Stormwater runoff is water from rain or snowmelt that does not immediately penetrate soil, but instead enters a drainage system or is otherwise conveyed to a body of water. When stormwater picks up chemicals, particulates or any other form of pollution, these contaminants often impair water quality and make it unfit for drinking, fishing, swimming and other activities.
One way that the Environmental Protection Agency (EPA) helps preserve water quality is to regulate facilities that discharge water containing pollutants from a point source (pipe, drainage ditch, etc.) by requiring them to create a Stormwater Pollution Prevention Plan (SWPPP) and obtain a National Pollutant Discharge Elimination System (NPDES) Permit.
Discharged pollutants that enter a municipal sanitary sewer system are not required to have a NPDES permit, but facilities in this situation should check with the municipality about other permitting requirements.
Common Causes of Water Pollution
Outdoor industrial activities — such as the transfer, storage and handling of materials, salt pile storage or vehicle fueling and maintenance — can result in pollutants being washed away with stormwater. Accidental leaks and spills and improper waste disposal are also common contributors to stormwater pollution.
The EPA has identified six common types of activities at industrial facilities that can cause pollution:
- Loading and unloading operations: Leaks, drips and spills during product transfers are common. If left unchecked, however, this escaped liquid can wash away with stormwater and cause pollution.
- Outdoor storage: Raw materials and finished goods stored outdoors without covers can contribute to stormwater pollution if oil, solid materials or other pollutants are washed off by rain or snow.
- Outdoor process activities: Activities such as mixing concrete, processing timber and crushing rock can discharge pollutants when equipment leaks or leftover particulates enter the water system.
- Dust- or particulate-generating processes: Dust-generating processes such as cement manufacturing, mining and refractories can contribute to water pollution.
- Illicit connections and non-stormwater discharges: Discharging process wastes into stormwater collection systems instead of sanitary sewers is usually prohibited.
- Waste management: Waste management processes such as uncovered waste piles, trash accumulation and landfilling need to be properly controlled to prevent discharges.
What’s in a SWPPP?
A SWPPP is a site-specific, written document signed by a company executive that identifies activities and conditions that could pollute stormwater and details the steps that the company will take to prevent water pollution. It is intended to be a “living document” that is reviewed periodically and updated when facility activities or processes change.
Templates are available at the EPA’s website and can be customized to meet state-specific requirements. For facilities that have Spill Prevention Control and Countermeasure (SPCC) or other plans, these plans can be referenced for applicable SWPPP requirements, but copies of relevant sections should be kept with the SWPPP.
All SWPPPs must include:
- A site description (general location maps, site maps, etc.)
- Descriptions of activities that could cause pollution
- Control measures for preventing spills and minimizing hazards
- Spill response plans
- Procedures for conducting inspections and monitoring
- A process for training employees
- Details of the site’s stormwater pollution prevention team, including names or titles of all members
The EPA also has a number of guidance documents to assist facility planners in developing SWPPPs, but it reminds planners to check for any state-specific requirements that can vary from the federal guidelines.
Who Needs a NPDES Permit?
In most cases, a SWPPP should be prepared – at least in draft form – before obtaining a NPDES permit. Many industrial activities are subject to NPDES permitting, including:
- Facilities subject to effluent discharge standards
- Heavy manufacturing facilities
- Coal and mineral mining
- Oil and gas exploration and processing
- Hazardous waste treatment storage and disposal facilities (TSDFs)
- Landfills and industrial waste dumps
- Metal scrap yards, salvage yards, auto junkyards and battery reclaimers
- Steam electric power generating plants
- Transportation facilities that maintain vehicles or clean equipment
- Airport deicing operations
- Domestic sewage treatment works processing more than 1 million gallons a day
- Light manufacturing
Most industrial activities and discharges are covered under general permits, which help states manage common activities more efficiently. However, some states will issue individual permits for facilities with more unique discharges or for certain industry types.
Properly managing processes and having plans in place to eliminate or mitigate damage caused by leaks and spills helps keep facilities in compliance with regulations while preserving our water resources.