Analysis - Proposed Conditions NOAA 24-hr D 2 YR-F Rainfall=4.04" Prepared by Civil Core Consulting Printed 12/19/2025 HydroCAD® 10.20-8a s/n 13637 © 2025 HydroCAD Software Solutions LLC Page 95

Summary for Pond 2P: Subsurface Infiltration Basin 1

Inflow Area = 73,567 sf, 27.76% Impervious, Inflow Depth = 0.85" for 2 YR-F event

Inflow = 0.42 cfs @ 12.09 hrs, Volume= 5,192 cf

Outflow = 0.42 cfs @ 12.09 hrs, Volume= 5,192 cf, Atten= 0%, Lag= 0.2 min

Discarded = 0.42 cfs @ 12.09 hrs, Volume= 5,192 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= 7 cf

Plug-Flow detention time= 0.3 min calculated for 5,192 cf (100% of inflow)

Center-of-Mass det. time= 0.3 min ( 952.0 - 951.7 )

Volume Invert Avail.Storage Storage Description

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

#1A 87.00' 4,349 cf 27.50'W x 90.00'L x 6.00'H Field A

#2A 87.50' 3,188 cf 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

20 Chambers in 5 Rows

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=0.42 cfs @ 12.09 hrs HW=87.01' (Free Discharge)

3=Exfiltration (Exfiltration Controls 0.42 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