Stormwater Report 1

Time of Concentration Calculations Project #: 24-170 Project: The Estate County: Essex Pre-Development Post-Development Drainage Area: DA-1 (Future Projected) 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 20 80 Flow Length, L (total ≤ 100 ft) Two-Year 24-Hour Rainfall, P2 4.09 4.09 0.025 0.05 Land Slope, s (ft/ft) 3.19 7.32 Tt 4.09 - 10.50 Shallow Concentrated Flow Surface Description Flow Length, L Watercourse Slope, s (ft/ft) Average Velocity Tt Segment 1 Unpaved 70 0.05 3.6 0.33 Segment 2 paved 159 0.05 4.6 0.58 Segment 3 Segment 2 4.909 7.854 0.63 0.035 HDPE Pipe 0.01 20.38 310 0.25 Segment 3 - 0.91 Channel Flow Cross Sectional Flow Area, a Wetted Perimeter, Pw Hydraulic Radius, r Channel Slope, s Manning's Roughness Description Manning's Roughness Velocity Flow Length Tt Segment 1 4.909 7.854 0.63 0.01 HDPE Pipe 0.01 10.89 24 0.04 - - 0.29 11.70