Coal combustion residuals (CCR) are the byproducts of coal burning at power generation facilities. Also known as coal ash, CCRs primarily consist of fly ash (fine, powdery, silica material), bottom ash (coarse ash particles such as sand and rocks), and several other secondary byproducts. CCRs may contain several toxic substances associated with negative human health effects, such as mercury, arsenic, lead and low levels of polycyclic aromated hydrocarbons.
CCRs may be generated wet or dry and the composition can be changed for transportation and disposal; some wet CCRs may be dewatered for landfill disposal, while some dry CCRs may be sluiced for disposal in a surface impoundment. Millions of tons of CCRs are generated each year, producing one of the largest industrial waste streams in the United States. Approximately 40% of CCRs are recycled for beneficial uses (such as in cement and wallboard) and the remaining products are disposed of in landfills and surface impoundments.
Improperly managed CCRs can pose a risk to human health, wildlife and the environment. Poorly managed CCRs in landfills can cause groundwater contamination and fugitive dust emissions. Improper construction of CCR surface impoundments can cause catastrophic failures, which became evident in December 2008 when a CCR surface impoundment failure at the Tennessee Valley Authority (TVA) Kingston Power Plant caused the release of 5.4 million cubic yards of CCR sludge and polluted water into the environment, damaging dozens of homes, contaminating nearby rivers and covering approximately 300 acres of land.
This event prompted the US EPA to initiate the Coal Ash Surface Impoundment Integrity Assessment Program in March 2009. Over the next three (3) years, the US EPA assessed the condition and safety of all above-grade CCR surface impoundments at over 200 power plants across the nation and made the resulting information available to the public. In response to the program, power plants across the nation took action to ensure the structural stability of their CCR impoundments.
Despite the success of the Coal Ash Surface Impoundment Integrity Assessment Program, yet another coal ash disaster occurred in February 2014 when a drainage pipe collapsed beneath a CCR impoundment at the Duke Energy facility in Eden, North Carolina. The breach resulted in the release of an estimated 39,000 tons of Coal Ash into the Dan River, which eventually coated approximately 70 miles of the river with a CCR slurry plume.
Public pressures as well as the US EPA’s extensive study on the effects of coal ash on human health and the environment lead to the signing of the Disposal of Coal Combustion Residuals from Electric Utilities final rule (CCR Rule) on December 19, 2014. The final rule establishes technical requirements for the disposal of CCRs in landfills and surface impoundments under Subtitle D of the Resource Conservation and Recovery Act (RCRA). The CCR Rule was published in the Federal Register on April 17, 2015 and the effective date of the rule was on October 19, 2015.