A study of private water wells in reclaimed surface-coal-mining areas of the northern and central Appalachians shows that traces of mining-related contaminants persist in some wells, the U.S. Geological Survey (USGS) reports. These contaminants typically decreased to background levels at distances 1,000 feet or more from surface coal mines, and in wells deeper than 150 feet.
The study compared ground water quality in 58 privately owned wells downgradient of reclaimed surface coal mines to that of 25 wells in unmined areas. The comparisons were made on a large scale within and between the high-sulfur coal region in western Pennsylvania and northern West Virginia, and the low-sulfur coal region in southern West Virginia.
Surface coal mines historically have had major impacts on the quality of shallow ground water. Since about 1977, changes in mining regulations have mandated reclamation. Although state and federal regulators require water-quality monitoring in and near surface coal mines, this study examined whether post-reclamation ground-water quality near bituminous coal mines is similar to ground-water quality observed in unmined areas.
"Iron and manganese were commonly detected at concentrations exceeding U.S. EPA drinking-water standards. Although more frequently detected with sulfate, aluminum and five other constituents in water from wells in mined areas, only concentrations of iron and manganese exceeding drinking water standards are also commonly detected in water from wells in unmined areas" says Mark Kozar, a USGS hydrologist and co-author of the report.
Concentrations of radon-222, a colorless, odorless and carcinogenic gas, also were commonly detected in the wells sampled, but less frequently in mined areas than in unmined areas. According to Kozar, "Radon concentrations are generally lower in the mined areas, most likely due to fracturing of rock associated with surface mining, which allows the gas to escape."
"Unlike iron and manganese, which are regulated primarily due to problems with taste, odor or staining of plumbing fixtures, inhalation of air with elevated concentrations of radon gas poses a potential health threat, primarily lung cancer," Kozar says. "The bottom line for residents of coal-mining regions in the Appalachians is being aware of radon gas, and knowing that kits are available to test the indoor air in their homes for radon. Testing well water for iron, manganese, sulfate and bacteria is also a good idea," Kozar adds.
As part of the USGS National Water-Quality Assessment Program (NAWQA), ground-water samples were collected from the 83 wells in 1996-98. Samples were analyzed for a broad set of common chemicals and metals. The study, headed by USGS hydrologist Steve McAuley, also analyzed selected samples for chlorofluorocarbons to determine ground water age and found ages ranging from 30 year to 35 years in various topographic settings of mined areas. The median ages were the same in mined and unmined areas. These findings are the result of mixing of ground water ages in wells open to fractures at various depths, disturbance of rock from blasting, and variations in slope and terrain relief in the study area. The age of the well waters sampled also increased as distance from the mined area increased.
The USGS implemented the NAWQA Program in 1991 to support national, regional, state and local information needs and decisions related to water-quality management and policy. It is designed to answer:
- What is the condition of our nation's streams and ground water?
- How are the conditions changing over time?
- How do natural features and human activities affect the quality of streams and ground water?
- Where are those effects most pronounced?