21 Stormwater Mgmt Report_082025

Date: Project: Project No: 30 Independence Boulevard, Warren, NJ 07059 (908) 668-8300 7/31/2025 West Orange NJA230139.00 Calculated By: CRA Checked By: TXL Requirement: The capacity of the underdrains must be sufficient to allow the systems to drain within 72 hours. Note: Below drain time calculations ensure underdrain size is sized to allow the system to drain within 72 hours and does not take into consideration outlet control structure. Calculations for drain time considering outlet control section provided in Basin Drain Time calculations in the Appendix of this report. Water Quality Pervious Pavement Drain Time: (Drain Time = Water Quality Design Storm Volume / Underdrain Flow Rate) 1,014 Water Quality Volume (CF) Calculated Drain Time = 1,014 CF / 0.33 CFS * (1 hr / 60 min) * (1 min / 60 sec) = 0.9 hours < 72 hours 100-Year Storm Event Pervious Pavement Drain Time: (100-Yr Design Storm Runoff Volume / Underdrain Flow Rate) 11,054 100-Year Volume (CF) Calculated Drain Time = 11,054 CF / 0.33 CFS * (1 hr / 60 min) * (1 min / 60 sec) = 9.4 hours < 72 hours Manning's Equation Design Parameters: Pipe Diameter, D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pipe Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Slope, s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flow Depth, y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Calculations: Cross-Sectional Area, A = D 2 /8 [ θ -sin( θ )] = . . . . . . . . . . . . . . . . . . . . . . . Manning's Coefficient, n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hydraulic Radius, R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Angle, θ = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wetted Perimeter, P = θD /2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flow Depth, y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flow Top Width, T = 2[y( D -y)] 1/2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

w Depth, y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flow Top Width, T = 2[y( D -y)] 1/2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gravity Constant, g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Froude Number, F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 in PVC 0.20 % FULL 0.20 ft2 0.010 0.13 ft 6.28 radians 1.57 ft 0.50 ft 0.00 ft 32.174 ft/s2 0.00 Subcritical Flow • Flow & Velocity: Flow, Q o = 1.486 · R 2/3s 1/2A . . . . . . . . . . . . . . . . . . . . . . . . n 0.33 cfs 0.21 MGD Velocity, V = Q/A . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 1.66 fps 1