Six Minimum Control Measures
Stormwater Management Program
Under the National Pollutant Discharge Elimination System (NPDES) Phase II regulations, Loudoun County must prepare a stormwater management program containing elements that address the following six technical areas:
- Construction site runoff control
- Illicit discharge detection and elimination
- Pollution prevention / good housekeeping
- Post-construction runoff control
- Public education and outreach
- Public participation / involvement
Stormwater Management Plan
Each of these areas, identified as minimum control measures in the NPDES Phase II regulations, is discussed in the Loudoun County Stormwater Management Plan (PDF). For each of the minimum control measures, communities must identify best management practices (BMPs) and measurable goals that reflect the communities' choices about how to satisfy the regulatory requirements. These BMPs and goals form the basis on which the success of the Phase II program can be evaluated in each community, which is ultimately the degree to which the community is satisfying the water quality requirements of the Clean Water Act.
To assist communities, the Virginia Department of Environmental Quality (DEQ), along with the Environmental Protection Agency (EPA), has specified the minimum requirements for each of the six control measures along with recommended program elements. While Virginia's two environmental agencies, VDEQ, and the Virginia Department of Conservation and Recreation (VDCR) continue the process of developing a unified Virginia BMP manual, the EPA has developed and is continuing to revise a list of potential BMPs that communities might use to satisfy the Phase II program requirements.
Best Management Practices
To arrive at appropriate best management practices, the county engaged in an extensive assessment of the existing stormwater management operations, ordinances, and programming against the compliance requirements of the General Virginia Stormwater Management Program (VSMP).
A best management practice (BMP) is a technique, process, activity, or structure used to reduce the pollutant content of a stormwater discharge. BMPs include simple nonstructural methods, such as good housekeeping and preventive maintenance. BMPs may also include structural modifications, such as the installation of bio-retention measures. BMPs are most effective when used in combination with each other, and customized to meet the specific needs (drainage, materials, activities, etc.) of a given operation. The focus of EPA's general permits is on preventive BMPs, which limit the release of pollutants into stormwater discharges. BMPs can also function as treatment controls.