revisions to the bus loop and care drop off loop. Water Quality Compliance: The project will have a disturbed area of 3.96 acres. Since an existing bioretention facility is being removed for the parking expansion, the limits of disturbance and land cover prior to its design and construction in 2006 is used as the pre-condition for drainage area 4. However, the adjacent existing bioretention facility designed in 2021 through lor 2 to SDP200500113 plan is to remain, and the drainage area to it was removed from the disturbed area. Information on the existing bioretention facilities can be found in 2021 letter of revision 2 to SDP200500113 and SDP200600001. Therefore, a disturbed area of 4.96 acres was used for the water quality analysis. In the proposed condition there will be 2.63 acres of managed turf, and 2.33 acres of impervious cover. Per the vrrm spread sheet required reduction in tp is 2.19 lb/yr. The remaining bioretention removes 0.21 lb/yr of phosphorus. The remaining required phosphorus removal is 1.98 lb/yr. All 1.98 lb/yr will be purchased from an offsite nutrient credit bank. Water Quantity Compliance: Stormwater Quantity requirements for analysis point 1 are met utilizing a CMP detention system located within the turnaround. Drainage Area 2 and Drainage Area 5 have a reduction in area and remain as sheet flow in the post condition. In accordance with section 9VAC25-870-66D, all increased sheet flow from the site has been analyzed and found to cause no erosion, sedimentation, flooding, or damage to down-gradient properties or resources thus no further quantity controls are required. As for analysis point 4, channel and flood protection requirements are satisfied using a new dry pond. 1S Post DA 1A - Disturbed/Detained 2S Post DA 1B - Disturbed/Undetained 3S Post DA 1C - Undisturbed/Detained 4S Post DA 2 - Disturbed 8S Post DA 4A - Disturbed 9S Post DA 4B - Undisturbed 10S Post DA 5 - Disturbed 4P CMP #1 7P Dry Pond 4L Post Outfall 4 5P Post Outfall 1 Routing Diagram for Post Dev Prepared by Timmons Group, Printed 5/20/2022 HydroCAD® 10.10-4a s/n 08663 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 1yr Rainfall=3.04"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Post DA 1A - Disturbed/Detained Runoff =2.47 cfs @ 11.97 hrs, Volume=0.114 af, Depth>1.88" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1yr Rainfall=3.04" Area (ac)CN Description 0.470 98 Paved parking, HSG B 0.160 61 >75% Grass cover, Good, HSG B *0.099 98 New Classroom Trailer 0.729 90 Weighted Average 0.160 21.95% Pervious Area 0.569 78.05% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 1S: Post DA 1A - Disturbed/Detained Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)2 1 0 Type II 24-hr 1yr Rainfall=3.04" Runoff Area=0.729 ac Runoff Volume=0.114 af Runoff Depth>1.88" Tc=6.0 min CN=90 2.47 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type II 24-hr 1yr Rainfall=3.04"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Post DA 1B - Disturbed/Undetained Runoff =0.30 cfs @ 11.96 hrs, Volume=0.014 af, Depth>2.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1yr Rainfall=3.04" Area (ac)CN Description 0.070 98 Paved parking, HSG B 0.010 61 >75% Grass cover, Good, HSG B 0.080 93 Weighted Average 0.010 12.50% Pervious Area 0.070 87.50% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 2S: Post DA 1B - Disturbed/Undetained Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type II 24-hr 1yr Rainfall=3.04" Runoff Area=0.080 ac Runoff Volume=0.014 af Runoff Depth>2.15" Tc=6.0 min CN=93 0.30 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type II 24-hr 1yr Rainfall=3.04"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Post DA 1C - Undisturbed/Detained Runoff =0.21 cfs @ 11.97 hrs, Volume=0.010 af, Depth>1.43" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1yr Rainfall=3.04" Area (ac)CN Description 0.050 98 Paved parking, HSG B 0.030 61 >75% Grass cover, Good, HSG B 0.080 84 Weighted Average 0.030 37.50% Pervious Area 0.050 62.50% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 3S: Post DA 1C - Undisturbed/Detained Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.23 0.22 0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type II 24-hr 1yr Rainfall=3.04" Runoff Area=0.080 ac Runoff Volume=0.010 af Runoff Depth>1.43" Tc=6.0 min CN=84 0.21 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type II 24-hr 1yr Rainfall=3.04"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Pond 4P: CMP #1 Inflow Area =0.809 ac,76.51% Impervious, Inflow Depth > 1.84" for 1yr event Inflow =2.68 cfs @ 11.97 hrs, Volume=0.124 af Outflow =0.62 cfs @ 12.13 hrs, Volume=0.123 af, Atten= 77%, Lag= 10.0 min Primary =0.62 cfs @ 12.13 hrs, Volume=0.123 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 575.67' @ 12.13 hrs Surf.Area= 1,531 sf Storage= 1,911 cf Plug-Flow detention time= 31.6 min calculated for 0.123 af (99% of inflow) Center-of-Mass det. time= 28.3 min ( 798.3 - 770.0 ) Volume Invert Avail.Storage Storage Description #1 574.10'3,612 cf 36.0" Round Pipe Storage PLUS 55' for trailer L= 511.0' Device Routing Invert Outlet Devices #1 Primary 574.10'12.0" Round Culvert L= 100.0' CMP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 574.10' / 573.60' S= 0.0050 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf #2 Device 1 574.10'4.5" Vert. Orifice/Grate C= 0.600 #3 Device 1 575.75'10.5" W x 10.5" H Vert. Orifice/Grate C= 0.600 #4 Device 1 576.76'1.8' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=0.62 cfs @ 12.13 hrs HW=575.67' (Free Discharge) 1=Culvert (Passes 0.62 cfs of 3.02 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.62 cfs @ 5.65 fps) 3=Orifice/Grate ( Controls 0.00 cfs) 4=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) Pond 4P: CMP #1 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)3 2 1 0 Inflow Area=0.809 ac Peak Elev=575.67' Storage=1,911 cf 2.68 cfs 0.62 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type II 24-hr 1yr Rainfall=3.04"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Link 5P: Post Outfall 1 Inflow Area =0.889 ac,77.50% Impervious, Inflow Depth > 1.85" for 1yr event Inflow =0.85 cfs @ 12.00 hrs, Volume=0.137 af Primary =0.85 cfs @ 12.00 hrs, Volume=0.137 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Link 5P: Post Outfall 1 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.889 ac 0.85 cfs 0.85 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type II 24-hr 2 Rainfall=3.68"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Post DA 1A - Disturbed/Detained Runoff =3.15 cfs @ 11.97 hrs, Volume=0.149 af, Depth>2.45" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2 Rainfall=3.68" Area (ac)CN Description 0.470 98 Paved parking, HSG B 0.160 61 >75% Grass cover, Good, HSG B *0.099 98 New Classroom Trailer 0.729 90 Weighted Average 0.160 21.95% Pervious Area 0.569 78.05% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 1S: Post DA 1A - Disturbed/Detained Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)3 2 1 0 Type II 24-hr 2 Rainfall=3.68" Runoff Area=0.729 ac Runoff Volume=0.149 af Runoff Depth>2.45" Tc=6.0 min CN=90 3.15 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type II 24-hr 2 Rainfall=3.68"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Post DA 1B - Disturbed/Undetained Runoff =0.37 cfs @ 11.96 hrs, Volume=0.018 af, Depth>2.73" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2 Rainfall=3.68" Area (ac)CN Description 0.070 98 Paved parking, HSG B 0.010 61 >75% Grass cover, Good, HSG B 0.080 93 Weighted Average 0.010 12.50% Pervious Area 0.070 87.50% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 2S: Post DA 1B - Disturbed/Undetained Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type II 24-hr 2 Rainfall=3.68" Runoff Area=0.080 ac Runoff Volume=0.018 af Runoff Depth>2.73" Tc=6.0 min CN=93 0.37 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type II 24-hr 2 Rainfall=3.68"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Post DA 1C - Undisturbed/Detained Runoff =0.29 cfs @ 11.97 hrs, Volume=0.013 af, Depth>1.94" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2 Rainfall=3.68" Area (ac)CN Description 0.050 98 Paved parking, HSG B 0.030 61 >75% Grass cover, Good, HSG B 0.080 84 Weighted Average 0.030 37.50% Pervious Area 0.050 62.50% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 3S: Post DA 1C - Undisturbed/Detained Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type II 24-hr 2 Rainfall=3.68" Runoff Area=0.080 ac Runoff Volume=0.013 af Runoff Depth>1.94" Tc=6.0 min CN=84 0.29 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type II 24-hr 2 Rainfall=3.68"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Pond 4P: CMP #1 Inflow Area =0.809 ac,76.51% Impervious, Inflow Depth > 2.40" for 2 event Inflow =3.44 cfs @ 11.97 hrs, Volume=0.162 af Outflow =1.14 cfs @ 12.11 hrs, Volume=0.160 af, Atten= 67%, Lag= 8.4 min Primary =1.14 cfs @ 12.11 hrs, Volume=0.160 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 576.04' @ 12.11 hrs Surf.Area= 1,466 sf Storage= 2,469 cf Plug-Flow detention time= 32.7 min calculated for 0.160 af (99% of inflow) Center-of-Mass det. time= 29.6 min ( 793.5 - 763.9 ) Volume Invert Avail.Storage Storage Description #1 574.10'3,612 cf 36.0" Round Pipe Storage PLUS 55' for trailer L= 511.0' Device Routing Invert Outlet Devices #1 Primary 574.10'12.0" Round Culvert L= 100.0' CMP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 574.10' / 573.60' S= 0.0050 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf #2 Device 1 574.10'4.5" Vert. Orifice/Grate C= 0.600 #3 Device 1 575.75'10.5" W x 10.5" H Vert. Orifice/Grate C= 0.600 #4 Device 1 576.76'1.8' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=1.13 cfs @ 12.11 hrs HW=576.03' (Free Discharge) 1=Culvert (Passes 1.13 cfs of 3.50 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.70 cfs @ 6.36 fps) 3=Orifice/Grate (Orifice Controls 0.42 cfs @ 1.71 fps) 4=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) Pond 4P: CMP #1 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)3 2 1 0 Inflow Area=0.809 ac Peak Elev=576.04' Storage=2,469 cf 3.44 cfs 1.14 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type II 24-hr 2 Rainfall=3.68"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Link 5P: Post Outfall 1 Inflow Area =0.889 ac,77.50% Impervious, Inflow Depth > 2.41" for 2 event Inflow =1.26 cfs @ 12.08 hrs, Volume=0.179 af Primary =1.26 cfs @ 12.08 hrs, Volume=0.179 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Link 5P: Post Outfall 1 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)1 0 Inflow Area=0.889 ac 1.26 cfs 1.26 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type II 24-hr 10 yr Rainfall=5.57"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Post DA 1A - Disturbed/Detained Runoff =5.17 cfs @ 11.96 hrs, Volume=0.252 af, Depth>4.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr Rainfall=5.57" Area (ac)CN Description 0.470 98 Paved parking, HSG B 0.160 61 >75% Grass cover, Good, HSG B *0.099 98 New Classroom Trailer 0.729 90 Weighted Average 0.160 21.95% Pervious Area 0.569 78.05% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 1S: Post DA 1A - Disturbed/Detained Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)5 4 3 2 1 0 Type II 24-hr 10 yr Rainfall=5.57" Runoff Area=0.729 ac Runoff Volume=0.252 af Runoff Depth>4.15" Tc=6.0 min CN=90 5.17 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type II 24-hr 10 yr Rainfall=5.57"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: Post DA 1B - Disturbed/Undetained Runoff =0.59 cfs @ 11.96 hrs, Volume=0.030 af, Depth>4.45" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr Rainfall=5.57" Area (ac)CN Description 0.070 98 Paved parking, HSG B 0.010 61 >75% Grass cover, Good, HSG B 0.080 93 Weighted Average 0.010 12.50% Pervious Area 0.070 87.50% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 2S: Post DA 1B - Disturbed/Undetained Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type II 24-hr 10 yr Rainfall=5.57" Runoff Area=0.080 ac Runoff Volume=0.030 af Runoff Depth>4.45" Tc=6.0 min CN=93 0.59 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type II 24-hr 10 yr Rainfall=5.57"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: Post DA 1C - Undisturbed/Detained Runoff =0.51 cfs @ 11.97 hrs, Volume=0.024 af, Depth>3.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr Rainfall=5.57" Area (ac)CN Description 0.050 98 Paved parking, HSG B 0.030 61 >75% Grass cover, Good, HSG B 0.080 84 Weighted Average 0.030 37.50% Pervious Area 0.050 62.50% Impervious Area Tc Length Slope Velocity Capacity Description (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 3S: Post DA 1C - Undisturbed/Detained Runoff Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type II 24-hr 10 yr Rainfall=5.57" Runoff Area=0.080 ac Runoff Volume=0.024 af Runoff Depth>3.54" Tc=6.0 min CN=84 0.51 cfs This document was created by an application that isn’t licensed to use novaPDF. 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Type II 24-hr 10 yr Rainfall=5.57"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Pond 4P: CMP #1 Inflow Area =0.809 ac,76.51% Impervious, Inflow Depth > 4.09" for 10 yr event Inflow =5.67 cfs @ 11.96 hrs, Volume=0.276 af Outflow =3.83 cfs @ 12.05 hrs, Volume=0.274 af, Atten= 33%, Lag= 4.9 min Primary =3.83 cfs @ 12.05 hrs, Volume=0.274 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 576.83' @ 12.05 hrs Surf.Area= 883 sf Storage= 3,447 cf Plug-Flow detention time= 27.9 min calculated for 0.274 af (99% of inflow) Center-of-Mass det. time= 25.2 min ( 777.7 - 752.5 ) Volume Invert Avail.Storage Storage Description #1 574.10'3,612 cf 36.0" Round Pipe Storage PLUS 55' for trailer L= 511.0' Device Routing Invert Outlet Devices #1 Primary 574.10'12.0" Round Culvert L= 100.0' CMP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 574.10' / 573.60' S= 0.0050 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf #2 Device 1 574.10'4.5" Vert. Orifice/Grate C= 0.600 #3 Device 1 575.75'10.5" W x 10.5" H Vert. Orifice/Grate C= 0.600 #4 Device 1 576.76'1.8' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=3.77 cfs @ 12.05 hrs HW=576.81' (Free Discharge) 1=Culvert (Passes 3.77 cfs of 4.35 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.85 cfs @ 7.65 fps) 3=Orifice/Grate (Orifice Controls 2.85 cfs @ 3.73 fps) 4=Sharp-Crested Rectangular Weir (Weir Controls 0.08 cfs @ 0.77 fps) Pond 4P: CMP #1 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)6 5 4 3 2 1 0 Inflow Area=0.809 ac Peak Elev=576.83' Storage=3,447 cf 5.67 cfs 3.83 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Type II 24-hr 10 yr Rainfall=5.57"SPA_Post Dev-w_Trailer Printed 2/28/2023Prepared by TIMMONS GROUP HydroCAD® 10.00-19 s/n 06538 © 2016 HydroCAD Software Solutions LLC Summary for Link 5P: Post Outfall 1 Inflow Area =0.889 ac,77.50% Impervious, Inflow Depth > 4.10" for 10 yr event Inflow =4.20 cfs @ 12.04 hrs, Volume=0.304 af Primary =4.20 cfs @ 12.04 hrs, Volume=0.304 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Link 5P: Post Outfall 1 Inflow Primary Hydrograph Time (hours) 201918171615141312111098765Flow (cfs)4 3 2 1 0 Inflow Area=0.889 ac 4.20 cfs 4.20 cfs This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice.