Analysis - Proposed Conditions NOAA 24-hr D 10 YR-C Rainfall=5.38"
Prepared by Civil Core Consulting Printed 12/19/2025
HydroCAD® 10.20-8a s/n 13637 © 2025 HydroCAD Software Solutions LLC Page 166
Summary for Pond 2P: Subsurface Infiltration Basin 1
Inflow Area = 73,567 sf, 27.76% Impervious, Inflow Depth = 1.39" for 10 YR-C event
Inflow = 0.56 cfs @ 12.09 hrs, Volume= 8,501 cf
Outflow = 0.56 cfs @ 12.09 hrs, Volume= 8,501 cf, Atten= 0%, Lag= 0.0 min
Discarded = 0.56 cfs @ 12.09 hrs, Volume= 8,501 cf
Primary = 0.00 cfs @ 0.00 hrs, Volume= 0 cf
Routed to Link 32L : POA1
Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs
Peak Elev= 87.01' @ 12.09 hrs Surf.Area= 2,475 sf Storage= 10 cf
Plug-Flow detention time= 0.3 min calculated for 8,500 cf (100% of inflow)
Center-of-Mass det. time= 0.3 min ( 985.5 - 985.2 )
Volume Invert Avail.Storage Storage Description
#2A 87.50' 3,188 cf 14,850 cf Overall - 3,979 cf Embedded = 10,871 cf x 40.0% Voids
Outside= 42.0"W x 42.0"H => 8.86 sf x 20.00'L = 177.2 cf
20 Chambers in 5 Rows
#1A 87.00' 4,349 cf 27.50'W x 90.00'L x 6.00'H Field A
ADS N-12 36" x 20 Inside #1
Inside= 36.1"W x 36.1"H => 7.10 sf x 20.00'L = 142.0 cf
24.50' Header x 7.10 sf x 2 = 347.9 cf Inside
7,536 cf Total Available Storage
Storage Group A created with Chamber Wizard
Device Routing Invert Outlet Devices
#2 Device 1 88.00' 12.0" Round Culvert
#1 Primary 92.59' 48.0" x 48.0" Horiz. Grate C = 0.600
Limited to weir flow at low heads
L= 119.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 88.00' / 86.00' S= 0.0168 /" Cc= 0.900
n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf
#3 Discarded 87.00' 10.000 in/hr Exfiltration over Surface area Phase-In= 0.01'
Discarded OutFlow Max=0.56 cfs @ 12.09 hrs HW=87.01' (Free Discharge)
3=Exfiltration (Exfiltration Controls 0.56 cfs)
Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=87.00' TW=0.00' (Dynamic Tailwater)
1=Grate ( Controls 0.00 cfs)
2=Culvert ( Controls 0.00 cfs)
Pond 2P: Subsurface Infiltration Basin 1