Construction stormwater best management practice – Site stabilization

Site stabilization

NPDES/SDS Construction Stormwater permit requirements

Improperly treated and untreated runoff from exposed soils of a construction site can cause soil erosion and sedimentation problems resulting in the pollution of lakes, rivers, and other water bodies. This factsheet provides guidance on stabilizing a construction site to protect the quality of our water resources.

The erosion process

Subsoil erosion at a construction site

Erosion is the natural process in which soil and rock material is weathered and carried away by wind, rain, snow or ice. Factors such as rainfall, climate, location, and soil type that influence erosion.

Construction activities increase the ability of soil to erode once the vegetation and the top soil are removed. When the subsoil is exposed to the elements, the soil can erode very quickly. Wind and rain carry the soil off the construction site and sediment is deposited into our surface waters. This causes adverse effects on the quality of our water and to the health of aquatic life. Sediment runoff often carries additional pollutants such as nutrients, petroleum products, fecal matter and other contaminates from construction sites that further impact our lakes and rivers. It has been shown that it is far less costly to prevent erosion than to attempt to mitigate the effects of erosion after it has occurred. Through proper use of best management practices (BMPs), including temporary and permanent covers to stabilize soils along with other practices to prevent erosion; such as the use of construction phasing, horizontal slope grading, vegetative buffers and water diversions, these effects can be substantially minimized.

What is required by the NPDES/SDS Construction Stormwater permit?

The National Pollutant Discharge Elimination System (NPDES)/State Disposal System (SDS) Construction Stormwater permit identifies certain site requirements in regard to erosion prevention that, if utilized properly along with all other BMPs required by the permit, can effectively control erosion and sediment problems on a construction site.

Site stabilization is the process of implementing specific BMPs for the purpose of preventing soil from eroding. BMPs utilized for this purpose involve establishing a cover of some type over the exposed soils such as mulch, staked sod, riprap, erosion control blankets, or other material that prevents soil from eroding. Covering the soil with seed only, is not considered a stabilization practice. Mulch needs to be applied with the seed to stabilize the soil until the vegetation is established.

Sediment control BMPs, such as silt fence, rock checks, bio rolls, drainage swales, sediment traps or perimeter controls are utilized along with the soil stabilization BMPs. Perimeter controls are used to trap sediment prior to leaving the site, but alone are not considered soil stabilization practices.