Coal plants generate large amounts of combustion waste, also called coal ash. This ash can contain varying levels of heavy metals influenced by the concentration of metal deposits within the coal itself. Metals commonly found in coal ash include arsenic, manganese, boron, chromium, and selenium. Environmental conditions such as acidity can affect the ability of metals to leach out of ash into surrounding ground and surface waters. Depending on the level of exposure, consumption of untreated ground water or fish contaminated by heavy metals can impact public health.
With the addition of Dry Sorbent Injection (DSI) technology commonly used to prevent sulfur dioxide emissions, the process could contribute up to an additional 3% to the existing ash load, depending on the sulfur content in the coal. However if a DSI system uses sodium-based sorbent, heavy metals such as arsenic can become mobile, increasing the risk of leaching and the threat to public health water systems.[i]
According to a review of EPA documents, coal ash has contaminated groundwater in three aquifers under and around the Shawnee Fossil Plant.[ii] The level of risk to public health may be considered low, however, due to utilization of public water systems installed to address previous groundwater contamination.
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[i] Sahu, R. Technical Report on Dry Sorbent Injection (DSI) and Its Applicability to TVA’s Shawnee Fossil Plant (SHF). Commissioned by the Southern Alliance for Clean Energy. April 2013.
[ii] Environmental Integrity Project. TVA’s Toxic Legacy: Groundwater Contaminated by Tennessee Valley Authority Coal Ash. November 2013. http://www.environmentalintegrity.org/news_reports/documents/20131107_tvagroundwaterreport_fulldraft_000.pdf