Living on Karst
A Reference Guide for Landowners in Limestone Regions
Produced by the Cave Conservancy of the Virginias, June 1997
Reducing Runoff Polution in Karst Areas
Common Runoff Pollutants
- Heavy metals (lead, copper, zinc, chromium) from gasoline, tires, corroded metal, paint, wood preservatives, and motor oil.
- Pesticides and fertilizers from yards, foundations and gardens.
- Bacteria from sewage and animal wastes.
- Soil sediments from construction sites, bare stream banks, home landscaping, and steep exposed slopes.
Prevention is the best cure. The pollution potential in karst areas is very high. Streams and surface runoff entering sinkholes and storm drain contribute to the recharge of groundwater aquifers, providing direct conduits for contaminants.
Changes in Water Flow
Urban development and growth may cause water quality problems. Stormwater management, erosion control strategies, and riparian zone management need to be carefully considered. The traditional methods of large-and small-scale development paid little attention to the number of impervious surfaces that were created, such as roofs, sidewalks, streets, and parking lots. Rain runs rapidly off of the these surfaces, turning city streams into raging torrents that cause erosion and damage property.
Bare construction sites allow large amounts of fine soil, or sediment, to erode away. Other pollutants often attach to sediment particles, and can be transported far downstream in floods, spreading their toxic effects. The silt clogs drainage ways, caves, and sinkholes, and increases community flooding problems. It prevents native aquatic plants from getting the sunlight they need, and smothers fish eggs and other oxygen-loving creatures that live on stream bottoms.
Rains wash toxic chemicals, bacteria, and silt from urban surfaces. Uncontrolled runoff causes sewage treatment plants to overflow directly into waterways. Fertilizers encourage the growth of slimy algae, and oil forms visible scum. Even heat is a pollutant. Runoff from hot pavement can make streams unbearably warm for creatures in the stream.
Basic Runoff Controls
Well-designed runoff controls can be smart, cost-effective, aesthetically pleasing, and for businesses, satisfy local requirements for green spaces. There are many easy and affordable ways to reduce harmful stormwater runoff, make your living or working environment more pleasant, and enhance property values, all at the same time.
- Maintain as large a vegetated zone as possible on drainage ways and slopes to slow runoff and filter out pollutants.
- Slow runoff by building check dams across ditches and using vegetated sinkholes to naturally detain water and allow soil and pollutants to settle out.
- Keep soil on site during construction by using silt fences, hay bales, and sedimentation basins.
- Reseed and mulch areas of exposed soil as soon as possible to reduce erosion.
- Use gravel or permeable paving materials which allow rain to penetrate the surface rather than running off directly into a stream or sinkhole.