Sediment and excess nutrients continue to be two of the top five pollutants in the waters of the United States. To help limit these and other pollutants from entering waterbodies, the Environmental Protection Agency (EPA) requires operators of construction activities that disturb more than an acre of land, those that will be part of a common plan that will ultimately disturb more than an acre and certain other construction activities that may impact environmentally sensitive areas to obtain a National Pollutant Discharge Elimination System (NPDES) permit.
Stormwater permitting for construction falls under the EPA’s NPDES permitting structure. Most operators (any party associated with a construction project who has operational control over construction plans, specifications, modifications or compliance) are eligible to apply for a construction general permit (CGP) unless there are circumstances that require them to develop a more specific NPDES permit.
Before construction activities begin, operators must submit a Notice of Intent (NOI). Operators must also have a Stormwater Pollution Prevention Plan (SWPPP) that outlines and describes the control measures that will be used to control sediment, erosion and other sources of water pollution. Plans must also include procedures and schedules for inspections, maintenance and any corrective actions.
Plans must be specific to the construction activities that will be conducted and must identify how the best practices that they have chosen will prevent water pollution. They must also address employee training and assign responsibilities for compliance with the control measures documented in the plan.
The EPA encourages operators to determine and use best management practices to prevent pollution. As such, the EPA does not require the use of any specific technology or technique. They do, however, require that plans address the following applicable activities.
Equipment and Vehicle Fueling and Maintenance
Trucks, cranes, backhoes, bulldozers and many other forms of heavy equipment are commonly used in construction activities. Most of these items contain oil and either gasoline or diesel fuel. When hydraulic lines break or fuel is spilled, it can impact both soil and water. Plans and practices to prevent pollution from vehicles and equipment can include:
Some larger construction sites are also subject to the EPA’s Spill Prevention Control and Countermeasures (SPCC) rule because they store oil or oil products more than 1,320 gallons aboveground or 42,000 gallons underground. When this is the case, SPCC planning elements can be implemented as part of the SWPPP.
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Equipment and Vehicle Washing
Sediment on tires or belts needs to be removed before vehicles or equipment leave a construction site so that it is not tracked onto sidewalks or roads. Any residual sediment that does get tracked out must be shoveled, swept or vacuumed by the end of the same business day.
Establishing and restricting vehicle and equipment exits through designated points can help control trackout. It can also facilitate the use of wash-down areas that effectively capture sediment and allow water to be collected. If soaps, detergents or solvents will be used for cleaning, wash-down areas can also be used to channel these to basins for settling, recovery, recycling or proper disposal so that they are not discharged.
Plans also need to describe how the wastewater from concrete, stucco and paint washouts will be handled. These activities may be handled in the same area as other equipment wash-downs or in other designated areas, but they must be done in a designated area that is controlled to prevent discharges.
Protecting Storm Drain Inlets and Perimeters
Precipitation can quickly carry loose soil into storm drain inlets where it then travels to streams, rivers and/or lakes. This sediment causes a variety of water quality problems. Sediment can also fill drain inlets, causing flooding problems.
Storm drain filtering inserts can be installed to passively collect sediment so that it is not released into waterways. Drain filtering socks can be placed around drains to provide additional protection.
Loose sediment doesn’t always make its way to storm drains. It can also be washed beyond the perimeters of construction areas and directly into waterways or onto shorelines. When construction activities take place near a water source, a 50-foot undisturbed natural buffer and/or other erosion and sediment control devices must be utilized to prevent sediment from reaching water.
Use of Fertilizers and Other Stabilization Measures
The proper use of fertilizers can encourage grass or other landscaping materials to grow so that dust and erosion can be minimized during or following construction activities. Improper or overuse can cause residues to be discharged into water causing algae blooms and compromising water quality.
When fertilizers will be used, plans should detail how and when they will be applied. Applications should not be made before heavy rains, in off-seasons or when the ground is frozen.
In addition to fertilizers, seeding, mulching, sodding and other erosion control methods should be used to stabilize the ground during and after construction activities. Some areas have special requirements for these activities, especially in drought-stricken and other environmentally sensitive areas.
Storing, Handing and Disposing of Building Materials and Wastes
Managing building materials and wastes properly minimizes losses and helps to prevent releases to the environment. Best practices include:
- Covering building materials to minimize exposure to rain or snow
- Storing liquids in sealed containers
- Providing secondary containment in fluid transfer and waste collection areas
- Stocking spill response supplies in fluid transfer, storage and waste collection areas
- Segregating construction, sanitary and hazardous wastes for proper recycling or disposal
- Keeping the lids of all waste collection containers closed when not in use
- Keeping stockpiles away from the perimeters of the construction site
Sediment Basins and Treatment Chemicals
Sediment basins can be utilized before and after construction projects to channel stormwater and debris into a designated area so that the sediment can settle out of stormwater before it is discharged. When sediment basins are used, it is important to size them properly to prevent them from overfilling. It is also important to have a plan for removing accumulated sediment before it reaches one half of the designed capacity.
In addition to collecting sediment, some basins can also be designed to collect residual treatment chemicals or pesticides. In some cases, the basins allow for dewatering. In others, they facilitate pumping the mixture for recycling or disposal.
Spill Prevention and Response Procedures
Spills are never a part of planned construction activities, but when they do occur, it is essential to have plans and equipment in place to clean them up quickly and effectively. Plans must also list the phone number for the National Response Center (NRC) as well as state and local authorities who may need to be notified if a release exceeds a reportable quantity.
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Having plans in place, communicating those plans to employees and maintaining accountability for compliance will help ensure that the conditions specified in construction permits are met. Like all plans, construction SWPPPs are living documents that need to be updated as activities change or as phases are completed. Utilizing best management practices will help prevent pollution and maintain the quality of our nation’s waters.