Industrial stormwater: Permit development and program history

Tentative timeline (subject to change)

  • January – October 2018: Review existing permit language; sampling and other permit requirements. Draft list of suggested changes; compare EPA and Minnesota’s permit language
  • November 2018 – January 2019: Draft changes
  • February 2019: Submit draft to MPCA legal staff for review. Draft fact sheet, “what’s changed?” document
  • March 2019: Prep document for public notice process
  • April-Mid May 2019:  Prep document for Public Notice in State Register
  • May 20, 2019:  State Register Notice is published, Public Comment period begins
  • June 18, 2019: Public Comment period ends
  • June 19-June 30, 2019:  2020 permit language finalized following Public Comment Period, MPCA Commissioner approval
  • July/August 2019:  Timeframe for permittees to update/develop SWPPPs in order to apply for new permit coverage
  • January 1, 2020–March 31, 2020:  Timeframe to apply for new permit coverage
  • October 1, 2019-March 31, 2020:  Permittees continue to follow the 2015-2020 Industrial Stormwater Permit/No Exposure Certification requirements
  • April 1, 2020: New Industrial Stormwater Permit/No Exposure Certification is reissued and in effect until April 1, 2025.

General changes

  • Getting the permit into a “Tempo-ready” format: The formatting and overall look of the new permit will be different in order to fit into MPCA’s new Tempo database system. These visual differences can be seen in MPCA’s Construction Stormwater 2013 general permit and 2018 general permit.
  • Changing language to present tense, plain language: As we reformat the permit, we’re changing the language (not the requirements) to reflect active voice/present tense requirements, and trying to make the requirements easier to understand.
  • Corrected four incorrect permit references for monitoring waiver forms

Part I

  • Authorization of discharges: For transferring coverage, remove “prior owner/operator” requirement; just have current owner and operator sign.
  • Clarity of vehicle washing prohibition: Within the limitations on authorization, add examples: 2. Domestic and industrial wastewater and process wastewater. For example, wash water, commercial equipment and/or vehicle cleaning.

Part III

  • Salt storage, salt management: BMPs for salt management: cover/store indoors, direct drainage away from receiving waters, reduce exposure when adding/removing from pile, and document salt pile location within SWPPP. Hired contractors should minimize use of salt.
  • Infiltration for all sectors: Infiltration for all Industrial Sectors:  Prohibits new infiltration devices in areas of predominately Hydrologic Soil Group D (clay) soils, and areas where soil infiltration rates are more than 8.3 inches per hour.  Changed wording from ‘infiltration device’ to ‘infiltration system.
  • BMP maintenance: Reduce time for installing backup BMPs from 7 days to 48 hours

Part IV

  • SWPPP modifications: If there are changes in personnel responsible in for any permit requirement, update SWPPP. Removed 1:24000 facility map scale requirement.
  • Annual reports: Added a new permit chapter Annual Report. No changes were made to the Annual Report requirements.

Part V

  • pH calibration: The Permittee shall maintain written records of all calibrations and maintenance of their pH meter within SWPPP.

Part VII

  • Remove :
    • “Any additional” references within each sector “chapter”
    • Part 2 in each chapter; language is largely redundant to part 1 in each sector chapter.
  • Sectors J & L: A separate CSW permit is not required for certain activities considered part of overall industrial operations for these facilities.
  • Sector J: Dewatering discharges aren’t allowed, remove phrase “dewatering or other process water”
  • Sectors M and N
    • Sector M: Corrected the permit benchmark values listed for Toluene and Ethyl benzene.  Added BMP options
    • Sector N: Added option of storing recyclables indoors or minimizing exposure
  • Sub-sector S3 definition: Changed to: “non-propeller aircraft departures”
  • Sector S: For airports with no de-icing activities, sample for TSS only.  For all airports, remove pH sampling requirement.

Appendix A

  • Anti-degradation review complete: no additional changes beyond what’s proposed above.

2013 - 2015

  • October 2013: MPCA staff compare USEPA's draft MSGP with Minnesota MSGP
  • November - March 2014: Draft suggested changes into draft permit
  • March 31 - April 30, 2014: 30-day public notice period for the MPCA draft permit
  • May / June 2014: MPCA staff make changes to draft permit in response to public comments
  • Late June 2014: Estimated date the draft permit is approved
  • July 7 - October 5, 2014: Time to re-apply / re-certify for permit coverage / No Exposure
  • April 5, 2015: Permit is re-issued and becomes effective

2015 documents

What changed in the 2015 permit?

Streamlined sampling requirements: 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 who applies after April 5, 2015, will start sampling requirements during the next full calendar quarter.

Requiring four samples before averaging: Permittees will be required to collect a minimum of four samples, during four separate calendar 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 collect four samples; this may be because samples couldn't be collected due to drought/frozen conditions or no off-site discharges. These are considered legitimate "no flow" explanations.

Quarterly sampling until benchmark values: Permittees with exceedances will continue sampling quarterly until four quarters of averaged results are below the benchmark value.

Limitations on infiltration:  Construction of a new infiltration device is prohibited in:

  1. Areas that receive discharges from vehicle fueling and maintenance activity.
  2. Areas with less than three feet of separation distance from the bottom of the infiltration device to the elevation of the seasonally saturated soils to the top of the bedrock.
  3. Areas of predominantly Hydrologic Soil Group D (clay) soils unless allowed by a local unit of government with a current MS4 permit.
  4. Areas where soil infiltration rates are more than 8.3 inches per hour unless soils are amended to slow the infiltration rate below 8.3 inches per hour or as allowed by a local unit of government with a current MS4 permit.

2006 - 2010

The MPCA began work to reissue the expired General Stormwater Permit for Industrial Activity. Key steps along the way included:

November 2006: MPCA created the Stormwater Steering Committee’s Industrial Stormwater Work Group. It was made up of members of the Minnesota Stormwater Steering Committee and public and private organizations. The Work Group’s task was to help the Industrial Stormwater Program draft the new permit.

2010 documents

2002 - 2003


The 1997 General Stormwater Permit for Industrial Activity Permit MN G611000 expired on October 31, 2002. Before the permit expired, the MPCA drafted the Industrial Stormwater Permit and public noticed the draft for comments:

During the public notice comment period, the MPCA received written comments on several issues including requirements for outstanding resource value waters and nondegradation analysis, requirements for completed total maximum daily loads, monitoring, and SWPPPs.

In the interim, to address the time between the expired permit and reissuance of the new General Stormwater Permit for Industrial Activity, previous permit holders were covered by Minn. R. 7001.0160. “Any person who holds an expired permit…and who has submitted a timely application for reissuance of the permit may continue to conduct the permitted activity in accordance with the terms and conditions of the expired permit until the agency takes final action on the application.”

New, non-municipal facilities and newly regulated municipally owned or operated industrial facilities had to submit a permit application in order to meet the federal requirements of applying for NPDES permit coverage for industrial activity. Until the general permit was reissued, facilities had to develop and implement a SWPPP that complied with the Draft NPDES General Stormwater Permit for Industrial Activity which included the SWPPP requirements contained in the expired permit. 


EPA’s Stormwater Phase II regulations became effective on March 10, 2003, and continued to regulate the ten categories of industrial activity:

  1. Facilities subject to stormwater effluent limitation guidelines, new source performance standards, or toxic pollutant effluent standards under 40 CFR Subchapter N
  2. Heavy industrial facilities (SIC codes 24, 26, 28, 29, 311, 32,33,3441, 373
  3. Mineral industry (SIC codes 10, 12, 13, 14)
  4. Hazardous waste treatment, storage or disposal facilities
  5. Landfills, land application sites and open dumps that receive or have received industrial waste
  6. Facilities involved in recycling of material, including metal scrap yards, battery reclaimers, salvage yards, and automobile junk yards, including but limited to those classified as SIC codes 5015 and 5093
  7. Steam electric power generating facilities
  8. Transportation facilities (SIC codes 40, 41, 42 [except 4221-25], 43, 44, 45 and 5171 which have vehicle maintenance shops, equipment cleaning operations, and airport deicing operations
  9. Sewage treatment works
  10. Light industrial facilities (SIC codes 20, 21, 22, 23, 2434, 25, 265, 267, 27, 283, 285, 30, 31, 323, 34, 35, 36, 37, 38, 39, 4221, 4222 and 4225)

The regulations extended the No Exposure exclusion to all industrial stormwater categories and required municipally owned or operated industrial facilities to obtain permit coverage or certify No Exposure.