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Industrial Stormwater Permitting and NPDES Categories

Stormwater runoff from areas where industrial activities and materials are exposed to stormwater can contain toxic pollutants and other contaminants, such as trash, debris, oil, and grease. Development of impervious surface areas can also increase surface runoff rates, volumes, and pollutant loads, which can cause harm to the receiving waters. Authorized by the Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) requires permit coverage for stormwater discharges from the following 11 categories:

(i) Facilities subject to federal stormwater effluent discharge standards in 40 CFR Parts 405-471;
(ii) Heavy manufacturing, including Standard Industrial Classification (SIC) codes 24 (except 2434), 26 (except 265 and 267), 28 (except 283 and 285), 29, 311, 32 (except 323), 33, 3441, and 373;
(iii) Coal and mineral mining and oil and gas exploration and processing, including SIC codes 10-14;
(iv) Hazardous waste treatment, storage or disposal facilities;
(v) Landfills, land application sites, and open dumps with industrial wastes;
(vi) Metal scrapyards, salvage yards, automobile junkyards, and battery reclaimers, including SIC codes 5015 and 5093;
(vii) Steam electric power generating plants including coal-handling sites;
(viii) Transportation facilities that have vehicle maintenance, equipment cleaning, or airport deicing operations, including SIC codes 40, 41, 42 (except 4221-25), 43, 44, 45, and 5171;
(ix) Treatment works treating domestic sewage with a design flow of 1 million gallons per day;
(x) Construction sites that disturb one acre or more (permitted separately, see “Construction Stormwater Permitting” section below); and
(xi) Light Manufacturing, including SIC codes 20-23, 2434, 25, 265, 267, 27, 283, 285, 30, 31 (except 311), 323, 34, 37-39, and 422-25.

The General Permit for Stormwater Discharges Associated with Industrial Activity, also known as the Multi-Sector General Permit (MSGP), covers new and existing point source discharges of stormwater associated with industrial activity. The MSGP provides general requirements that apply to all facilities covered by the permit, as well as sector-specific requirements, based on the facility’s SIC code.

To obtain coverage under the MSGP, facilities must submit a Notice of Intent (NOI). Applicants in states who have not been delegated permitting authority by US EPA can submit applications through US EPA’s Central Data Exchange (CDX). Some delegated states, such as Ohio, also offer web-based permitting systems where NOIs can be submitted electronically.

Stormwater permits are not required for discharges to combined sewer systems, although some facilities located in combined sewer systems may still discharge to surface waters via sheet flow, for example, and would be required to obtain a permit.

GT works closely with clients during the stormwater permit application process, and helps clients achieve and maintain compliance with the MSGP by determining the general and sector-specific requirements that apply to them.

Industries We Serve

Conditional Exclusion for No Exposure

If all industrial materials and activities at a facility are protected by a storm-resistant shelter that prevents exposure to rain, snow, snowmelt, and/or runoff, the facility may qualify for No Exposure Certification, and, if so, would not be required to obtain coverage under the MSGP.

In order to qualify for No Exposure, facilities must submit a No Exposure Certification application, which must be renewed every five years. If changes at a facility will result in industrial activities or materials becoming exposed to stormwater, the facility must submit an NOI to obtain coverage under the MSGP prior to the changes occurring.

GT can evaluate a facility’s activities and storage and make a determination as to whether it qualifies for No Exposure Certification. GT can also recommend practices to facilities to eliminate exposure and qualify for No Exposure, in efforts to reduce the costs and regulatory burden of complying with the MSGP.

Stormwater Pollution Prevention Plans (SWPPPs)

The MSGP requires permittees to prepare and implement a Stormwater Pollution Prevention Plan (SWPPP). SWPPPs are site-specific written plans that identify potential pollutant sources at a facility and describe control measures and best management practices (BMPs) implemented to reduce or eliminate pollutants in stormwater discharges and comply with the terms and conditions in the MSGP. Control measures can include structural controls, such as retention ponds and vegetative swales; as well as non-structural controls, such as good housekeeping, maintenance, and spill prevention and response procedures. Additional non-structural BMPs such as employee training, inspections, and monitoring are also required elements of a SWPPP.

A typical SWPPP identifies a stormwater pollution prevention team, and includes a site description and detailed map, potential pollutant sources, control measures, schedules and procedures, and certification. Records related to training, inspections, monitoring, maintenance, and corrective actions should also be maintained with a facility’s SWPPP. GT has developed SWPPPs for clients in a variety of industrial sectors to ensure compliance with the MSGP. GT can provide cost-effective BMP recommendations, and can assist with implementation of the plan by providing training, sampling, and inspection support.

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Construction Stormwater Permitting

Stormwater discharges from construction activities can cause pollutants such as sediment, oil and grease, chemicals, and debris to be released to surface waters. NPDES stormwater permits are required for construction activities that disturb one or more acres. In some cases, however, activities that disturb less than five acres may be waived from the requirement to obtain a permit. The NPDES Construction General Permit (CGP) is available for eligible construction activities, and offers a simplified process for obtaining authorization.

Dischargers must submit an NOI to obtain coverage under the CGP prior to the commencement of construction activities. NOI submittal lead times vary depending on the state and watershed affected. Some areas also require applicants to submit a Stormwater Pollution Prevention Plan (SWPPP) with their CGP NOI.

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