Stormwater Compliance FAQ : A guide to understanding stormwater pollution and complying with NPDES
Stormwater pollution has been an on-going concern of the Environmental Protection Agency (EPA) for many years. The National Pollutant Discharge Elimination System (NPDES) program was established to help regulate discharges into waters of the United States. However, many companies are still unclear on their responsibilities in this area. We’ve compiled and answered the top frequently asked questions to assist you in understanding your responsibilities and help you get in compliance.
What is stormwater?
Stormwater is water from precipitation that runs over land and other solid surfaces such as paved streets, parking lots, and building rooftops. This water runoff eventually seeps into the ground or drains into storm sewers and ends up in your local creeks, streams, and rivers.
Why do I need to be concerned about stormwater discharges?
Stormwater runoff leaving your facility can carry pollutants off-site and into storm drains, running directly into local creeks, streams, and rivers without any treatment.
Most stormwater discharges are considered point sources and require coverage by a permit under the National Pollutant Discharge Elimination System (NPDES).
What is NPDES?
The National Pollutant Discharge Elimination System (NPDES) is a permit program designed to control water pollution by regulating point sources that discharge pollutants into waters in the United States.
Who needs a permit?
The NPDES program is organized according to three potential sources: municipal separate storm sewer systems (MS4s), construction activities, and industrial activities.
What permit do I need?
Municipal Separate Storm Sewer Systems (MS4s)
Polluted stormwater is carried through Municipal Separate Storm Sewer Systems, from which it is often discharged untreated into local bodies of water. If you’re an operator of a large, medium, or regulated small MS4 you need to obtain a NPDES permit.
- If you’re an MS4 in a medium or large city/county with a population of 100,000 or more, file for a “Phase I” Individual Permit.
- If you’re a regulated small MS4 in an urbanized area or a small MS4 outside an urbanized area designated by the permitting authority, file for a “Phase II” General Permit.
Every regulated MS4 is also required to develop and implement a stormwater management program (SWMP) to reduce contamination of stormwater runoff and prohibit illegal discharges.
Construction Activities
Stormwater runoff from construction sites can carry pollutants such as sediment, debris, and chemicals into storm sewer systems or local bodies of water. If you’re the operator of a construction site engaged in clearing, grading, or excavating activities disturbing more than one acre, file a Notice of Intent (NOI) under the NPDES General Permit.
Regulated construction activities disturbing more than one acre are also required to develop and implement a construction site erosion control and stormwater management plan. Most construction activities are eligible for coverage under state-issued general permits.
Industrial Activities
Activities that transpire at industrial facilities, such as storage and material handling, can pollute stormwater discharges and transport contaminates to local storm sewer systems and local bodies of water. If you are an industrial or other facility that can possibly discharge any type of pollutant into surface waters, you must obtain an NPDES permit.
- If your stormwater discharge is not contaminated by industrial activity, file for a “No Exposure Certification.”
- If your stormwater discharge contains potential pollutants, file a Notice of Intent (NOI) under the NPDES General Permit.
- If your stormwater discharge contains toxic or hazardous material, or if specified in PM-WM0024a rev.1/2004, file an Individual Permit.
Every regulated industrial facility is also required to develop and implement a Stormwater Written Pollution Prevention Plan (SWPPP) to identify best practices management to control stormwater discharges.
Source: Environmental Protection Agency