1240815StormWaterManagementReport

PLEASANT VALLEY WAY 1240815-pipes NOAA 24-hr D 100-Year-2020 Rainfall=9.18", P2=3.47" Prepared by Casey & Keller, Inc Printed 9/12/2025 HydroCAD® 10.20-7a s/n 03272 © 2025 HydroCAD Software Solutions LLC Summary for Pond 5: Pipes Inflow Area = 0.359 ac, 71.75% Impervious, Inflow Depth = 4.98" for 100-Year-2020 event Inflow = 2.19 cfs @ 12.07 hrs, Volume= 0.149 af Outflow = 1.83 cfs @ 12.15 hrs, Volume= 0.149 af, Atten= 16%, Lag= 4.6 min Discarded = 0.03 cfs @ 7.50 hrs, Volume= 0.045 af Primary = 1.80 cfs @ 12.15 hrs, Volume= 0.104 af Routed to Link 7 : Proposed Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 414.08' @ 12.14 hrs Surf.Area= 400 sf Storage= 640 cf Plug-Flow detention time= 14.9 min calculated for 0.149 af (100% of inflow) Center-of-Mass det. time= 14.9 min ( 773.4 - 758.5 ) Volume Invert Avail.Storage Storage Description #1 411.50' 329 cf 10.00'W x 40.00'L x 3.00'H Prismatoid 1,200 cf Overall - 377 cf Embedded = 823 cf x 40.0% Voids #2 412.00' 377 cf 24.0" Round Pipe Storage x 3 Inside #1 L= 40.0' S= 0.0020 '/' 706 cf Total Available Storage Device Routing Invert Outlet Devices #1 Discarded 411.50' 2.900 in/hr Exfiltration over Surface area #2 Primary 412.00' 12.0" Round Culvert L= 14.0' Ke= 0.100 Inlet / Outlet Invert= 412.00' / 411.94' S= 0.0043 '/' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 0.79 sf #3 Device 2 412.00' 6.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads #4 Device 2 414.00' 24.0" x 24.0" Horiz. Grate C= 0.600 Limited to weir flow at low heads Discarded OutFlow Max=0.03 cfs @ 7.50 hrs HW=411.53' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=1.77 cfs @ 12.15 hrs HW=414.07' (Free Discharge) 2=Culvert (Passes 1.77 cfs of 5.52 cfs potential flow) 3=Orifice (Orifice

1=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=1.77 cfs @ 12.15 hrs HW=414.07' (Free Discharge) 2=Culvert (Passes 1.77 cfs of 5.52 cfs potential flow) 3=Orifice (Orifice Controls 1.28 cfs @ 6.50 fps) 4=Grate (Weir Controls 0.49 cfs @ 0.87 fps) 44