What is a SWPPP?
A Stormwater Pollution Prevention Plan (SWPPP) is a site-specific, written document developed to identify potential sources of stormwater pollution at a construction site. The SWPPP will outline the Best Management Practices (BMPs) employed to reduce pollutants in stormwater discharges from the site.
While this article provides a summary for quick reference, comprehensive details describing the SWPPP development and maintenance process can be found in official EPA guidelines which provide detailed instructional guidance.
Who Needs a SWPPP?
A SWPPP is required for sites and facilities seeking to obtain a National Pollutant Discharge Elimination System (NPDES) Permit. The Clean Water Act of 1972 prohibits the discharging of pollutants into any navigable waterways unless an NPDES permit is granted.
The NPDES permit places strict limitations on what pollutants can be discharged, how those discharges are monitored and reported, and other provisions to ensure that the discharges do not impact water quality.
Why is a SWPPP Essential?
Lawsuits brought by EPA and the state department of environmental quality officials can bankrupt unsuspecting companies. Even developers with the best of intentions can run afoul of EPA regulators.
Take a look at what happened in April 2020 when a company putting in a solar array project failed to establish a SWPPP. The resulting lawsuit could be as damaging to the company as the stormwater runoff was to the area surrounding the Massachusetts job site.
Or how about the case of a California company compelled to pay $3.7 million for violating clean water regulations? That company even had a SWPPP in place, but the plan was deemed in violation of the Clean Water Act, resulting in a crushing fine—said to be one of the highest in California history.
No one wants to face this kind of lawsuit and the bad publicity that is sure to follow. And you don’t have to if you put a proper SWPPP in place.
What Should a SWPPP Include?
Having a thorough plan offers you financial protection, while it also safeguards groundwater and neighboring properties. The SWPPP is used to identify all potential pollution sources that could come into contact with stormwater leaving a site, and should include the following elements:
- Site map and description
- Descriptions of activities that could cause pollution
- Best Management Practices & control measures for preventing pollution
- Procedures for conducting inspections and monitoring
- Plans for keeping your SWPPP up to date
Here are some specifics to help guide you in assembling your SWPPP:
Site Map & Description
A site map must be developed and must contain, at a minimum, the following information:
- Drainage patterns
- Approximate slopes after major grading activities
- Areas of soil disturbance
- Outlines indicating all areas that are not to be disturbed
- Locations of all major structural and non-structural controls
- The locations of expected stabilization activities
- Wetlands and surface waters present on the site
- Locations where stormwater may discharge to surface water or municipal separate storm sewer system (MS4)
The site description should describe the nature of construction and major soil-disturbing activities, the size of the areas being impacted, the estimated size and precise location of each discharge point, and the identity of the receiving water or MS4 for each discharge point.
Best Management Practices (BMPs)
The SWPPP should include a detailed description, with timelines, of all controls, applicable BMPs, and mitigation measures that will be implemented at the construction site for each construction phase identified as major soil disturbing activities.
The BMPs within the SWPPP should include, at a minimum:
- All temporary or permanent stabilization practices such as seeding, mulching, application of geotextiles, sodding, etc.
- All structural controls to be implemented to divert stormwater flows from exposed soils and structural practices put in place to store flows, retain sediment on-site, or in any other way limit stormwater runoff. These controls include silt fences, earth dikes, diversions, swales, sediment traps, check dams, subsurface drains, pipe slope drains, level spreaders, storm drain inlet protection, rock outlet protection, reinforced soil retaining systems, gabions, coagulating agents, and temporary or permanent sediment basins.
- All permanent stormwater management controls such as, but not limited to, detention or retention systems, or vegetated swales that will be installed during the construction process.
The SWPPP should also describe, in detail, controls for potential pollutants including, but not limited to:
- Disposal processes for construction debris, chemicals, litter, and sanitary wastes
- Offsite vehicle tracking from construction site entrances/exits
- The proper application rates of all fertilizers, herbicides, and pesticides used at the construction site
- The storage, application, generation, and migration of all toxic substances
Maintenance & Inspections
Every SWPPP should include a detailed maintenance plan for all structural and non-structural controls that are put in place, to assure that they remain effective. Inspection procedures should also be clearly outlined, to include the frequency and timelines of those inspections. Some states and/or municipalities require inspections to be conducted at specific intervals, particularly after rainfall, snow, or storm events.
SWPPPs should clearly identify, for each item included within the plan, the contractor(s) or subcontractor(s) that will implement each specified measure. These contractors are also typically required to sign a certification stating that they will comply with the terms and conditions outlined in the applicable state laws and the SWPPP itself.
Keeping your SWPPP Current
When operations or other site-based changes are made that affect the SWPPP, it should be updated. The California company mentioned earlier in this article was cited in part because it needed to revise its SWPPP. So in addition to the record-setting fine, the firm was also ordered to update its SWPPP and put anti-pollution measures in place.
Some examples of changes that can trigger the need to revise a SWPPP include:
- The introduction of new chemicals or processes
- The removal of processes, tanks, or chemicals
- Moving an operation or storage indoors or outdoors
- Changes in personnel who have an active role in the plan
Even if none of these changes occur, the SWPPP should still be reviewed and adjusted as needed each time the NPDES permit comes up for renewal. Staying on the right side of the law can help keep your organization from getting soaked by regulators.