A sinkhole filter for protection of karst groundwater

Excerpt

Protection of groundwater quality in karst regions presents land and resource managers with special challenges. About one-quarter of the world's water supply comes from karst sources. Forty percent of the United States east of Tulsa, Oklahoma, is karst. A disproportionately high amount of agricultural production occurs on the fertile karst soils of the Appalachian region. Contaminants such as sediment, nitrate, and pathogens rapidly reach the shallow groundwater in Appalachian karst through the region's extensive network of sinkholes and sinking streams. The sinkholes often provide direct entry points to the underground system of caves and conduits that rapidly move water and contaminants great distances in a short time. The intimate relation between surface processes and groundwater requires a suite of best management practices tailored to site-specific settings to effectively protect groundwater resources in karst areas.

A sinkhole filter designed by the USDA Natural Resources Conservation Service (NRCS) in West Virginia was tested for its effectiveness in removing nitrate and fecal bacteria from surface water before it reached the groundwater under grazed lands. The sinkhole filter is composed of a gradient of sizes of crushed rock and filter fabric to filter water that runs into a vertical pipe located in the throat …