2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640\circledR 2025 HydroCAD Software Solutions LLC Page 19
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NJ DEP 2-hr WQ Rainfall=1.24"
| Area (ac) | CN | Description |
|---|---|---|
| 0.090 | 39 | >75% Grass cover, Good, HSG A |
| 0.090 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 4.8 | 58 | 0.0300 0.20 |
| Sheet Flow, A-B | ||
| Grass: Short n= 0.150 P2= 4.04" | ||
| 4.8 | 58 | Total Increased to minimum Tc = 10.0 min |
4.8 58 Total, Increased to minimum Tc = 10.0 min
Subcatchment 19S: Study Area Road Undetained (Perv)
| 2026-02 Existing and Proposed | NJ DEP 2-hr | WQ Rainfall=1.24" |
|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 20 |
| Inflow Area = | 0.740 ac, 97.30% Impervious, Inflow Depth = 1.00" for WQ event | ||
|---|---|---|---|
| Inflow = | 1.33 cfs @ | 1.17 hrs, Volume= | 0.061 af |
| Outflow = | 0.70 cfs @ | 1.43 hrs, Volume= | 0.061 af, Atten= 48%, Lag= 15.3 min |
| Discarded = | 0.70 cfs @ | 1.43 hrs, Volume= | 0.061 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= 117.70' @ 1.43 hrs Surf.Area= 3,001 sf Storage= 580 cf
Plug-Flow detention time=7.8 min calculated for 0.061 af (100% of inflow) Center-of-Mass det. time=7.8 min (87.9 - 80.1)
| Volume | Invert | Avail.Storage | Storage Description |
|---|---|---|---|
| #1A | 117.50' | 0 cf | 31.63'W × 94.88'L × 3.00'H Field A |
| #2A | 117.50' | 8,729 cf | 8,999 cf Overall - 8,999 cf Embedded = 0 cf × 40.0% Voids\nACO StormBrixx SD 1 × 384 Inside #1\nInside= 23.7"W × 36.0"H => 5.75 sf × 3.95'L = 22.7 cf\nOutside= 23.7"W × 36.0"H => 5.93 sf × 3.95'L = 23.4 cf\n384 Chambers in 16 Rows |
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
| Device | Routing | Invert | Outlet Devices |
|---|---|---|---|
| #1 | Primary | 117.50' | 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 |
| #2 | Device 1 | 118.81' | 6.0'' Vert. Orifice C= 0.600 Limited to weir flow at low heads |
| #3 | Discarded | 117.50' | 10.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = -4.00' |
| Discarded OutFlow Max=0.70 cfs @ 1.43 hrs HW=117.70' (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) | |||