Stormwater Case Studies Search Results
Case Study Location: Wisconsin: Dane County
Case Study Title: County-wide Erosion Control Model Ordinance and Standards
Minimum Control Measure: Construction site stormwater runoff control
Location: Wisconsin: Dane County
The Dane County Lakes and Watershed Commission developed a comprehensive erosion control and stormwater management ordinance, which the Dane County Board of Supervisors adopted in 2002. The ordinance includes countywide standards to address the quality and quantity of water that runs off construction sites and farms. These standards address erosion and sediment control, post-construction controls, and thermal pollution control. The program has 4.5 full-time equivalents and is funded through a General Fund and permit fee revenue.
The county's ordinance requires an erosion control permit, generally for land disturbance of more than 4,000 square feet, and a stormwater control permit, generally for development that results in the cumulative addition of 20,000 square feet of impervious surface to the site.
The ordinance builds on standards previously used in the county (adopted in 1995) that limit the total off-site soil loss for exposed areas to an annual cumulative soil loss rate not to exceed 7.5 tons per acre. The county has developed a Universal Soil Loss Equation spreadsheet to help estimate soil loss from construction sites required to obtain an erosion control permit. The Dane County Land Conservation Department reviews erosion control plans for accuracy and compliance with the ordinance.
For projects required to obtain a stormwater control permit, the county requires the development of a stormwater management plan. The plan should include a drainage map and site map showing erosion control and stormwater practices, methods to control oil and grease, and a maintenance plan for permanent stormwater management practices.
The stormwater management plan is also required to meet the following performance standards:
Dane County administers the ordinance in unincorporated areas in the county, as well as in cities and villages that do not adopt or administer standards that are at least as restrictive. To ensure that all cities and villages have incorporated adequate standards, the county has developed a model ordinance for them to use, certifies the programs adequate, and regularly audits the entities to ensure program implementation. According to the program contact, municipalities have been very cooperative in correcting any concerns raised during audits and in general are complying. The county also provides technical and programmatic assistance to independent entities if they need assistance administering their programs. In addition, the county provides checklists, worksheets, templates, and guidance documents to ensure that developers and contractors fully understand the requirements of the ordinance and submit the necessary documentation when applying for a permit.
Effectiveness of the Program
To collect baseline data on the effectiveness of the program, the County partnered with USGS to monitor water quality from two small construction sites (Soil Erosion from Two Small Construction Sites, Dane County, Wisconsin, USGS Fact Sheet FS-109-00, August 2000 ). Researchers evaluated the water quality impacts from a small residential and a small commercial construction site, both under 5 acres, that did not use erosion and sediment controls. The study found that sediment loads from the two monitored construction sites were 10 times larger than typical loads from rural and urban land uses in Wisconsin. Total solids and suspended solids concentration data indicate that the active construction phase produced concentrations that were several orders of magnitude higher than pre- and post-construction periods. These concentrations were dramatically reduced when the site was seeded and mulched. These results support the need to design and implement erosion control plans.
The County also reviews erosion control plans for five contracted cities in the County. Out of a total of 175 sites within these cities in 2004 (as of October), the County had conducted more than 2,200 total inspections, with almost 650 verbal warnings for minor violations. Continued non-compliance or significant violations result in a written noncompliance notice; (more than 60 were issued), with 15 of these notices resulting in a recommendation to the City to pursue formal enforcement actions.
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.