Coal Ash Reuse
Coal ash, also referred to as coal combustion residuals (CCR), can be used in different products and materials. Coal ash can be beneficially used to replace virgin materials removed from the earth, thus conserving natural resources. EPA encourages the beneficial use of coal ash in an appropriate and protective manner, because this practice can produce positive environmental, economic, and product 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.
While the beneficial use of coal ash has these potential benefits, the environmental impacts associated with their use should also be considered. The most recent available data from responses to an American Coal Ash Association (ACAA) survey of electric utilities shows that in 2018, at least 41 million tons of coal ash were beneficially used.
On this page:
- How is the Beneficial Use of Coal Ash Currently Regulated?
- Encapsulated Beneficial Use
- Unencapsulated Beneficial Use
How is the Beneficial Use of Coal Ash Currently Regulated?
Currently, state environmental agencies are primarily responsible for regulating beneficial use. Beneficial use of coal combustion residuals is currently excluded from federal regulation under EPA's May 2000 regulatory determination that the Bevill amendment applies to such uses. Under the Resource Conservation and Recovery Act, federal action could be taken if there were a finding of imminent or substantial endangerment in a specific circumstance.
The April 2015 final CCR disposal rule reaffirms EPA's Bevill determination for beneficial use, and provides a definition to distinguish between beneficial use and disposal. The beneficial use of CCR definition is comprised of four criteria:
- the CCR must provide a functional benefit;
- the CCR must substitute for the use of a virgin material;
- meets product specifications and/or design standards; and
- when unencapsulated use of CCR involves placement on the land of 12,400 tons or more in non-roadway applications, the user must demonstrate and provide 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 CCR, or that releases will be below relevant regulatory and health-based benchmarks for human and ecological receptors.
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.
Encapsulated Beneficial Use
Encapsulated uses of CCR involve binding the coal ash, such as in wallboard, concrete, roofing materials, and bricks in a way that minimizes the CCR from escaping into the surrounding environment. There are important benefits to the environment and the economy from the use of coal ash in encapsulated form. The two largest encapsulated uses reported by the ACAA in 2018 are fly ash used in "concrete/concrete products/grout" (13.4 million tons) and flue gas desulfurization (FGD) material gypsum used in "gypsum panel products" (12.3 million tons), making up over 60 percent of the total amount of coal ash beneficially used.
In 2013, EPA developed a methodology for evaluating encapsulated beneficial uses of CCR. This methodology can support beneficial use determinations by allowing the user to demonstrate whether releases from an encapsulated beneficial use of coal ash are comparable to or lower than those from analogous products made without coal ash, or are at or below relevant regulatory and health-based benchmarks, during use.
EPA used the methodology to evaluate the potential environmental impacts associated from fly ash used as a direct substitute for portland cement in concrete, and from FGD gypsum used as a replacement for mined gypsum in wallboard. EPA’s evaluation concluded that the beneficial use of encapsulated CCR in concrete and wallboard is appropriate because environmental releases are comparable to or lower than those from analogous non-CCR products or are at or below relevant regulatory and health-based benchmarks.
Unencapsulated Beneficial Use
Unencapsulated uses of coal ash are those where coal ash is used in a loose particulate, sludge or other unbound form. In 2018, ACAA reported about 20 percent of CCR (8.1 million tons) are beneficially used in unencapsulated uses. The largest unencapsulated use is CCR used in “structural fills/embankments” (4.6 million tons).
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. So, EPA combined the discussion of encapsulated and unencapsulated uses into a single document and renamed it the Methodology for Evaluating Beneficial Uses of Industrial Non-Hazardous Secondary Materials (BU Methodology) to reflect the broader scope. EPA’s BU Methodology may be used to evaluate both encapsulated and unencapsulated uses of a wide range of secondary materials, including CCR.