During the construction process there are many ways that sediment and other pollutants can be mobilized and carried into the storm drain system and our natural waterways.
Construction projects are required to implement erosion and sediment control Best Management Practices (BMPs) to ensure that sediment (dirt, soil, mud, or sand) and chemicals stay on the site instead of being carried by stormwater into the storm drain system. Some of these BMPs are as simple as planting grass on disturbed soils to keep the soil in place. Other BMPs that must be implemented during the construction process include properly storing chemicals on the site to ensure that they are not allowed to come in contact with stormwater.
For projects that disturb at least one acre of land (43,560 square feet) a Stormwater Pollution Prevention Plan (SWPPP) is required. This document shows what BMPs are planned on site to prevent erosion and to minimize discharge of sediment and chemicals into the storm drain system.
SWPPPs are "living documents" that are modified as the construction process proceeds. As a project progresses through different phases the SWPPP is updated with appropriate BMPs for that phase of the project. Changes are also made when experience indicates that use of different BMPs would be more effective.