POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 65
Summary for Pond 8P: SSIB #2 UNDERGROUND
[82] Warning: Early inflow requires earlier time span
Inflow Area = 0.460 ac, 58.70% Impervious, Inflow Depth > 3.64" for 25 year event Inflow = 1.84 cfs @ 12.08 hrs, Volume= 0.139 af Outflow = 0.22 cfs @ 12.88 hrs, Volume= 0.108 af, Atten= 88%, Lag= 47.6 min Discarded = 0.11 cfs @ 12.88 hrs, Volume= 0.096 af Primary = 0.12 cfs @ 12.88 hrs, Volume= 0.012 af Routed to Reach 10 : COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 109.14' @ 12.88 hrs Surf.Area= 0.064 ac Storage= 0.059 af Plug-Flow detention time= 151.0 min calculated for 0.108 af (77% of inflow) Center-of-Mass det. time= 86.4 min ( 828.2 - 741.8 )
VolumeInvertAvail.StorageStorage Description
#1A107.50'0.048 af41.95"W x 66.33"L x 3.00"H Field A
0.192 af Overall - 0.072 af Embedded = 0.120 af x 40.0% Voids
#2A107.83'0.057 afADS N-12 24" x 36 Inside #1 Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00"L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00"L = 78.4 cf 36 Chambers in 12 Rows 40.28' Header x 3.10 sf x 2 = 249.8 cf Inside
0.105 afTotal Available Storage
0.105 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded107.50'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 105.00'
#2Primary109.00'8.0" W × 4.0" H Vert. Orifice/Grate C= 0.600\nLimited to weir flow at low heads
Discarded OutFlow Max=0.11 cfs @ 12.88 hrs HW=109.14' (Free Discharge) 1=Exfiltration (Controls 0.11 cfs)
Primary OutFlow Max=0.12 cfs @ 12.88 hrs HW=109.14' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.12 cfs @ 1.21 fps)