Changes to MPCA Benchmark Monitoring Requirements For Permitted Industries

Written By: Caltha LLP | Published On: 16th August 2014 | Category: Stormwater, Water | RSS Feed

The revised MPCA general industrial stormwater discharge permit has been finalized and will be effective on April 5, 2015. The new permit makes some changes to the compliance monitoring requirements that permitted facilities will need to address:

  1. All existing Permittees who apply between July 7, 2014 and October 5, 2014 would conduct a year of quarterly sampling starting July 1, 2015. Any Permittee that applies after April 5, 2015 will start sampling requirements the next full calendar quarter after the application is submitted.
  2. MPCA now requires four samples before averaging. Facilities will be required to collect a minimum of four samples, collected over four separate quarters, before averages can be calculated and compared with the Permit’s benchmark value(s). It is acceptable if it takes more than four quarters to get four samples because samples couldn’t be collected due to drought/frozen conditions or no offsite discharges (legitimate “no flow” explanations).
  3. Starting in April 2015, Permittees with exceedances will  be required to continue sampling quarterly until four quarters of averaged results are below the benchmark value

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