What is involved with determining a sites potential for rainfall erosion?
The second exemption uses the Rainfall Erosivity (R) Factor to determine whether the potential for discharge is low enough to justify a waiver from the requirements. The R-Factor is one of six variables used by the Revised Universal Soil Loss Equation (RUSLE) to predict soil loss from construction sites. (RUSLE was originally used to measure soil loss from agricultural lands at various times of the year on a regional basis.) The Rainfall Erosivity Factor waiver is time-sensitive and is dependent on when during the year a construction activity takes place, how long it lasts, and the expected rainfall and intensity during that time.
