2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04" Prepared by Dynamic Engineering Printed 2/10/2026 HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 41
Summary for Pond 21P: Basin A Routing (StormBrixx)
Inflow Area = 0.740 ac, 97.30% Impervious, Inflow Depth = 3.70" for 2-Year-Projected event
Inflow = 1.81 cfs @ 12.19 hrs, Volume= 0.228 af
Outflow = 0.70 cfs @ 12.63 hrs, Volume= 0.228 af, Atten= 62%, Lag= 26.5 min
Discarded = 0.70 cfs @ 12.63 hrs, Volume= 0.228 af
Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routed to Link 14L : Study Area West (Total)
Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
Peak Elev= 117.98' @ 12.63 hrs Surf.Area= 3,001 sf Storage= 1,394 cf
Plug-Flow detention time= 10.0 min calculated for 0.228 af (100% of inflow) Center-of-Mass det. time= 10.0 min (773.3 - 763.3)
VolumeInvertAvail.StorageStorage Description
#1A117.50'0 cf31.63'W x 94.88'L x 3.00'H Field A
#2A117.50'8,729 cf8,999 cf Overall - 8,999 cf Embedded = 0 cf x 40.0% Voids ACO StormBrixx SD 1 x 384 Inside #1 Inside = 23.7"W x 36.0"H => 5.75 sf x 3.95'L = 22.7 cf Outside = 23.7"W x 36.0"H => 5.93 sf x 3.95'L = 23.4 cf 384 Chambers in 16 Rows
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Primary117.50'15.0" Round Culvert L= 22.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 117.50'/ 117.40' S= 0.0045'/' Cc= 0.900 n= 0.013, Flow Area= 1.23 sf
#2Device 1118.81'6.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads
#3Discarded117.50'10.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = -4.00'
Discarded OutFlow Max=0.70 cfs @ 12.63 hrs HW=117.98' (Free Discharge) —3=Exfiltration ( Controls 0.70 cfs)
Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=117.50' (Free Discharge) —1=Culvert ( Controls 0.00 cfs) —2=Orifice ( Controls 0.00 cfs)
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04" Prepared by Dynamic Engineering Printed 2/10/2026 HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 42
Pond 21P: Basin A Routing (StormBrixx) - Chamber Wizard Field A
Chamber Model = ACO StormBrixx SD 1 (ACO StormBrixx SD) Inside = 23.7" W × 36.0" H => 5.75 sf × 3.95' L = 22.7 cf Outside = 23.7" W × 36.0" H => 5.93 sf × 3.95' L = 23.4 cf 24 Chambers/Row × 3.95' Long = 94.88' Row Length 16 Rows × 23.7" Wide = 31.63' Base Width 36.0" Chamber Height = 3.00' Field Height 384 Chambers × 22.7 cf = 8,728.7 cf Chamber Storage 384 Chambers × 23.4 cf = 8,998.6 cf Displacement Chamber Storage = 8,728.7 cf = 0.200 af Overall Storage Efficiency = 97.0% Overall System Size = 94.88' × 31.63' × 3.00' 384 Chambers 333.3 cy Field
☐ ☐ ☐ ☐