In August, the U.S. Environmental Protection Agency (EPA) updated its Rainfall Erosivity Factor Calculator, which can help you determine the value of the rainfall erosivity factor (R-factor) on a small construction project (disturbing less than five acres). Small construction sites with an R-factor of less than five (5) qualify for a waiver from stormwater permitting requirements in areas where EPA is the permitting authority. Certain state permitting authorities also may accept low erosivity waivers.
To determine whether your small construction site qualifies for the Low Erosivity Waiver (LEW), you can access the Rainfall Erosivity Factor Calculator here. In addition, EPA has a fact sheet available that may help determine applicability, click here. And Appendix C of the 2012 stormwater Construction General Permit (regarding small construction waivers) is available here. If you qualify for a waiver, be sure to submit a waiver certification using the electronic Notice of Intent (eNOI) system.
To qualify for the waiver, your small construction project must be located where EPA is the permitting authority. Click here to see a chart of those areas. If your project is located in a state that is authorized to run EPA’s stormwater construction program, then you will need to contact your state to see whether they accept low erosivity waivers. The Construction Industry Compliance Assistance Center has links to each state’s stormwater program, click here.
According to the EPA website, the agency updated “its Rainfall Erosivity Factor Calculator to correct known problems and to use updated data from the Natural Resources Conservation Service’s (NRCS) Revised Universal Soil Loss Equation, Version 2 (RUSLE2) database.”
For more information, contact Leah Pilconis at pilconisl@agc.org.
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