Industrial Stormwater Management
According to the National Water Quality Inventory, runoff from rain, snow-melt, surface drainage, and other types of drainage is a leading source of water pollution. Stormwater at industrial facilities may come into contact with harmful pollutants including toxic metals, oil, grease, de-icing salts, and other chemicals from rooftops, roads, and parking lots, and from activities such as storage, material handling, and grounds management. Common pollutants such as sand, soil, and fertilizers contribute to algal growth, soil-filled lakes, seasonally closed beaches, and other types of water impairments from these pollutants.
Stormwater potentially containing pollutants is associated with 10 categories of industrial activities that are regulated by federal and state requirements. There are a handful of operations on the Twin Cities and Duluth campuses that fall into these regulated categories:
- Recycling facilities
- Fleet with maintenance operations
- Power generation facilities
- Printing and publishing
- Hazardous waste facilities
Industrial stormwater permits are tailored by sector to target specific pollutants and practices that may contribute to the cross-contamination of stormwater. Unless it can be shown there is ?no exposure? of stormwater to an industrial activity, these activities require permit coverage.
Operations covered by the industrial stormwater program are excluded from the scope of municipal permitting to avoid double-regulation.
Controlling Pollutants from Industrial Stormwater
The primary means of controlling cross-contamination of stormwater from industrial activities and to protect downstream water is to implement control measures. To ensure control measures are effective, the permit utilizes the concept of a behavior-driven continuous feedback loop.
Initially, the facility must determine what activities and materials are managed on-site and strategies that the facility is using to meet the permit-required control measures. This assessment is written in the permit-required Stormwater Pollution Prevention Plan (SWPPP).
Activities and Significant Materials
The SWPPP identifies the types of activities performed at the facility, including where waste materials are stored, where and how chemicals and fuels are loaded-in or moved around the facility, and which parts of a process or maintenance are performed outside ? and which pollutants are associated with the activity of material.
Pollutants potentially in contact with stormwater come from:
- Vehicle and equipment maintenance
- Loading and unloading of dry bulk materials or liquids
- Liquid storage tanks
- Outdoor manufacturing and processing
- Outdoor storage of significant materials
- Waste treatment, storage, or disposal including waste ponds, dumpsters, and solid waste storage or management
- Dust or particulate generating processes, including dust collection devices and vents
- Contamination of rooftops by pollution control devices
Select and Plan/Modify
Permit-required control measures must be included in the SWPPP to control the impact of industrial processes on stormwater.
The permit requires the facility to implement a set of control measures at the facility:
- Good housekeeping
- Eliminating and reducing exposure
- Salt storage (if present)
- Erosion prevention and sediment control
- Chemical additive use
- Management of runoff
- Facility inspection
- Maintenance of equipment and best management practices(BMPs)
- Elimination of unauthorized non-stormwater discharges
- Spill prevention and response
- Mercury minimization plan
- Employee training
Best Management Practices (BMPs)
The SWPPP includes the site-specific strategies that the facility has chosen as control measures required by the permit. These strategies are termed ?Best Management Practices? (BMPs).
- Some BMPs involve modification of processes and behaviors, such as:
- Standard operating procedures (SOPs)
- Decision to perform work or store materials indoors
- Some site-specific solutions involve installation of ?things? to prevent contact or treat stormwater , such as:
- Rain gardens
- Grass swales/vegetation ahead of storm inlet
- Loading and unloading of dry bulk materials or liquids
Meeting permit requirements may involve making changes to pre-existing maintenance schedules, purchasing equipment and/or supplies, creating SOPs for certain procedures, or conducting training.
After the assessment of the facility activities and materials has been completed and the site-specific strategies have been selected, the SWPPP is implemented at the facility.
The SWPPP is intended to be:
- A description of the activities and significant materials on-site that may impact stormwater
- A description of how stormwater is protected from activities and materials
- A ?living document? reflecting current conditions
- An extension of the permit -- the permit obligates the facility to follow the plan
After the SWPPP is implemented, the permit requires verification that the selected BMPs are in place, functional, and adequate to control pollutants in stormwater.
To verify, the permit requires:
- Monthly inspections
- Benchmark monitoring of stormwater
Stormwater samples (four or more) are taken and analyzed for sector-specific pollutants to verify that selected practices are quantitatively protective of downstream water.
Sample results are compared to permit-identified sector-specific benchmark values.
- If values are below benchmark values, no additional monitoring is required (unless activities change).
- If values exceed the benchmark, management changes to prevent cross-contamination must be intensified.
- Additional monitoring is required to verify that the additional management practices reduce pollutants to a safe level.
- Re-assesment against benchmark values must be completed and adjustments made to practices as directed by the data.
Resources and Documents
MPCA Industrial Stormwater Program Information
Fleet Services Facility
Como Recycling Facility
SE Steam Plant
UMTC-SE Steam Plant
Coleraine Minerals Research Lab