Sunday, March 15, 2009

Revised Draft MPCA Multisector Industrial Stormwater Discharge Permit

UPDATE: On July 6, 2009, MPCA is scheduled to release its proposed Multisector Industrial General Stormwater Permit. In July, Caltha LLP will be hosting seminars in several cities across Minnesota to provide information on the proposed permit and rule changes, and steps facilities can take to reduce their impact.

For more information, go to:

MPCA SWPPP Permit - Industrial Stormwater Permit Reissue Seminars


On March 19, 2009, the Minnesota Pollution Control Agency released a revised working draft of its proposed multi-sector industrial stormwater discharge general permit. This permit, once promulgated, will replace the existing industrial stormwater permit, which expired in October of 2002.

The MPCA draft permit is of interest outside of Minnesota because of the numerous unique requirements that MPCA has included. Many of these go well beyond other current State general permits, and even the most recent US EPA general permit (“MSGP-2008”). Unique features of the MPCA permit include special stormwater antidegradation requirements, design and performance requirements for stormwater infiltration, requirements for mercury minimization, and others.

Some of the key updates in the March 19, 2009 draft include:

Pollution Prevention Requirements:
Additional pollution prevention requirements have been included under each sector-specific requirement (discussed below)

Stormwater Monitoring Requirements:
There are no significant changes to the requirements for all dischargers to conduct both visual and chemical (benchmark) monitoring. However, some important changes related to stormwater monitoring are including in Sector Specific Monitoring Requirements (see sector requirements)
[Read about proposed MPCA industrial stormwater monitoring requirements]
[See flowchart summarizing proposed MPCA industrial stormwater monitoring requirements]

Stormwater Antidegradation Requirements:
Certain discharges that are located within one mile of a “special water” must meet additional requirements. The March 19, 2009 contains no significant amendments to stormwater nondegradation (antidegradation) requirements compared to the previous draft.
[Read more about MPCA stormwater nondegradation (antidegradation) requirements]

Stormwater Infiltration Requirements:
The requirements for stormwater infiltration are largely the same as discussed previously. There now is clarification that design standards for infiltration basin must be met for new basins or when upgrading existing basins.
[Read more about draft requirements for stormwater infiltration]

Sector Specific Requirements:
One of the key additions compared to the previous working draft is the addition of sector specific requirements. The general permit will ultimately contain additional requirements for about thirty different industrial sectors. Most sectors now have sector requirements listed in the draft permit.

As examples, click below to review additional requirements for two sectors:

Proposed stormwater requirements for Food and Kindred Products Sector (Sector U)
Proposed stormwater requirements for Steam Electric Generating Facilities (Sector O)

Looking for different sector information? Click here to request information on proposed stormwater requirements for specific sector.

The March 19, 2009 draft for the industrial stormwater discharge general permit is a “work in progress”; it is anticipated that requirements will change prior to being published for public review and comment.

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
Caltha LLP Website

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