Human and Ecological Risk Assessment - Earthjustice

Executive SummaryHuman and Ecological Risk Assessment of Coal Combustion Wastesassessment uncertainties is presented inSection 4.4 of the report.ConclusionsGiven the results and characterizationabove, composite liners, as modeled in thisrisk assessment, effectively reduced risksfrom all pathways and constituents belowthe risk criteria for both landfills and surfaceimpoundments. The CCW risk assessmentsuggests that the management of CCW inunlined landfills and unlined surfaceimpoundments may present risks to humanhealth and the environment. Selenium incertain types of WMUs managing certaintypes of CCW may present a risk of clinicalselenosis to highly exposed groundwaterusers or fish consumers, or a risk of adverseeffects to highly exposed aquatic receptors.Arsenic in certain types of WMUs managingcertain types of CCW may present lifetimecancer risks above EPA’s range of concernto highly exposed groundwater users.Estimated risks from clay-lined units arelower than the risks of unlined units, but arestill above the risk criteria used for thisanalysis. In addition, surface impoundmentstypically showed higher risks than landfills,regardless of liner type. Finally, for surfaceimpoundments, codisposal of CCW withcoal refuse results in significantly higherrisks from arsenic and certain otherconstituents than CCW disposed alone,while for other constituents, managingCCWs alone results in higher estimated risksthan codisposed CCW.These risk results are in many casesconsistent with damage cases compiled byEPA (U.S. EPA, 2000, 2003e, 2007) andothers (Lang and Schlictmann, 2004;Zillmer and Fauble, 2004; Carlson andAdriano, 1993; Rowe et al., 2002; Hopkinset al., 2006). 7 For example, the full-scalemodeling of selenium released from unlinedsurface impoundments into groundwatersuggests that certain fish consumers may beexposed to relatively high levels ofselenium, consistent with fish consumptionadvisories at some of the proven damagecase sites. These results suggest that with ahigher prevalence of composite liners in newCCW disposal facilities, along withpractices to prevent codisposal of coal refusewith CCW, future national risks from onsiteCCW disposal are likely to be lower thanthose presented in this risk assessment(which is based on 1995 CCW WMUs).ReferencesCarlson, C.L., and D.C. Adriano. 1993.Environmental impacts of coal combustionresidues. J. Environ. Qual. 22(227-247).Hopkins, W.A., S.E. DuRant, B.P. Staub,C.L. Rowe, and B.P. Jackson. 2006.Reproduction, embryonic development,and maternal transfer of contaminants inthe amphibian Gastrophryne carolinensis.Environmental Health Perspectives114(5):661–666.Lang, D.J., and J.R. Schlictmann. 2004.Leaching of arsenic from a fly ash dumpin Beverly, Massachu-setts. InProceedings of State Regulation of CoalCombustion By-Product Placement atMine Sites. May 4–6, 2004, Harrisburg,Pennsylvania. U.S. Department of theInterior, Office of Surface Mining, Alton,IL. Available at http://www.mcrcc.osmre.gov/MCR/Resources/ccb/PDF/State_Regulation_of_CCB_Placement.pdf.Rowe, C.L., W.A. Hopkins, and J.D.Congdon. 2002. Ecotoxicological7 See Sections 4.1.5 and 4.2.5 for a more completediscussion of CCW damage cases and riskassessment results.April 2010–Draft EPA document.ES-10