Stormwater Case Studies Search Results
Case Study Location: Virginia: Arlington County
Case Study Title: Innovative Stormwater Management Standards and Mitigation
Minimum Control Measure: Post-construction stormwater management in new development and redevelopment
Location: Virginia: Arlington County
For projects that propose to disturb at least 2,500 square feet, the Arlington County, Virginia, Department of Environmental Services requires a plan of development that includes a landscape conservation plan, a stormwater management plan, and an erosion and sediment control plan. The landscape conservation plan helps ensure the health and survival of trees, while the stormwater management plan includes requirements for implementation and maintenance of best management practices (BMPs). The county has also established a Watershed Management Fund to support watershed-level solutions to urban stormwater management problems.
Arlington County is an ultra-urban county in the metropolitan Washington, DC, area. There are 7,323 people per square mile in the county, and much of the development is infill or redevelopment. In 1992 the county adopted its first Chesapeake Bay Preservation Ordinance (CBPO), as required by the Virginia Chesapeake Bay Preservation Act of 1988. This act requires all tidewater local governments to protect designated Chesapeake Bay Preservation Areas from water quality degradation. Because Arlington is an ultra-urban locality, many of the water quality impacts are caused by existing development, infill, and redevelopment. The Arlington County CBPO regulates new development and redevelopment projects in the county. It was revised in 2003 based on new state regulations, state guidance documents, and input from county staff and a local task force.
The ordinance established Resource Protection Areas (RPAs) based on several factors, such as wetlands, tidal areas, and stream buffers. The remainder of the county was deemed a Resource Management Area (RMA). Different levels of water quality protection are afforded to RPAs and RMAs. The type, size, and location of development that may occur in the county is strictly controlled by zoning and planning regulations, and the CBPO requires additional measures to protect water quality for all projects involving more than 2,500 square feet of land disturbance. These measures include
The county has developed a set of pollutant removal requirements for development sites dependent on the amount of existing and proposed impervious cover, as well as whether there are any stormwater quality BMPs on-site. The ordinance requires on-site treatment for impervious surfaces with which vehicles come into contact (e.g., parking areas, roadways, loading areas). If treatment of such areas does not meet the full pollutant removal requirements for the site, the developer is given several innovative compliance options: additional on-site treatment for the developing area, on-site treatment for off-site areas, or a monetary contribution to the county's Watershed Management Fund.
Developers may contribute $2.50 per impervious square foot of impact area (determined through the county's stormwater calculation worksheet) to the Fund in lieu of constructing on-site BMPs. The contribution rate may be updated and is to reflect the cost of providing on-site treatment, including the design, building, and maintenance of structures. According to the CBPO, the fund is used to reduce nonpoint source pollution and improve stream quality and habitat through programs which provide BMP retrofits, stabilize or restore stream valleys and steams, educate the residents of the county on methods of reducing nonpoint source pollution runoff, promote public awareness of the importance of stormwater quality, supplement county programs which provide water quality protection, provide demonstration projects, or provide water quality monitoring or analysis.
The Fund is also used to further specific projects and programs outlined in the county's Watershed Management Plan.
The Fund also receives all civil penalties paid by violators of the CBPO ($10,000 for each violation and/or $5,000 per day of noncompliance). To date, the county has not used this enforcement mechanism.
The county has developed a guidance manual to assist in determining ordinance requirements, necessary stormwater quality treatment BMPs, and the assessment of an appropriate payment into the Fund. The guidance manual also provides information about appropriate BMPs, planting recommendations, and site design. A worksheet has been developed to assist with making calculations and determining the required treatment or alternative Fund payment.
Since the revision of the ordinance in February 2003 and the increase in the Watershed Management Fund fee, the Fund has taken in about $500,000 (compared with a total of $500,000 from 1992 to 2002). The county estimates revenues of around $400,000 annually.
Additional Materials Related to this Case Study:
EPA presents this case study as an example to which Phase I and Phase II municipal stormwater programs can refer as they develop their own stormwater programs. Although EPA has reviewed the case studies, they should not be considered officially endorsed by the Agency and are not intended to represent full compliance with EPA’s stormwater Phase II minimum control measures. Each community must decide on the appropriate BMPs necessary to meet its unique permit requirements and local conditions.