Water Quality Impacts of Coal Combustion Waste Disposal in Two West Virginia Coal Mines
This report documents very high selenium and thallium in surface waters, and high levels of selenium and arsenic in groundwaters downstream from the Stacks Run Refuse Site and Albright Site, respectively, two West Virginia coal combustion waste disposal areas in surface mines.
Burning coal creates several kinds of waste, depending on the processes used. Some of these wastes include bottom ash, fly ash, flue-gas desulfurization byproducts, and fluidized bed combustion (FBC) ash, an alkaline ash disposed of extensively in West Virginia coal mines.
These coal combustion wastes (CCWs) are currently landfilled, slurried to surface impoundments, disposed in mines, or sometimes reused in construction materials. In general, disposal is costly, increasing the price of coal energy for consumers and decreasing the profits for producers. But because these materials contain certain toxic compounds, failure to dispose of them with due vigilance would be costly in terms of environmental health.
Some proponents of disposal in former coal mines suggest that returning alkaline CCWs to mines is beneficial and need not undergo careful, long-term water quality monitoring. Others suggest that CCWs introduce toxic metals into the environment and that, despite infrequent monitoring, these metals are detected downstream from disposal sites.
The National Academy of Sciences convened a committee within the National Research Council in 2004 to investigate this issue. The prospectus of that committee lists a number of points to be addressed, shown in Table 1. This report seeks to provide input into the points highlighted in bold.
Coal ash has been disposed on 88 coal mining sites across West Virginia. Almost two-thirds of these sites are located in Preston and Monongalia Counties, two adjacent counties in the north-central part of the state (WVDEP, 2004a). This report summarizes the water quality impacts of CCW disposal in two former mines in Preston County (Figure 1). The first location, the Stacks Run Refuse Site Extension, received up to 2.2 million tons of CCW. Up to 4 million tons have been placed at the Albright site.
Preston County was mined widely through approximately 1990. The most common coal mined was from the Upper Freeport seam, which contains high levels of sulfur. Many of the county’s streams are impaired by acid mine drainage (AMD). There is a very clear correlation between impaired streams (identified using benthic macroinvertebrate community metrics) and the original location of mineable, Upper-Freeport coal (Mains et al., 1997). Both study areas were former coal mines where the acid-forming Upper Freeport as well as other types of coal were mined, stored, or processed. Both sites are surrounded by surface waters that are impaired by AMD. And at both sites, FBC ash was applied.
FBC is an alkaline, calcium-rich material produced when coal is burned in the presence of lime. It has been used extensively as an amendment for the refuse coal at both these sites, and at many other sites as well. It is often believed that the high pH values associated with this material prevent dissolution of many toxic chemicals found in the ash. Because the FBC process reduces emissions of sulfur dioxide, however, the process is usually used to burn coal with larger concentrations of impurities.
Very high levels of several toxic metals are observed in surface and groundwater downgradient from CCW disposal sites. Toxic concentrations of these metals often occur at times when pH effects from FBC ash are observed, and may require several years before they appear in water. Ash disposal at mine sites does not appear to keep metals out of nearby waters.
To protect waters, monitoring must continue for many years. In the data examined in this report, high concentrations of selenium and thallium were found at the Stacks Run Refuse Site Extension almost a decade following the beginning of mine disposal of CCW.
Even though they were sufficient to identify several exceedances of toxic metal concentrations, the practices used now by WVDEP are insufficient. More stringent practices are required to properly monitor the disposal of CCWs in mines so that regulators actually review and use these data to ensure that water resources are protected. Enforceable regulations, rather than unenforceable policies now used, should be considered.