Soil erosion and sediment loss from construction sites has been documented as a major source of water pollution (refer to USGS study). Bare soil exposed to a rain event can become quickly eroded, leading to sediment that moves into adjacent storm sewers or lakes and streams.
Soil erosion and sedimentation involves three steps:
- soil particle detachment
- transportation
- deposition
Erosion control practices are typically designed to prevent detachment and transportation of soil particles while sediment control is designed to trap eroding soil on-site. Erosion and sediment control go hand-in-hand, but given the choices of methods and materials, it is better to prevent erosion in the first place than try to control sediment after erosion occurs.
The loss of soil from agricultural lands has long been recognized as a significant world problem affecting food production and water quality (read story from Cornell news service). Just as agricultural soil erosion results in lower yields and poor plant growth, urban soil erosion reduces the likelihood of healthy landscape plantings. This is especially true during the urbanization process where mass grading destroys the natural soil profile and causes significant loss of topsoil.
Initial EPA regulations implemented to reduce erosion and sediment focused on sites larger than five acres. Current regulations include sites down to one acre in an effort to minimize the collective significance of water quality degradation caused by small sites.
A Stormwater Pollution Prevention Plan (SWPPP) is required by the Nebraska Department of Environmental Quality (NDEQ) for projects that disturb site topography, existing soil cover (both vegetative and non-vegetative) and/or soil topography on one or more acres of land. Less than one acre of total land area can also fall under regulation if it is part of a larger Common Plan of Development or Sale that will ultimately disturb one acre or more and includes all areas of Support Activity.
The design, implementation and monitoring of a SWPPP involves a significant amount of expertise and resources if the plan is to be successful. Substantial fines and penalties can be levied by regulatory agencies from the EPA down to local municipalities if construction site runoff is not addressed (see original story from June 2008 AP news release). The cost of noncompliance has been set high. Fortunately a wide variety of resources exist that provide information on SWPPP development and implementation, including:
Environmental Protection Agency - extensive information on SWPPP
NDEQ Fact Sheet for NPDES Permit Authorizing Stormwater Discharges Associated with Construction Sites (17 pages,* pdf format)
Information presented within the Stormwater Management section of this Water Web site has been reviewed by University of Nebraska - Lincoln Stormwater Management Team members Katie Pekarek, Kelly Feehan, Thomas Franti, Steven Rodie and Richard Sutton.
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