Runoff from precipitation that lands on industrial sites
Industrial stormwater is runoff from precipitation (rain, snow, sleet, freezing rain, or hail) that lands on industrial sites (e.g. manufacturing facilities, mines, airports). This runoff is often polluted by materials that are handled or stored on the sites, and the facilities are subject to regulations to control the discharges.
Regulation in the United States.
In the United States, facilities that discharge industrial stormwater to surface waters must obtain a permit under the National Pollutant Discharge Elimination System (NPDES), pursuant to the Clean Water Act. Stormwater permit regulations issued by the United States Environmental Protection Agency (EPA) govern the permit process. EPA published its "Phase I" stormwater rule, which covers industrial dischargers, in 1990.
Most stormwater permits in the U.S. are issued by the agencies in 47 states that have been given authority by EPA. EPA regional offices issue the stormwater permits in the remaining parts of the country.
Multi-sector general permit.
EPA published its "Multi-Sector General Permit" (MSGP) initially in 1995 to govern how industrial stormwater should be managed, and periodically it has updated and reissued the permit. The 2021 MSGP covers 30 industrial and commercial sectors:
The permit is applicable to facilities in Massachusetts, New Hampshire, New Mexico, the District of Columbia and federal insular areas (territories). The other states have developed their own state-specific industrial stormwater permits (e.g. California's Industrial General Permit). State-issued general permits often include the same requirements as EPA's permit, but some states have additional requirements.
Construction site stormwater.
Under EPA regulations, stormwater runoff from construction sites is also classified as industrial stormwater, however these discharges are covered by a separate set of permits. EPA periodically publishes its "Construction General Permit" and the approved state agencies publish similar permits, to regulate discharges from construction sites of 1 acre (4,000 m2) or more. (Also covered are sites that are less than one acre in size, that are part of a larger common plan of development that will disturb more than 1 acre.) In addition to implementing the NPDES requirements, many states and local governments have enacted their own stormwater management laws and ordinances, and some have published stormwater treatment design manuals. Some of these state and local requirements have expanded coverage beyond the federal requirements. For example, the State of Maryland requires erosion and sediment controls on construction sites of 5,000 sq ft (460 m2) or more.
References.
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