Frequent Questions about the Beneficial Use of Coal Ash

EPA developed frequent questions about the beneficial use of coal combustion residuals (CCR) relating to the final rule on disposal of CCR from electric utilities, implementing this final rule, and evaluation of encapsulated beneficial use of two types of CCR.

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Beneficial Use under the Final CCR Disposal Rule

  • What is beneficial use?

    Beneficial use is the recycling or reuse of coal ash in lieu of disposal. For example, coal ash is an important ingredient in the manufacture of concrete and wallboard, and EPA supports the responsible use of coal ash in this manner. This final rule supports the responsible recycling of coal ash by distinguishing beneficial use from disposal.

  • Why do companies recycle and reuse coal ash?

    Beneficial use of coal ash can produce positive environmental, economic and performance benefits such as reduced use of virgin resources, lower greenhouse gas emissions, reduced cost of coal ash disposal, and improved strength and durability of materials.

  • How is coal ash currently being beneficially used?

    As of 2012, according to the American Coal Ash Association (ACAA) data, approximately 50 percent of the CCRs beneficially used on an annual basis falls into two categories: 1) fly ash used as a direct substitute for Portland cement during the production of concrete (referred to as "fly ash concrete"); and 2) FGD gypsum used as a replacement for mined gypsum in wallboard (referred to as "FGD gypsum wallboard") during use by the consumer. Specifically, a 2012 ACAA survey indicates the largest encapsulated beneficial uses of CCRs, by more than a factor of two, are fly ash used in "concrete/concrete products/grout" (12.6 million tons) and FGD gypsum used in "gypsum panel products" (7.6 million tons).

  • How are beneficial uses of coal ash currently regulated?

    Currently, state environmental agencies are primarily responsible for regulating beneficial use. Coal ash being beneficially used is currently excluded from federal regulation under EPA's May 2000 regulatory determination that the Bevill amendment applies to such uses. Under RCRA, federal action could be taken if there were a finding of imminent or substantial endangerment in a specific circumstance.

  • Does the final rule regulate beneficial use?

    The final rule provides a definition of beneficial use to distinguish between beneficial use and disposal. This rule does not affect beneficial use applications completed before the effective date of the rule; only applications to be started after the effective date of the rule need to determine if they comply with the criteria contained in the final rule distinguishing between beneficial use and disposal.

  • Does the final rule define beneficial use of coal combustion residual?

    The final beneficial use criteria are as follows: (1) The CCR must provide a functional benefit; (2) The CCR must substitute for the use of a virgin material, conserving natural resources that would otherwise need to be obtained through practices such as extraction; (3) The use of CCRs must meet relevant product specifications, regulatory standards, or design standards when available, and when such standards are not available, CCRs are not used in excess quantities; and (4) When unencapsulated use of CCRs involves placement on the land of 12,400 tons or more in non-roadway applications, the user must demonstrate and keep records, and provide such documentation upon request, that environmental releases to ground water, surface water, soil and air are comparable to or lower than those from analogous products made without CCRs, or that environmental releases to ground water, surface water, soil and air will be at or below relevant regulatory and health-based benchmarks for human and ecological receptors during use.

  • What is structural fill?

    Structural fill is typically an earthen material used to create a strong, stable base. Structural fills are constructed by compacting earthen material to develop a structural fill that can be used to support roadways or other structures when completed. Traditionally, fill materials have been composed of soil and natural aggregates. However, coal combustion residuals can be used as a substitute for natural materials in the construction of a structural fill.

  • Does the final rule regulate structural fill?

    The final rule provides a distinction between disposal and beneficial use. In the final rule, a definition of the term "beneficial use of coal combustion residual" is provided. The definition contains four criterion that unencapsulated uses of CCRs (like structural fills) must comply with. The fourth criterion applies to any unencapsulated use of CCRs that involves placement on the land of 12,400 tons or more in non-roadway applications. If a non-roadway structural fill application, larger than 12,400 tons, complies with all four criterion, then the structural fill application is considered beneficial use. Any non-roadway structural fill application larger than 12,400 tons, that fails to comply with all of the relevant criteria in the definition of "beneficial use of CCR" will be considered disposal of CCRs subject to all of the requirements in the disposal regulation.

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Beneficial Use and Implementing the Final CCR Disposal Rule

EPA has received many questions on implementing the final CCR disposal rule. The Agency is developing responses to these questions and will be posting new ones periodically. 

These questions will cover topics including piles of CCR awaiting beneficial use, applications of CCR (such as flowable fill and agricultural uses), and the demonstration and documentation aspects of the beneficial use definition in the rule. 

General Questions

CCR Piles

  • Would a facility that stores piles of flue gas desulfurization (FGD) gypsum on the ground for ultimate beneficial use as wallboard greater than the 12,400 ton CCR rule threshold have to meet the unencapsulated use requirements?

    As EPA noted on pages 21347-21348 of the final rule, in order to be subject to RCRA, the material must be a solid waste. The statute defines a solid waste as "any garbage, refuse….and other discarded material…" 42 U.S.C. 6903 (27). As EPA noted in the proposed and final rule:

    "For some beneficial uses, CCR is a raw material used as an ingredient in a manufacturing process that have never been ''discarded,'' and thus, would not be considered solid wastes under the existing RCRA regulations. For example, synthetic gypsum is a product of the FGD process at coal-fired power plants. In this case, the utility designs and operates its air pollution control devices to produce an optimal product, including the oxidation of the FGD to produce synthetic gypsum. In this example, after its production, the utility treats FGD as a valuable input into a production process, i.e., as a product, rather than as something that is intended to be discarded. Wallboard plants are sited in close proximity to power plants for access to raw material, with a considerable investment involved. Thus, FGD gypsum used for wallboard manufacture is a product rather than a waste or discarded material. This use and similar uses of CCR that meet product specifications would not be regulated under the final rule."

    Note that whether the FGD gypsum is being managed as a "waste" or a "product" is a fact-specific determination.  Indications that the FGD gypsum is being managed as a waste or a product by the utility include the rate at which the material is being used versus being added, and whether it is being managed as a valuable product (i.e., stored or protected in the same way virgin products are managed).  For example, if more FGD gypsum is being added to a pile than can actually be used, and if the material is not being managed as a valuable product, then that would be an indication that it is it not being treated as a product; and would therefore be a "waste."

    For those materials that are "wastes," a power-generating facility that stores piles of FGD on the ground on-site at the facility for ultimate beneficial use as wallboard greater than the 12,400 ton threshold would not have to meet the unencapsulated use requirements; however, the FGD piles must be "containerized" in order to not be considered a CCR Pile (and by definition, a CCR landfill). The use of the phrase "containerized" is not intended to require that all activities occur within tanks or containment structures, but merely that specific measures have been adopted to control exposures to human health and the environment. This could include placement of the CCR on an impervious base such as asphalt, concrete, or a geomembrane; leachate and run-off collection; and walls or wind barriers (see p. 21356 of the final rule).

  • What if the facility storing the FGD on the ground is not an electric utility?

    In this case, if the facility treats the FGD gypsum as a valuable input into a production process, i.e., as a product, rather than as something that is intended to be discarded, the use would not be regulated under the final rule (see above response).

    For those materials that are "wastes," FGD gypsum that is currently being used in compliance with the definition of beneficial use, including FGD gypsum stored in a temporary pile prior to being beneficially used, would not be subject to the CCR disposal regulations.  As noted at 80 FR 21356 in the final rule preamble,

    "CCR that is currently being used beneficially—for example, fly ash that has been transferred to a cement manufacturer and that is stored off-site in a ''temporary pile,'' and that complies with all of the criteria in the definition to be considered a beneficial use including the fourth criterion relating to the placement of large quantities of unconsolidated CCR on the land— would not be subject to the regulations applicable to CCR disposal."

    Although ultimately intended for encapsulated use in wallboard, a pile of FGD gypsum that is a "waste" is still considered an unencapsulated CCR until it is actually incorporated into the wallboard; therefore, if the amount of FGD gypsum in a pile awaiting beneficial use exceeds 12,400 tons, the facility also must comply with the fourth criterion pertaining to unencapsulated non-roadway uses.  One way to ensure the fourth criterion is met is to containerize the pile; that is, adopt specific measures to control exposures to human health and the environment, such as placement of FGD gypsum on an impervious base, such as asphalt, concrete, or a geomembrane; leachate and run-off collection; and/or use of walls or wind barriers.​

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Evaluation of Two Encapsulated Beneficial Uses of CCR

  • Can fly ash be used as a replacement for portland cement in concrete and flue gas desulfurization (FGD) gypsum as a substitute for mined gypsum in wallboard?

    EPA applied the steps of the Methodology for Evaluating Encapsulated Beneficial Uses of Coal Combustion Residuals ("the Methodology") to the beneficial use of fly ash used as a replacement for portland cement in concrete and flue gas desulfurization (FGD) gypsum used as a replacement for mined gypsum in wallboard. The evaluation considered products that meet relevant physical and performance standards, that conform to standard design specifications, and that incorporate fly ash and FGD gypsum from pollution control devices currently used in the United States. Based on the findings of the evaluation, the Agency concluded that fly ash concrete and FGD gypsum wallboard are both appropriate beneficial uses. Thus, the Agency continues to support the beneficial use of fly ash in concrete and FGD gypsum in wallboard.

  • What is "encapsulated beneficial use" of coal combustion residuals (CCR)?

    The Agency has defined "beneficial use" as the reuse of CCRs in a product that provides a functional benefit; that replaces a product made from virgin raw materials on the market, thus conserving natural resources that would otherwise need to be obtained through practices, such as extraction; and that meets relevant product specifications and regulatory standards. An encapsulated beneficial use is one that binds the CCRs into a solid matrix that minimizes their mobilization into the surrounding environment. Examples of encapsulated uses include, but are not limited to:

    • Filler or lightweight aggregate in concrete
    • A replacement for, or raw material used in production of, cementitious components in concrete or bricks
    • Filler in plastics, rubber, and similar products
    • Raw material in wallboard production
    • Will EPA evaluate other encapsulated beneficial uses? If not, who is responsible for conducting evaluations of other encapsulated CCR beneficial uses? What is EPA's role in evaluating these beneficial uses?

      EPA has no plans to evaluate other encapsulated beneficial uses of CCRs. However, the Methodology is being made available so that federal or state authorities, beneficial users, and other interested parties can, if they choose, use the methodology to evaluate other encapsulated beneficial uses of CCRs. Use of this methodology is voluntary, not regulatory, and is not a replacement for existing regulatory requirements. Many states have beneficial use programs, and they should be consulted to determine whether a specific CCR beneficial use is allowed. Other parties who use the Methodology should consult with their state to determine whether the application of the methodology is consistent with all applicable state requirements. EPA has no role in reviewing or approving evaluations conducted by others, but can assist with any questions about how to properly apply the methodology.

    • How does EPA's encapsulated beneficial use methodology work?

      The Methodology is composed of five steps. The party conducting the evaluation does not need to follow these steps in the order that they are outlined in the Methodology or necessarily use all of the steps. They can begin the evaluation at any step, can apply the individual steps in an order that makes best use of the available data, and can stop the evaluation at any step when they determine that the beneficial use product will not release constituents of potential concern (COPC) greater than releases found in analogous products (i.e., products without CCRs) or if there is no exposure pathway in which a person or ecological organism may come into contact with the COPC. The methodology's five steps are:

      Step 1: (Literature Review and Data Collection): This step involves the collection and review of available literature on a CCR and its beneficial use. The purpose of this step is twofold: 1) to establish whether existing evaluations are sufficient to demonstrate that releases from the CCR beneficial use are comparable to or lower than those from an analogous product, or are at or below relevant regulatory and health-based benchmarks, and 2) to collect data on any COPCs that may be present in and released from the CCR beneficial use product, but were not sufficiently addressed by existing evaluations. If existing evaluations have already sufficiently addressed all potential releases, then no further evaluation is warranted and the beneficial use of the product is appropriate.

      Step 2: (Comparison of Available Data): This step involves a comparison of the COPC releases from the CCR beneficial use product with those from an analogous product that it replaces. The purpose of this step is to determine whether there is the potential for higher COPC releases from the beneficial use product than from the analogous product. If releases of all COPCs are found to be comparable to or lower than those from the analogous product, then no further evaluation is warranted and the beneficial use of the product is appropriate.

      Step 3: (Exposure Review): The purpose of this step is to identify the ways that different receptors may be exposed to the remaining COPCs. This information is then summarized through a conceptual model. Any COPC releases that do not have a complete exposure pathway are eliminated from further consideration and, if none of the COPCs have a complete exposure pathway, then no further evaluation is warranted and the beneficial use of the product is appropriate.

      Step 4: (Screening Assessment): ;This step uses a combination of conservative (i.e., likely to overestimate exposures) environmental, fate and transport, and/or exposure data to estimate potential COPC exposures. These conservative exposures are then compared to relevant screening benchmarks. If all exposures are below these screening benchmarks, then no further evaluation is warranted and the beneficial use of the product is appropriate.

      Step 5: (Risk Assessment): This step uses environmental, fate and transport, and/or exposure data that are more representative of real world conditions to estimate potential COPC exposures. These more realistic exposures are then compared to relevant risk benchmarks. If all exposures are below these risk benchmarks, then no further evaluation is warranted and the beneficial use of the product is appropriate.

    • What coal combustion residual (CCR) uses did EPA evaluate in the Application document and how was the methodology applied?

      EPA applied the methodology to the two largest CCR uses - coal fly ash concrete and FGD gypsum wallboard. Below is a summary of the evaluation made in each step of the Methodology as described in Question 4:

      Step 1: The following types of releases that may occur during use of fly ash concrete and FGD gypsum wallboard were identified: 1) generation of dust, 2) leaching to ground and surface water, 3) emissions to air, and 4) decay of naturally occurring radionuclides.

      • From a literature review, a number of existing studies were found to be of sufficient applicability and quality to rely upon to draw the following conclusions:
      • For both fly ash concrete and FGD gypsum wallboard, the findings from the cumulative body of evidence from existing studies were used to eliminate radioactive decay from further consideration.
      • For FGD gypsum wallboard, the findings from the cumulative body of evidence from existing studies were used to eliminate all releases from further consideration, except for emissions to air.
      • For fly ash concrete, the findings from the cumulative body of evidence from existing studies were used to identify COPCs that had not been sufficiently addressed for particular releases: 23 COPCs for generation of dust, nine COPCs for leaching to ground and surface water, and one COPC for emissions to air.
      • For more information, see Table 1-2: List of COPCs Remaining Following Step 1 in the Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard

      Step 2: All of the data identified in Step 1 was aggregated to allow a comparison of releases from CCR fly ash concrete and FGD gypsum wallboard to releases from their respective non-CCR analogous products (i.e., portland cement concrete and mined gypsum wallboard) during use. The evaluation found that concentrations of 2 COPCs in dust from fly ash concrete were comparable to or lower than those in dust from portland cement concrete. The evaluation also found that concentrations of 5 COPCs in leachate from fly ash concrete and portland cement concrete were comparable. Therefore, the evaluation did not carry these COPCs forward for further consideration, but retained all other COPCs from fly ash concrete and FGD gypsum wallboard for further consideration. For more information, see Table 2-4: List of COPCs Remaining Following Step 2 in the Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard

      Step 3: No releases or associated COPCs were eliminated at this step. For more information, see Table 3-1: List of COPCs Remaining Following Step 3 in the Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard

      Step 4: The evaluation conservatively estimated COPC exposures that may occur during use of fly ash concrete and FGD gypsum wallboard, and compared these exposures to relevant regulatory or health-based screening benchmarks. The evaluation found that the remaining 21 COPCs for generation of dust, 4 COPCs for leaching to ground and surface water, and 1 COPC for emissions to air were below all relevant screening benchmarks and the beneficial uses of these products are appropriate. Therefore, the evaluation did not proceed to Step 5. EPA's evaluation concluded that the beneficial use of encapsulated CCRs in concrete and wallboard is appropriate because they are comparable to virgin materials or below the agency's health and environmental benchmarks.

    • Will EPA be evaluating "unencapsulated beneficial uses" of coal combustion residuals (CCRs)?

      In developing a framework to evaluate the potential risks associated with unencapsulated uses of industrial non-hazardous secondary materials (secondary materials), including CCR, the Agency determined that the principles outlined in the 2013 Methodology for Evaluating Encapsulated Beneficial Uses of Coal Combustion Residuals are also applicable and relevant to unencapsulated uses. EPA combined the discussion of encapsulated and unencapsulated uses into a single document and renamed it the Methodology for Evaluating the Beneficial Use of Industrial Non-Hazardous Secondary Materials (BU Methodology) to reflect the broader scope.

      EPA's BU Methodology may be used to evaluate the potential for impacts to human health and the environment for both encapsulated and unencapsulated uses of secondary materials, including unencapsulated CCR uses. EPA is making the BU Methodology available to assist others with the design and review of beneficial use evaluations. EPA currently has an evaluation underway, in collaboration with the U.S. Department of Agriculture, assessing the use of flue gas desulfurization gypsum as an agricultural amendment. Once this evaluation is completed, EPA has no further plans to evaluate additional beneficial uses of secondary materials.

    • What types of literature sources did the Agency rely upon in this application of the Methodology?

      This evaluation used studies and data pertaining to either beneficial use products or their raw materials. In most cases, the literature sources were drawn from peer reviewed journals. An assessment determined whether data sources were relevant, sufficiently explained the data and assumptions relied upon, accounted for sources of uncertainty and variability, and had undergone an independent review in some form. Some data were submitted directly to EPA by generators, regulatory entities, and other interested parties. These data have been made available for comment to both the public and a panel of independent peer reviewers through the 2010 Human and Ecological Risk Assessment of Coal Combustion Wastes.

    • Does EPA require the use of data from certain test methods when applying the Methodology?

      EPA's encapsulated beneficial use Methodology does not require any specific test methods, only that the data generated is of sufficient quality to support the final conclusions of the evaluation.

    • Can EPA's encapsulated beneficial use methodology be used to determine if a specific encapsulated use of coal combustion residuals (CCR) is "safe"?

      The Agency developed this methodology to evaluate the potential impacts to human health and the environment that may result from the encapsulated beneficial uses of CCRs. This methodology may be used to show whether releases of constituents of potential concern, such as metals from encapsulated beneficial uses, are comparable to or lower than those from analogous non-CCR products, or are at or below relevant regulatory and health-based benchmarks for human and ecological receptors.

    • Can EPA's encapsulated beneficial use methodology be used to determine if the "unencapsulated" beneficial reuse of coal combustion residuals (CCR) is safe?

      This methodology is not intended to be applied to unencapsulated beneficial uses of CCRs. EPA developed the Methodology for Evaluating the Beneficial Use of Industrial Secondary Materials (BU Methodology), which can be used to evaluate the potential impacts to human health and the environment for both encapsulated and unencapsulated uses of industrial non-hazardous secondary materials, including unencapsulated CCR uses.

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