Industrial Stormwater Best Management Practices
Stormwater is the water that originates from precipitation such as heavy rain or meltwater from hail or snow. Many industrial facilities introduce materials to stormwater through the outdoor storage, handling, and transfer of product materials, by-products, and waste products. These industrial products often contain pollutants such as metals, oil, and grease which negatively impact stormwater runoff. Additionally, industrial activities can cause erosion and sediment problems that also impact stormwater runoff.
Best Management Practices (BMPs) are pollution control measures designed to prevent or reduce the effects of pollutants in stormwater runoff from industrial stormwater discharges. Some BMPs are specific and well-defined, while others are general in nature. Facilities determine which BMPs to use based on permit requirements, the facility’s specific industrial materials, and the facility’s specific activities.
BMPs should be considered as a system or series of activities that may include non-structural and structural BMPs.
Non-structural BMPs are management techniques implemented through simple daily duties. The facility identifies and implements site-specific BMPs which have a direct impact on the day-to-day operations. Some of the more common non-structural BMPs include good housekeeping, eliminating and reducing exposure, management of salt and/or industrial storage piles, management of runoff including soil and erosion prevention, and dust control.
Structural BMP options vary depending on the pollutants each can treat, efficiency, maintenance issues and limitations of controls. Structural BMPs are more technical in nature and advanced technical expertise is required to make informed decisions about implementing structural stormwater BMPs. It
is suggested to consult with a licensed professional engineer early in the decision process. Common structural BMPs include sedimentation systems (e.g. retention ponds), infiltration systems (e.g. stormwater trenches), filtration systems (e.g. vegetative filters), and proprietary systems (e.g. vortex separators).
Federal regulations require stormwater discharges associated with specific categories of industrial activity to be covered under a National Pollutant Discharge Elimination System (NPDES) permit. EPA has developed a fact sheet for each of the 29 industrial sectors regulated by the NPDES permits. Each fact sheet describes the types of facilities included in the sector, typical pollutants associated with the sector, and types of stormwater control measures used to minimize the discharge of the pollutants. These BMP fact sheets are a great starting point for determining the various pollutants which cause stormwater pollution at a facility and provide BMPs that are applicable to a specific industrial facility operation.
Regular inspections of a facility’s BMPs are required by the NPDES permits. These inspections are integral in determining if structural and nonstructural BMPs are properly functioning, require maintenance, or need to be changed. Inspections also determine the accuracy of the facility’s written stormwater plan, as all observations and any changes made as a result of the inspections must be documented in the written plan.
For more information on BMPs for stormwater, check out EPA.gov or reach out to your Cornerstone Team directly.
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Stormwater "Red Flags"
Many years ago, I interned for the local County Health Department and assisted them with water quality monitoring. The department monitored the water quality from twelve points along the rivers and streams in the county. Rain or shine, I headed out every Wednesday morning to collect samples. At each location, I pulled on the hip waders and walked a few meters from the shore to measure oxygen levels and collect a sample for the lab. Every week I plated petri dishes and counted E. coli colonies. Some days the water quality of the river was excellent and other days the bacteria levels (E. coli) in the river were dangerously high. What spiked the levels of bacteria levels in a body of water that moved over 30,000 cubic feet per minute? Rainfall, or more accurately: the pollution that the rainfall carried.
I later found out that some of the sampling locations were near animal farms, hence the E. coli. Water is often called the ‘universal solvent’ because more substances dissolve in water than in any other liquid. The Clean Water Act defines the term “pollutant” broadly.
“[A pollutant] includes any type of industrial, municipal, and agricultural waste discharged into water. Some examples are dredged soil, solid waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal, and agricultural waste.”
The Environmental Protection Agency and state governments work hard to protect waters through the implementation of the National Pollutant Discharge Elimination System (NPDES) permit program. Many industries obtain NPDES general stormwater permit coverage if they discharge into water of the United States. Sampling from a site’s discharge point(s) is an important part of the general NPDES permit. The data is compared with benchmark thresholds as an indicator of the effectiveness of the permit and stormwater control measures. Unlike an air permit, a stormwater sample result that exceeds one of the benchmark thresholds is often considered a “red flag” as opposed to a violation.
No one wants to have a “red flag” when they submit their stormwater results, but it may point to a problem with an exposed pollutant source at your site or a stormwater control measure that is not working correctly. Stormwater regulations protect our waters and, ultimately, protect our drinking water and health. As cliché as this sounds, our actions upstream impact our water downstream. Whether it’s general housekeeping at your facility or making sure a driver safely transfers material from your site, every action matters. Monitoring the exterior of your facility weekly is a great activity to ensure your site is not unintentionally polluting. Atypical events such as a leak or spill that was not cleaned up can be caught in time before the rainfall.
Remember that rivers, despite their size and capacity, can be significantly impacted by our actions. Let’s minimize the pollution the rain carries to keep the rivers healthy.