V4 11 Stormwater Report Rev 3 1 26 2023

100-yr 10-yr 2-yr Phase 1 Phase 2/3 Step 5: Caculate Peak Flow Rates by Adjusted Curve Number Calculate the time of concentration and use it along with the adjusted curve numbers determined in Step 4 to calculate the peak flow rates of each of the storm events using NRCS methodology. Note that the time of concentration of a green roof must be calculated based on the vegetation condition, roof slope and drainage path. A green roof with dense vegetation and a milder slope may provide a longer time of concentration, which will slow down the discharge of the roof runoff and lower the peak rate of the runoff. The time of concentration must be calculated in accordance with the velocity method described in the NEH, Chapter 15 - Time of Concentration. New Jersey Stormwater Best Management Practices Manual March 2021 Green Infrastructure BMPs, Chapter 9.4: Green Roofs Page 15