Human and Ecological Risk Assessment - Earthjustice

Section 1.0Introduction1.0 Introduction1.1 BackgroundThe U.S. Environmental Protection Agency (EPA) has evaluated the human health andenvironmental risks associated with coal combustion waste (CCW) management practices,including disposal in landfills and surface impoundments. In May 2000, EPA determined thatregulation as hazardous wastes under Subtitle C of the Resource Conservation and Recovery Act(RCRA) was not warranted for certain CCWs, but that regulation as nonhazardous wastes underRCRA Subtitle D was appropriate. However, EPA did not specify regulatory options at that time.This risk assessment was designed and implemented to help EPA identify and quantify humanhealth and ecological risks that may be associated with current management practices for highvolumeCCWs. These wastes are fly ash, bottom ash, boiler slag, and flue gas desulfurization(FGD) sludge, along with wastes from fluidized-bed combustion (FBC) units and CCWscodisposed with coal refuse. This risk assessment will help EPA develop CCW managementoptions for these high-volume waste streams. Details on EPA’s CCW work can be found athttp://www.epa.gov/epawaste/nonhaz/industrial/special/fossil/index.htm.Note that the full-scale risk assessment described in this report was primarily conductedin 2003, meaning that the data collection efforts to support the risk assessment were based on thebest information available to EPA at that time. As a result, more recent Agency efforts tocharacterize CCW wastes and management practices, such as the joint EPA and U.S. Departmentof Energy (DOE) survey of CCW waste management units (WMUs) (U.S. DOE, 2006) andEPA’s recent study of CCW chemistries and leaching behavior (U.S. EPA, 2006c, 2008c), werenot considered in the main analysis phase of this risk assessment. However, these more recentefforts are discussed as part of the risk characterization, and EPA is currently evaluating how tobest incorporate and consider the results and findings of these studies in future efforts to addressCCW management practices.The Agency has revised this risk analysis document to address comments on theanalytical methodology, data, and assumptions used in the risk assessment from an independentscientific peer review by experts outside EPA. Public comments (available in docket numberEPA-HQ-RCRA-2006-0796 1 ) were made available to the peer reviewers for their considerationduring the review process. The peer review focused on technical aspects of the analysis,including the construction and implementation of the Monte Carlo analysis, the selection ofmodels to estimate the release of constituents found in CCW from landfills and surfaceimpoundments and their subsequent fate and transport in the environment, and thecharacterization of risks resulting from potential exposures to human and ecological receptors.EPA’s responses to the peer-review comments, including descriptions of the revisionsincorporated in this document to address those comments, are available in a separate response-tocommentsdocument (U.S. EPA, 2009d).1 Available at http://www.regulations.gov.April 2010–Draft EPA document. 1-1