Best Practices in Stormwater Management & Regulatory Compliance for Industrial Facilities and Construction Sites

What is Stormwater?

Stormwater is water generated by heavy precipitation including rain, hail and snow. Stormwater may infiltrate permeable surfaces such as loose soil, organic material and gravel/stones; or flow atop solid paved surfaces such as asphalt, concrete and compacted soil. Stormwater that infiltrates soil has the potential to impact subsurface groundwater. Stormwater follows regional topography when flowing atop solid surfaces. Catch basins, storm drains, culverts, subsurface piping and retention ponds are all engineering techniques used to control the flow of stormwater. Most stormwater ultimately ends up in wetlands, streams, rivers, ponds, lakes or oceans. However, some stormwater is collected, treated and re-used for irrigation, drinking water, cooling, flushing and washing purposes.

The type of ground surface significantly effects the rate at which stormwater can infiltrate the ground. A forested area can infiltrate as many as eighteen (18) inches of stormwater an hour and the average residential lawn can infiltrate up to two (2) inches of stormwater an hour, while paved and solid surfaces are unable to infiltrate stormwater. A 2,000 square-foot area of solid impervious surfaces generates approximately 1,246 gallons of stormwater during a typical rainstorm.

Why Stormwater Management is Important

Without proper stormwater management, the risk of flooding in homes and businesses increases. Areas especially prone to stormwater flooding include densely populated areas where significant development creates less permeable surfaces for stormwater to infiltrate. Known as urban flooding, these conditions can cause basement flooding, sewer backups, utility damage and roadway damage. Flooding of homes and building structures can lead to additional environmental issues such as mold growth and poor air quality. In addition to the above described risks of improper stormwater management, stormwater pollution is another risk that must be properly managed.

Stormwater Pollution: When There’s More than Water in the Stream

As stormwater flows over natural and human-made surfaces, it can collect pollutants such as sediment/sand, road salt, oil and grease, fertilizer, pesticides/herbicides, metals and trash. Polluted stormwater may eventually discharge into surface water bodies, causing further contamination and the spread of pollutants. For example, studies have shown that chemicals used in typical lawncare fertilizer that reach lakes and ponds from stormwater runoff causes nutrient loading. Nutrient loading can result in harmful aquatic algal blooms, which deplete oxygen levels in the freshwater bodies, making conditions stressful for aquatic wildlife.

Stormwater Regulations in the United States

Stormwater is regulated by the United States Environmental Protection Agency (USEPA) pursuant to the Clean Water Act (CWA). The CWA establishes the basic structure for regulating:

• discharges of pollutants into the waters of the United States
• quality standards for surface water

Established in 1948 as the Federal Water Pollution Control Act, the legislation was significantly expanded and reorganized in 1972.

The USEPA’s National Pollution Discharge Elimination Systems (NPDES) permit program regulates stormwater discharges. The USEPA has authorized many states to issue NPDES permits that comply with the CWA. Many industrial facilities, construction sites larger than one (1) acre and properties with municipal separate storm sewer systems are subject to the CWA and must hold an NPDES stormwater discharge permit to discharge stormwater. Additionally, a Stormwater Pollution Prevention Plan (SWPPP) or a Stormwater Management Plan (SWMP) is required as a component of the permit. SWPPPs and SWMPs document the controls and best management practices in place for mitigating the discharge of pollutants via stormwater runoff, as well as inspection and monitoring programs. Ongoing monitoring requirements and frequency varies by industrial sector and include:

• visual inspections
• indicator monitoring
• benchmark monitoring
• effluent limitation monitoring

Organizations and facilities discharging stormwater under a federal or state permit must also follow strict reporting requirements, including submitting monitoring and compliance reports to the applicable permitting authority.

Best Management Practices for Construction Sites and Industrial Facilities

Construction sites contribute to increased stormwater pollution through the spread of sediments and accidental vehicle fluids discharges/overfills. During times of heavy precipitation at construction sites, water runs freely across barren and compacted ground surfaces collecting sediment and soil that become suspended within the stormwater runoff. To mitigate the unintended consequences of this stormwater pollution, the following best management practices for construction sites include:

• Installing silt fencing and/or sandbags around the perimeter of the site to prevent sediments and other contaminants from leaving the property
• Building a rock/stone entrance for construction vehicles to prevent sediments leaving the property via vehicle tires
• Covering soil stockpiles during precipitation events and windy conditions
• Refueling vehicles within a designated refueling area. Ensure that a spill kit and containment materials are nearby in the event of an accidental overfill
• Creating a stormwater retention pond at the lowest portion of the site and channeling stormwater runoff to flow into this area

Industrial facilities that manufacture, process, blend, store or otherwise utilize oil and/or hazardous materials (OHM) are common contributors to stormwater pollution. Routine activities conducted by these facilities can result in inadvertent OHM releases, which allows OHM to be subsequently collected and transported by stormwater. The following best management practices should be utilized by industrial facilities to reduce the risk of stormwater pollution:

• Ensure that the facility maintains an effective and operational stormwater management system that collects and channels stormwater to flow through a designated system. Consider installing a treatment system to filter/remove potential contaminants.
• Maintain stormwater drainage infrastructure including catch basins, culverts and outfalls. Stormwater entry points should remain free of debris.
• Immediately address any unauthorized spills or discharges of OHM at the facility to prevent contaminants from migrating off-site via stormwater.
• Use landscaping, vegetation and hardscaping to guide stormwater runoff to the established management system and to re-vegetate any disturbed areas at the facility.
• Periodically utilize street sweepers to remove sediments and other contaminants from solid surfaces at the site.

Why is Complying with Stormwater Regulations Important?

Industrial facilities and construction sites have an operational duty to reduce the amount of pollutants entering the environment via stormwater runoff. Failure to take the necessary steps to comply with federal, state and local stormwater regulations can have costly implications for the responsible party. Violating a facility’s stormwater discharge permit may result in the USEPA or authorized state issuing an administrative order requiring corrective actions be performed to address the violation(s). Additionally, the USEPA or authorized states may enact civil penalties against the organization responsible in the amount of up to $56,460 per day per violation, or criminal fines in the amount of $500,000 per day per violation. Finally, the stormwater discharge permit can be revoked, preventing the authorized discharge of stormwater.

To learn more about stormwater management and regulatory compliance, please contact Coleman Macuch, Senior Project Manager at cmacuch@vertexeng.com.