The construction of large and small infrastructure and capital projects has increased significantly over the last several years. Roads and bridges are being constructed or expanded and many industrial facilities, especially in the Gulf South, are breaking ground to build large complexes or expand existing ones. Obviously, this activity will expose sediments within the construction area and may, during rainfall events, create storm water run-off laden with those sediments. These pollutants can cause problems in nearby streams, lakes and bayous.
Best management practices applicable to construction activities, including clearing, grading and excavation, have been established over the years. The practices apply to construction in areas over five acres and, in some cases, to areas less than five acres. Although they have been in place for several years, it is best to review these practices from time to time to ensure compliance with existing rules and minimize any impact to the environment surrounding the construction site.
Several best management practices have been established for construction activities. These include erosion and sediment controls, soil stabilization, and other pollution prevention measures.
Erosion and sediment controls must be designed, installed, and maintained in order to minimize the discharge of pollutants. At a minimum, these controls should address the volume and velocity of storm water run-off, minimize the amount of soil exposed during construction activity, and minimize the disturbance of steep slopes. One common method of sediment control is the installation of silt fences, sometime in conjunction with hay bales, to maintain sediments within the construction area. As an added level of protection, turbidity barriers or booms can be used in nearby waterways.
These controls may also include maintaining natural buffers or a vegetated area around the construction area and directing stormwater to flow through or over these natural buffers. The vegetation acts as a natural barrier to reduce the amount of pollutants flowing into nearby waterways.
Stabilization of disturbed soils should be initiated immediately whenever clearing, grading, excavating, or other earth disturbing activities on any portion of the construction site have permanently ceased or will be suspended for over fourteen days. The compaction of soil minimizes the amount of sediment that can be picked up and carried during a rainfall event.
There are also a few common sense pollution prevention measures that can be taken. For example, directing any wash water from equipment and vehicle washing or wheel wash water to a sediment basin will allow the heavier sediments to drop out of the water prior to discharge. Additionally, covering building materials, trash, landscape materials, fertilizers, pesticides, herbicides, detergents, and other materials will ensure that these materials, or sediments attached to them, will not flow from them during a rainfall event.
There are several types of discharges from construction activities that are prohibited. For example, the discharge of wastewater from the washout of concrete, unless managed by an appropriate control, and any discharge of wastewater from the washout and cleanout of paint, oils, curing compounds, and other construction materials. Obviously, the discharge of fuels, oils, soaps, or solvents used in vehicle and equipment maintenance and washing is not allowed.
In short, employing best management practices at a construction sites will minimize the discharge of pollutants to nearby waterways. Not only will you be in compliance, but you will help preserve the natural beauty and integrity of our waterways.