Analysis - Failure NOAA 24-hr D 2 YR-C Rainfall=3.42" Prepared by Civil Core Consulting Printed 12/19/2025 HydroCAD® 10.20-8a s/n 13637 © 2025 HydroCAD Software Solutions LLC Page 55
Summary for Pond 4P: PERVIOUS PAVEMENT 3B
Inflow Area = 8,712 sf,100.00% Impervious, Inflow Depth = 3.19" for 2 YR-C event
Inflow = 0.59 cfs @ 12.12 hrs, Volume= 2,314 cf
Outflow = 0.15 cfs @ 12.46 hrs, Volume= 2,310 cf, Atten= 75%, Lag= 20.1 min
Primary = 0.15 cfs @ 12.46 hrs, Volume= 2,310 cf
Routed to Pond 8P : INFILTRATION BASIN 3
Routed to Pond 8P : INFILTRATION BASIN 3
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3 Peak Elevation = 94.71' @ 12.46 hrs Surf.Area = 5,926 sf Storage = 773 cf Plug-Flow detention time = 106.5 min calculated for 2,310 cf (100% of inflow) Center-of-Mass det. time = 105.4 min (863.3 - 757.9)
VolumeInvertAvail.StorageStorage Description
#193.80'593 cfStone Storage Bed (Prismatic)Listed below (Recalc) 1,482 cf Overall × 40.0% Voids
#294.30'222 cfSurface and Base Course (Prismatic)Listed below (Recalc) 1,482 cf Overall × 15.0% Voids
#394.80'1,482 cfSurface (Prismatic)Listed below (Recalc)
2,296 cfTotal Available Storage
Elevation (feet)Surf.Area (sq-ft)Inc.Store (cubic-feet)Cum.Store (cubic-feet)
93.802,96300
94.302,9631,4821,482
Elevation (feet)Surf.Area (sq-ft)Inc.Store (cubic-feet)Cum.Store (cubic-feet)
94.302,96300
94.802,9631,4821,482
Elevation (feet)Surf.Area (sq-ft)Inc.Store (cubic-feet)Cum.Store (cubic-feet)
94.802,96300
95.302,9631,4821,482
DeviceRoutingInvertOutlet Devices
#1Device 393.80'2.5" Vert. Orifice C = 0.600
#2Device 394.80'48.0" x 48.0" Horiz. Grate C = 0.600
#3Primary92.00'12.0" Round Culvert L = 52.0' RCP, groove end projecting, Ke = 0.200Inlet / Outlet Invert= $ 92.00'/90.75' $ S = 0.0240'/ Cc = 0.900n=0.011, Flow Area=0.79 sf
Primary OutFlow Max=0.15 cfs @ 12.46 hrs HW=94.71' TW=93.27' (Dynamic Tailwater) 3=Culvert (Passes 0.15 cfs of 4.90 cfs potential flow) 1=Orifice (Orifice Controls 0.15 cfs @ 4.31 fps) 2=Grate (Controls 0.00 cfs)