USGS Finds Mining-Related Contamination Persists in Some Water Wells Of The Appalachian Coal Region

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) reported on Dec. 28, 2006. 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.

"Iron and manganese were commonly detected at concentrations exceeding 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 also are commonly detected in water from wells in unmined areas" said 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 said. "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 air in their homes for radon. Testing well water for iron, manganese, sulfate and bacteria also is a good idea," Kozar added.

The study compared groundwater 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 have historically had major impacts on the quality of shallow groundwater. 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 groundwater quality near bituminous coal mines is similar to groundwater quality observed in unmined areas.

As part of the USGS National Water-Quality Assessment Program (NAWQA), groundwater 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 groundwater age and found ages ranging from 30 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 groundwater 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.

The report, "Ground-Water Quality in Unmined Areas and Near Reclaimed Surface Coal Mines in the Northern and Central Appalachian Coal Regions, Pennsylvania and West Virginia," is available at http://pubs.usgs.gov/sir/2006/5059.

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