Tuesday, February 23, 2010

Industrial Stormwater Monitoring in Minnesota - Benchmark Monitoring

The Minnesota Pollution Control Agency has released its revised general permit for stormwater discharges from industrial sites. The most important change in the draft permit compared to the previous MPCA general permit is the requirement to sample stormwater discharges.

Flowchart of MPCA Stormwater Monitoring Requirements

All permittees, regardless of size or business sector, will collect and analyze at least four quarterly samples during Year 2 of permit coverage. These samples will be compared to “benchmark” concentrations. Depending on the results, further quarterly samples may need to be collected in Year 4 and 5, and corrective actions may be required. Additional reporting, including a “Benchmark Exceedence Report” and evaluations will be required for dischargers who continue to exceed benchmark concentrations. All sample results will be reported to MPCA.

Related Links:

Further information on stormwater benchmarks

Further information on selecting stormwater monitoring techniques

Comparison of stormwater benchmarks to historic industrial sector discharge data

It should be noted that some permittees will also be subject to EFFLUENT LIMITS and will have to conduct effluent limit monitoring. The schedule and requirements for effluent limit monitoring are different from Benchmark Monitoring.

Caltha LLP provides expert consulting services to public and private sector clients in Minnesota to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.

For further information contact Caltha LLP at
Caltha LLP Website

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