Storm Exemption

{
  "id": "MLC-T-ENV-026880",
  "term": "Storm Exemption",
  "field": "Environment",
  "definition": "Applies to this subpart M only. If, as a result of precipitation (rainfall or snowmelt), a source subject to this subpart has an overflow or discharge of effluent which does not meet the limitations or standards of this subpart, the source may qualify for an exemption from such limitations and standards with respect to such discharge if the following conditions are met:(1) The treatment system is designed, constructed, and maintained to contain the maximum volume of untreated process wastewater which would be discharged, stored, contained and used or recycled by the beneficiation process into the treatment system during a 4-hour operating period without an increase in volume from precipitation or infiltration, plus the maximum volume of water runoff resulting from a 5-year, 6-hour precipitation event. In computing the maximum volume of water which would result from a 5-year, 6-hour precipitation event, the operator must include the volume which would result from the plant site contributing runoff to the individual treatment facility.(2) The operator takes all reasonable steps to maintain treatment of the wastewater and minimize the amount of overflow.(3) The source is in compliance with the BMP in § 140.148 and related provisions of its NPDES permit.(4) The operator complies with the notification requirements of § 122.41 (m) and (n) of this title. The storm exemption is designed to provide an affirmative defense to an enforcement action. Therefore, the operator has the burden of demonstrating to the appropriate authority that the above conditions have been met.",
  "references": [
    "40 CFR 440.141 (CFR 2017)"
  ],
  "url": "https://mlchart.com/terminology/environment/storm-exemption/"
}