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- CCR Constituent Database: This database contains all of the data collected in support of evaluations of CCRs since the Agency’s 1988 Report to Congress (US EPA, 1988). The database contains information on the identity and concentrations of constituents that may be present in CCRs. The Agency’s most recent evaluation of CCR disposal practices provides an overview of historical data collection efforts prior to the finalization of the 2010 CCR Risk Assessment (US EPA, 2010a). However, since the completion of this risk assessment, EPA has incorporated new data into the database as it has become available.
- Eckert and Guo (1998): Heavy Metals in Cement and Cement Kiln Dust from Kilns Co-Fired with Hazardous Waste-Derived Fuel: Application of EPA Leaching and Acid-Digestion Procedures. This literature source contains data on COPC concentrations in portland cement.
- Garrabrants et al. (2013): Effects of Coal Fly Ash Use in Concrete on Mass Transport-Based Leaching of Potential Concern. This literature source contains data on COPC leaching rates using EPA Leaching Environmental Assessment Framework (LEAF) Method 1315 from concretes made with fly ash and portland cement.
- Golightly et al. (2005): Gaseous Mercury from Curing Concretes that Contain Fly Ash:
Laboratory Measurements. This literature source contains data on mercury concentrations in fly ash, as well as mercury emanation rates from fly ash and portland cement concretes.
- Golightly et al. (2009): Fly Ash Properties and Mercury Sorbent Affect Mercury Release from Curing Concrete. This literature source contains data on mercury concentrations in fly ash and portland cement, as well as mercury emanation rates from concretes made with fly ash and portland cement.
- Kosson et al. (2013): pH-dependent Leaching of Constituents of Potential Concern from Concrete Materials Containing Coal Combustion Fly Ash. This literature source contains data on COPCs using EPA LEAF Method 1313 from concrete made with fly ash and portland cement.
- Pflughoeft-Hassett et al. (1993): Comparative Leaching of Midwestern Coal Fly Ash and Cement. This literature source contains data on COPC concentrations in portland cement.
- Portland Cement Association (PCA) (1992): An Analysis of Selected Trace Metals in Cement and Kiln Dust. This literature source contains data on COPC concentrations in portland cement.
The current evaluation considered several other potentially relevant literature sources that contain data on leaching from fly ash concrete, but did not rely upon those sources in this beneficial use evaluation because more appropriate data were available. These include: Zhang et al., 1985; Rankers and Hohberg, 1991; Kanare and West, 1993; Church et al., 1995; UKDETR, 1998; Meji et al., 2001;
Zhang et al. 2001; McCann et al., 2007; and Giergiczny and Krol, 2008. These studies provide leachate data collected with single pH leach tests. Examples of single pH leach tests include the Deionized Water Leaching Test (ASTM D3987-85), the Synthetic Precipitation Leaching Procedure (SPLP), and the Toxicity Characteristic Leaching Procedure (TCLP). These single pH data do not reflect the timedependent release of COPCs from intact concrete. In addition, the current evaluation did not incorporate the leachate data from US EPA (2012b) because the majority of these samples are from fly ash mortars.
The higher porosity of mortars can result in leaching that is not considered representative of fly ash concrete.
1.1.3 Summary of Releases Identified for Fly Ash Concrete Based on the review of the available literature, the current evaluation initially identified four potential releases from fly ash concrete that may occur during use: 1) generation of dust, 2) emanation to air, 3) leaching to ground and surface water, and 4) decay of naturally occurring radionuclides. A review of existing evaluations found them to be of sufficient quality and applicability to eliminate decay of
1-9 1.2 FGD Gypsum Wallboard 1.2.1 Existing Evaluations for FGD Gypsum Wallboard The current beneficial use evaluation reviewed all existing evaluations identified in the available literature according to the recommendations of Summary of General Assessment Factors for Evaluating the Quality of Scientific and Technical Information (US EPA, 2003a). 7 The focus of this review was to determine whether these existing evaluations could form the basis for defensible conclusions regarding FGD gypsum wallboard. The review determined whether the existing evaluations pertained to FGD gypsum wallboard, clearly and sufficiently explained the data and assumptions relied upon, accounted for major sources of uncertainty and variability, and had undergone an independent review in some form. The remainder of this subsection summarizes the existing evaluations used to identify releases and associated COPCs for further consideration. Under the title of each evaluation, a brief summary of relevant findings is provided. Where multiple existing evaluations were pertinent to a given topic, all the summaries are combined under a list of the evaluation titles. Many of the existing evaluations are the same as presented in Section 1.1, but with a focus on FGD gypsum wallboard.
US EPA (1998): Supplemental Report to Congress on Remaining Wastes from Fossil Fuel Combustion Technical Background Document: Beneficial Use of Fossil Fuel Combustion Wastes This report identified the following types of releases to the surrounding environment that may occur from CCR products: 1) generation of dust, 2) emanation to air, 3) leaching to ground and surface water, and 4) decay of naturally occurring radionuclides. Because this report addresses the beneficial use of CCRs, it is directly applicable to the current evaluation of FGD gypsum wallboard. Therefore, each identified type of release was retained for further consideration.
US EPA (1999): Report to Congress: Wastes from the Combustion of Fossil Fuels: Volume 2 Methods, Findings, and Recommendations This report reviewed all of the data available to the Agency at the time of publication on releases from CCRs generated in the United States. The data indicated that all concentrations of organic constituents, such as polyaromatic hydrocarbons and dioxins, were near or below analytical detection limits both in CCRs and in leachate released from CCRs. Based on these data, the report concluded that organic constituents are not COPCs associated with CCRs. Consideration of updated toxicity values does not alter the conclusions of this report. Furthermore, no additional data have been identified since the completion of this report that would indicate the potential for higher organic levels. These organic constituents are not volatile under standard environmental conditions (e.g., temperature and atmospheric pressure), making a release of these complex organic compounds from FGD gypsum wallboard at rates higher than those from pure FGD gypsum unlikely. Therefore, the current evaluation eliminated organic constituents from further consideration.
EPA developed this document in response to guidelines issued by OMB (US OMB, 2002) under section 515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001 (Public Law 106-554; H.R. 5658).
Consumer Product Safety Commission (CPSC) (2010a): Final Report on an Indoor Environmental Quality Assessment of Residences Containing Chinese Drywall CPSC (2010b): Staff Preliminary Evaluation of Drywall Chamber Test Results: Reactive Sulfur Gases The CPSC commissioned a series of evaluations in response to concerns raised by the public over the potential for imported Chinese wallboard to cause adverse health effects. In one evaluation, air samples were collected at 41 homes that had reported problematic wallboard and 10 homes that had reported no issues (CPSC, 2010a). The evaluation found houses with problem wallboards had higher indoor air concentrations of select volatile organic compounds (e.g., n-hexane) and volatile sulfur compounds (e.g., hydrogen sulfide and carbon disulfide). 8 However, these higher levels were generally below associated EPA health benchmarks. In a subsequent study, differences in the emanation rates of volatile sulfur gases from domestic and imported wallboards were evaluated in a laboratory setting (CPSC, 2010b). The preliminary results found considerably lower emanation rates of volatile sulfur gases from all domestic wallboards compared to the problematic imported wallboards. CPSC (2010b) did not specify whether any of the domestic wallboards evaluated were made with FGD gypsum. However, CPSC (2010a) specifically compared the characteristics of domestic mined and FGD gypsum wallboards. This evaluation found that the indicators of high volatile sulfur releases associated with the problematic imported wallboard were absent from all FGD gypsum wallboard samples. Based on these findings, the current evaluation eliminated these releases from further consideration.
Long et al. (2012): Potential Indoor Air Exposures and Health Risks from Mercury Off-Gassing of Coal Combustion Products Used in Building Materials Long et al. (2012) measured the rate at which wallboard made with and without FGD gypsum emits mercury vapor and used these measurements to calculate resulting indoor air concentrations in a home and a school. The report then compared these concentrations to available health-based benchmarks. This evaluation concluded that potential indoor air concentrations were below levels of concern. Because this evaluation specifically addressed releases from FGD gypsum wallboard, the results are directly applicable to the current evaluation. However, the relatively small number of FGD gypsum samples evaluated introduces uncertainty as to whether the mercury emanation rates measured adequately characterize the range of potential emanation rates from fly ash concrete.
Therefore, the current evaluation retained mercury as a COPC for emanation to air.
The evaluation focused on organics, such as n-hexane and formaldehyde, which are associated with adhesives and additives added to wallboard during production, rather than with FGD gypsum.
1-11 Wollenburg and Smith (1962): Portland Cement for a Low-Counting Facility Lindeken and Coles (1977): The Radium-226 Content of Agricultural Gypsums Zikovsky and Kennedy (1992): Radioactivity of Building Materials Available in Canada Henkels and Gaynor (1996): Characterizing Synthetic Gypsum for Wallboard Manufacture Roper et al (2013): Analysis of Naturally-Occurring Radionuclides in Coal Combustion Fly Ash, Gypsum, and Scrubber Residue Samples A number of existing evaluations were identified that address radiation from FGD gypsum and FGD gypsum wallboard from a broad range of domestic and international sources. Although some of these evaluations do not directly address FGD gypsum wallboard, the results are applicable to the current evaluation because the beneficial use of FGD gypsum in wallboard is unlikely to appreciably alter radionuclide concentrations in the raw material. These evaluations include peer-reviewed publications, guidance documents, and voluntary standards that have been developed and reviewed by experts in the field of radiation and health physics. This body of work extends back nearly forty years, and has already been well summarized through the literature reviews contained in more recent existing evaluations. Therefore, only these key recent evaluations, which form the basis for the conclusions in this beneficial use evaluation, are summarized in the following text.
A number of national and international organizations develop and maintain guidance for managing public exposures to everyday sources of radiation, such as building materials. Evaluations of radiation exposure are often based on the recommendations of these guidances. The relevant organizations are discussed in Section 1.1.1.
- Roper et al. (2013) measured the activity of radionuclides in the uranium and thorium decay series, as well as potassium-40, from samples of FGD gypsum collected across the United States.
The study found that FGD gypsum activities fell within the range of activities previously reported from extensive sampling of European mined gypsum. Consideration of additional activity data reported in the literature for North American mined gypsum and wallboard does not result in different conclusions (Wollenberg and Smith, 1962; Lindeken and Coles, 1977; Zikovsky and Kennedy; 1992).
The existing evaluations identified demonstrate that the potential exposures to gamma radiation from FGD gypsum wallboard are comparable to those from mined gypsum wallboard. No existing evaluations were identified that evaluated radon emanation from FGD or mined gypsum. However, because the radionuclide concentrations in raw FGD and mined gypsum are comparable; the physical structures of the finished products are nearly identical (Henkels and Gaynor, 1996); and the finished products are used in the same way, this evaluation concludes that the rate of radon emanation also will be comparable. Therefore, the current evaluation eliminated radionuclides from further consideration.
1.2.2 Data Collection for FGD Gypsum Wallboard The review of existing evaluations discussed in Section 1.2.1 identified one potential release and a single associated COPC that the existing evaluations had not sufficiently addressed. Therefore, the current evaluation assembled data on this remaining release and the associated COPC from the existing 1-12 evaluations and other available literature. These data form the basis for the evaluation of COPC releases from FGD gypsum wallboard conducted in subsequent steps of this evaluation. The remainder of this section enumerates the major sources from which these data were drawn. Appendix A provides a further discussion of each data source, along with a presentation of the corresponding raw data.
- Electric Power Research Institute (2010): Public Comments to Hazardous and Solid Waste Management System; Identification and Listing of Special Wastes; Disposal of Coal Combustion Residuals from Electric Utilities. This literature source contains data on mercury concentrations in FGD gypsum and mined gypsum.
- Gypsum Association (2010): Public Comments to Hazardous and Solid Waste Management System; Identification and Listing of Special Wastes; Disposal of Coal Combustion Residuals from Electric Utilities. This literature source contains data on mercury concentrations in FGD gypsum and mined gypsum.