Sunday, November 7, 2010

MPCA Storm Water Benchmarks, Comparison To Historic Sector Monitoring Data

In 2010, the Minnesota Pollution Control Agency (MPCA) reissued the Multi-Sector General Permit (MSGP) for industrial stormwater discharges. The reissued permit included significant changes to stormwater discharge requirements for permitted sites, which are now divided into 29 industrial sectors. One of the most significant changes was the requirement for sampling stormwater and reporting results to MPCA. Each sector has been assigned sector-specific stormwater benchmark concentrations. Beginning in June 2011, all sites permitted under the MSGP will have to collect stormwater samples and have samples analyzed for their sector-specific benchmark parameters. If one or more benchmarks are exceeded, sites will be required to upgrade their pollution prevention measures and will need to do further stormwater monitoring.

Since the 1980s, the U.S. Environmental Protection Agency (USEPA) has collected industry-sector data on stormwater discharge. The linked presentation provides a comparison of these historic industrial stormwater results to the current MPCA stormwater benchmark concentrations. The results are discussed in context of which stormwater benchmark parameters have a higher potential for exceedance of benchmark values. This presentation also discusses which of the industrial sectors have a higher potential for exceedance of their specific benchmark values.

Note: Because many States use the same benchmark concentrations used by Minnesota, this analysis and conclusions can be applied to most States.
Link to presentation slides:

Industrial Stormwater Benchmarks – Comparison of New Minnesota Benchmark Concentrations To Historic Industry-specific Testing Results
Caltha LLP provides expert consulting services to public and private sector clients nationwide to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.

For further information contact Caltha LLP at or Caltha LLP Website

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