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 70
Summary for Pond 9P: SSIB #3 UNDERGROUND
[82] Warning: Early inflow requires earlier time span
Inflow Area = 0.460 ac, 100.00% Impervious, Inflow Depth > 5.82" for 25 year event Inflow = 2.92 cfs @ 12.10 hrs, Volume= 0.223 af Outflow = 0.21 cfs @ 13.40 hrs, Volume= 0.146 af, Atten= 93%, Lag= 78.6 min Discarded = 0.15 cfs @ 13.40 hrs, Volume= 0.141 af Primary = 0.05 cfs @ 13.40 hrs, Volume= 0.004 af Routed to Reach 10 : COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 113.06' @ 13.40 hrs Surf.Area= 0.085 ac Storage= 0.114 af Plug-Flow detention time= 171.6 min calculated for 0.145 af (65% of inflow) Center-of-Mass det. time= 94.1 min ( 827.4 - 733.4 )
VolumeInvertAvail.StorageStorage Description
#1A110.80'0.063 af55.75'W x 66.33'L x 3.00'H Field A
0.255 af Overall - 0.096 af Embedded = 0.159 af x 40.0% Voids
#2A111.13'0.076 afADS N-12 24" x 48 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 48 Chambers in 16 Rows 54.08' Header x 3.10 sf x 2 = 335.3 cf Inside
0.139 afTotal Available Storage
0.139 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded110.80'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 108.00'
#2Primary113.00'12.0" W x 6.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlow Max=0.15 cfs @ 13.40 hrs HW=113.06' (Free Discharge) 1=Exfiltration (Controls 0.15 cfs)
Primary OutFlow Max=0.05 cfs @ 13.40 hrs HW=113.06' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.05 cfs @ 0.81 fps)