By Larry B. Dendy
A statewide group of water-quality experts says municipalities can significantly reduce and control the flow of polluted water from paved surfaces in new developments through such steps as changing patterns of development and land use, cutting back on non-porous pavement, encouraging walking and bicycling, and cleansing water through natural systems.
Suggestions offered
These are among suggestions in the report issued by the task force, which included developers and business representatives, elected officials, planning commission members, and representatives of the Georgia Conservancy and the Sierra Club. The task force was organized by faculty in UGA's School of Environmental Design with a grant from the Georgia Department of Natural Resources.
Scott Weinberg, an environmental design professor and task-force member, is making presentations on the task-force report to planning and zoning officials and others involved in development around the state.
"Many municipalities have somewhat blindly adapted codes from other cities or counties without really considering their impacts," says David Nichols, associate professor of environmental design and coordinator of the project. "We hope to get these officials to examine their own local land-development codes more closely, and to consider the adverse impacts those codes create. Then they may be more likely to adopt some of the proposed provisions."
Urban runoff, also known as "non-point source pollution," is contaminated water that drains from impervious surfaces such as building roofs, driveways, streets and parking lots into urban streams, riparian areas and wetlands.
"New land-development activities typically have very adverse impacts on surface-stream water quality," says Nichols. "Many existing land development codes unintentionally contribute to urban sprawl, higher vehicular traffic volumes, higher traffic speeds and decreased environmental quality."
Adaptable provisions
The task force is offering ideas that municipalities can incorporate into land codes when planning new developments. The report contains nearly two dozen provisions that municipalities can adapt and incorporate into local ordinances governing zoning, subdivisions, erosion and sediment control, drainage and design standards for new developments.
The suggestions range from relatively simple steps such as identifying swales and drainage outlets with educational signs, to fundamentally changing development patterns through density zoning, or by restricting certain types of construction to specified areas.
The report notes that, in undisturbed environments, water is cleaned naturally by plants, soil and microorganisms that decompose and filter out pollutants. But in urban areas the miles of impervious surfaces become "collection pans and discharge chutes" for stormwater runoff dirtied by oil, metals, pesticides and other pollutants.
This water flushes into urban streams and wetlands, eroding soil and stream banks, destroying habitats, harming fish and other aquatic animals, and threatening underground water supplies.
Impervious surfaces are a necessary evil of modern urban life, according to the report. Residences on two-acre lots typically have 12 percent impervious cover in roofs, driveways and sidewalks. Coverage peaks at nearly 100 percent in concrete- and asphalt-blanketed shopping centers and industrial and office complexes.
But it takes only a small amount of impervious cover to harm the health of streams and wetlands, the report warns. Ten percent coverage can cause significant damage; severe degradation is almost unavoidable when coverage exceeds 30 percent.
