2025 12 19 Stormwater Report Rev 1

Time of Concentration Calculations Project #: 24-170 Pre-Development Project: The Estate Post-Development County: Essex Drainage Area: DA-1 Sheet Flow Segment 1 Segment 2 Segment 3 Surface Description (Table 3-1) Grass, Dense Grasses Grass, Dense Grasses Manning's Roughness Coeff., n (Table 3-1) 0.24 0.24 - Flow Length, L (total ≤ 100 ft) 20 80 Two-Year 24-Hour Rainfall, P2 (CA) 3.47 3.47 3.47 Two-Year 24-Hour Rainfall, P2 (FP) 4.09 4.09 4.09 Land Slope, s (ft/ft) 0.025 0.05 Tt (CA) 3.5 7.9 - 11.4 Tt (FP) 3.2 7.3 - 10.5 Shallow Concentrated Flow Segment 1 Segment 2 Segment 3 Surface Description Unpaved paved Flow Length, L 70 159 Watercourse Slope, s (ft/ft) 0.05 0.05 Average Velocity 3.6 4.6 - Tt 0.3 0.6 - 0.9 Channel Flow Segment 1 Segment 2 Segment 3 Cross Sectional Flow Area, a 4.909 4.909 7.069 Wetted Perimeter, Pw 7.854 7.854 9.425 Hydraulic Radius, r 0.63 0.63 0.75 Channel Slope, s (ft/ft) 0.04 0.04 0.02 Manning's Roughness Description HDPE Pipe HDPE Pipe HDPE Pipe Manning's Roughness

0.04 0.04 0.02 Manning's Roughness Description HDPE Pipe HDPE Pipe HDPE Pipe Manning's Roughness 0.01 0.01 0.012 Velocity 21.78 21.78 14.50 Flow Length 24 158 155 Tt 0.02 0.12 0.2 0.3 Current Adjusted (CA) 12.6 Future Projected (FP) 11.7