Polluted stormwater runoff from construction sites has been identified as a major source of water pollution in Nevada and all developing areas. It jeopardizes the quality of our local waterways and can pose a serious threat to the health of our aquatic ecosystems. Best Management Practices, or BMPs, can reduce pollution discharges from your construction site. Compliance with stormwater regulations can be accomplished through simple, consistent measures. BMPs should be installed per manufacturers recommendations and inspected weekly and after each significant storm event. Any required repairs should be made immediately. For more information, see the Las Vegas Valley Construction Site Best Management Practices Guidance Manual.
Below are some examples of good and bad BMP practices.
Silt fences are used as a sediment control practice. Silt fences are intended to be installed where sediment-laden water can pond, thus allowing the sediment to fall out of suspension and separate from the runoff. It is not intended to be an erosion control practice. Improperly applied or installed silt fences can increase erosion. Silt fences should be constructed at the edge of the construction site parameter. Silt fences and filter barriers should be inspected weekly and after each significant storm event. Any required repairs should be made immediately.
Straw waddles or fiber rolls can also be used as a sediment control practice. They are intended to be installed where sediment-laden water can pond, thus allowing the sediment to separate from the runoff. It is not intended to be an erosion control practice. Straw waddles and fiber rolls should be installed at the edge of the construction site perimeter or to protect stockpiled materials. They should be inspected weekly and after each significant storm event. Any required repairs should be made immediately.
Concrete washout pits should be used for cleaning concrete equipment. Washout stations can be a plastic lined temporary pit or bermed area designed with sufficient volume to completely contain all liquid and waste concrete materials plus enough capacity for rainwater. The designated area should be located away from storm drain inlets and watercourses. For small cleaning jobs, manually rinse equipment into a wheelbarrow, plastic bucket or pail, and then empty the bucket into the concrete washout area.
Stormwater Detention/retention ponds are erosion control structures commonly installed to prevent erosion and to keep stormwater on construction sites. These structures control erosion by diverting water flows from erosion prone areas. The topography of the erosion prone area must be suitable for the installation of a detention/retention basin system.
Spill containment should be implemented anytime chemicals and/or hazardous substances are stored in drums or tanks. Substances may include, but are not limited to fuels, lubricants, soil binders, paints, solvents, coolants, and sewage. Spills of materials or chemicals should be contained and cleaned up immediately. Secondary containment systems must be able to hold the volume of the largest container in the storage area, plus provide sufficient additional capacity for storm events.
Stockpile BMPs must be implemented whenever there is a potential for transport of materials by a water source (forecast precipitation or any non-storm water runoff). If possible, place stockpiles at the back of lots. Protect stockpiles from stormwater run-on using a temporary perimeter sediment barrier such as berms, silt fences, fiber rolls, covers, or sand/gravel bags. Keep stockpiles organized and surrounding areas clean. Implement dust control practices as appropriate for stockpiled material.
Bagged materials such as cold patch, concrete mix, and other materials should be stored on pallets and under cover in an area where they will not be damaged, ifpossible in a garage or in a Conex box. Open bags or bags with holes should be stored so that material is contained and will not spill onto the ground.
This picture demonstrates excessive track-out at the entrance of a construction site. Implementing track-out controls can reduce offsite tracking of sediment and other pollutants. Areas of track-out should be cleaned-up by sweeping or vacuuming. Limit the points of entrance/exit to the construction site and require all employees, subcontractors and others to use them. Implement construction access stabilization using aggregate or constructed/manufactured steel plates with ribs for entrance/exit access.
This picture demonstrates how a poorly maintained drop inlet is one of the leading causes of sediment entering the storm drain system. Gravel bags, silt sacks or dandy bags should be used to intercept runoff, reduce flow velocity, and provide some sediment removal from the construction site. It is important to maintain and inspect inlet protection devices after each storm event, and routinely throughout the construction project. Sediment bags that are damaged or ripped do not function as designed and can lead to discharges to the storm sewer system.
Storm drain inlet protection is not permitted in a public street that has been accepted by a public agency. BMPs can slow the flow of stormwater runoff entering the storm drain inlet can result in ponding into road traffic or onto erodible surfaces or slopes, or overflowing onto the sidewalk. Protection of storm drain inlets are only allowed within the boundary of the construction site itself where sediment laden surface runoff may enter a storm drain inlet and watercourses. Blocking a storm drain inlet with surface BMPs in the public right-of-way outside the permitted project boundary is only allowed temporarily during street washing activities. Once street washing is completed BMPs must be removed.
This picture demonstrates a poorly maintained silt fence. A properly installed silt fence holds water back long enough so that much of the sediment from runoff settles out on the construction site. Posts for silt fences should be secured on the downstream side of the fence. The bottom of the silt fence should be secured. Silt fences and filter barriers should be inspected weekly and after each significant storm event. Any required repairs should be made immediately.
This picture demonstrates poor trash removal at a construction site. Practice good housekeeping and keep your site clean. Collect site trash regularly, especially before rainy or windy conditions. It is important to perform routine inspections of your site, including storage areas, dumpsters, stockpiles and other areas where trash and debris are collected. Close trashcan lids and dumpster covers before rainy or windy conditions.
This picture demonstrates how exposed construction materials and chemicals are susceptible to runoff and may enter a storm drain system. Practice good housekeeping and keep your site clean.
This picture demonstrates how unprotected fuel, oil, or chemical tanks without secondary containment is the leading cause of contaminated soil. Spill control procedures must be implemented anytime chemicals and/or hazardous substances are stored on site. All contaminated soils must be removed and managed as hazardous substances, if applicable, in accordance with applicable laws and regulations.
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