TN Multi-Sector General Permit | 2025 Update

The TMSP regulates point source stormwater discharges associated with industrial materials and activities. Industrial material and activities include, but are not limited to: “material handling equipment or activities; industrial machinery; raw materials, intermediate products, by-products, and final products; or waste products.” Material handling activities include: “storage, loading and unloading, transportation or conveyance, of any raw material, intermediate product, by-product, final product or waste product.” Any facility that has industrial activities that are exposed to stormwater need to have a stormwater permit. Within Tennessee, that permit will often be the TMSP. Facilities that do not have any industrial materials or industrial activities exposed to rainfall do not need an NPDES or TMSP permit but instead apply for a “no exposure certification.” In some cases, a facility may need an individual NPDES permit, if that is the case, and you need guidance, please feel free to reach out or fill out the “contact us” form.

Each facility that meets the criteria for the TMSP must send a Notice of Intent (NOI) and facility map to the Department of Environment and Conservation Division of Water Resources. By submitting an NOI, the applicant has:

1. Obtained and read the permit
2. Acknowledges the applicant’s ability to comply with permit terms and conditions

The submitted NOI will include:

1. Facility name and location
2. Description of all industrial activities
3. Names of all receiving waters
4. Facility Map
   1. Boundaries of the property
   2. Location of discharge points (outfalls) with unique ID
   3. Locations of all receiving waters, including wetlands and Municipal Storm Sewer System (MS4)

Once the division has received the NOI, they will provide the applicant with a Notice of Coverage (NOC). The NOC states that the division has received the NOI and has accepted the issuance of the TMSP. Now the facility is permitted under the TMSP, all compliance items within the permit must be followed, or will be liable for enforcement action. If the facility is no longer in operation or has any industrial materials or activities covered in the TMSP, the facility will send the division a Notice of Termination (NOT).

• Generate and implement a Storm Water Pollution Prevention Plan (SWPPP)
• Inspections:
  • Quarterly Visual Assessments: Visual assessments of all outfalls
  • Annual Comprehensive Inspections: Comprehensive facility inspections (all outfalls and entire site) must be conducted once per year.
• Sector Specific Items. The TMSP provides detailed information regarding each sector (Timber Production, Paper Products Manufacturing, Chemical Manufacturing, etc.) that should be reviewed for each facility.

Note: Documentation of the SWPPP, Inspections, and site-specific items is required under the TMSP.

Failure to comply with the permit requirements can result in enforcement action from the division.

Existing Facilities: Facilities already permitted with the previous version of the TMSP will need to submit a new NOI before September 30, 2025 (91 days after the issuance of the updated permit). Additionally, facilities should look to the section below listing the major updates to the TMSP to ensure that compliance with the new permit is complete.

New Facilities: Facilities without TMSP coverage should submit NOI at least 30 calendar days prior to commencing discharge.

New Operators: Facilities with TMSP coverage should submit an NOI at least five days prior to the operator change.

Several requirements for the facility SWPPP have been updated. A full list of the requirements for the SWPPP can be found in Part 3.2 of the updated TMSP.

Note: The Division is “encouraging” facilities to submit the facility-specific SWPPP with their NOI. If SWPPP is submitted electronically, it will be publicly available and may need to be redacted to exclude confidential information. Submitting the SWPPP electronically is optional.

1. Additional Implementation Measure (AIM)

AIM are measures that were implemented in 2021 by the EPA’s multi-sector general permit. Although the TMSP is similar to that of the EPA’s, the TMSP is a simplified version. In short, AIM are incremental and progressively stringent responses to benchmark exceedances in stormwater discharge permits, requiring facilities to take corrective actions when monitoring results exceed established benchmarks.

1.1 Triggering Event:

A Triggering Event is any time an analytical exceedances of the benchmark value or Effluent limitations guidelines (ELG) occurs. After such an event the permittee is required to implement AIM within 30 days of receiving the results. These items include:

• Conduct Comprehensive facility inspection, with a goal to identify source or sources of pollutants of concern
• Determine if SWPPP modifications are necessary
• Initiate SWPPP modifications (if applicable)
• Update SWPPP with findings
• Provide summary of actions in NetDMR

1.2 Repeating Triggering Event:

If repeated triggering events occur for the same parameter at the same outfall, the facility must implement one of the two options:

• Engage a licensed professional to conduct an evaluation of facility and recommend Stormwater Control Measures (SCM) improvements;
• Increase stormwater runoff monitoring frequency to once per quarter. Increased monitoring frequency is limited to:
  • the pollutant(s) which exceeded benchmark values; and
  • the outfall(s) where exceedance was observed.

Note: AIM does include several other items regarding compliance. If you have questions or concerns regarding these items, please contact SEC and we would be happy to advise your specific facility.

2. Discharges to Impaired Waters

The 2025 TMSP does not authorize discharges that would add measurable loading of a pollutant that is causing or contributing to the impairment of a water body, including waters with unavailable parameters. This is applicable to:

• New facilities; and
• Existing discharges proposing an increase of pollutant loading.

In such case, the permittee must obtain an individual NPDES permit. Changes to sector-specific requirements, which may include monitoring, reduced monitoring, or other requirements

3. Changes to Sector-Specific Requirements

Many sector-specific requirements have been updated. This updates may include increased or reduced monitoring. For an in-depth  site-specific review, please reach out to Stevens EHS directly.