Below is a list of frequently asked questions. Click each dropdown to view the answers.

Getting Started

A structural fill is an engineered fill designed to improve land for an intended end use. Typically the land is unusable for the intended use unless fill material is imported to raise the elevation to the desired design elevations. Coal ash is a useful fill material due to its homogenous particle size, predictable geotechnical characteristics, low unit weight, relatively high shear strength and ease of handing and compaction. Charah Solutions utilizes coal ash and places and compacts it in accordance with approved ASTM design criteria.

As used in reference to structural fills, “lined” or “fully lined” refers to the protective measures employed in the design to prevent or limit water from penetrating or passing through the actual fill material. The liner can be a layer of low permeability soil and/or manufactured synthetic material. As implemented by Charah Solutions, in a fully lined structural fill, the ash is placed between a series of liners, with the top and bottom ultra-low permeability synthetic liners being heat-welded together to encapsulate and isolate the ash. The completed fully lined structural fill is then covered by soil to accommodate the final surface needs for the design purpose. Fully lined structural fills are designed to meet all ASTM, state and federal standards including strict groundwater monitoring and reporting. Charah Solutions uses the best practices, materials and technology for structural fills. Charah Solutions is currently nearing completion of a coal ash structural fill project at Asheville (North Carolina) Regional Airport. Click here to learn more about the construction process and components of a fully lined structural fill.

Concrete producers demand the quality and availability that fly ash brings to every project, with all the advantages of added strength, durability, increased workability and improved finish product quality.

The main chemical components of fly ash are silica, alumina, iron and calcium oxides; all identical constituents of Portland cement. These common components contribute to added strength and durability of concrete.

Charah Solutions has the expertise to evaluate ash sources and determine if they qualify for use in a variety of applications. With our experience, Charah Solutions will determine if your bottom ash is a candidate for utilization. Charah Solutions has a successful track record of finding markets for beneficially using bottom ash.


EPA published the Coal Combustion Residuals (CCR) Regulations in the Federal Register on April 17, 2015. The new requirements will regulate CCRs as non-hazardous materials under Subtitle D. The regulations establish national criteria under which States can govern CCRs in a manner similar to municipal solid wastes. The regulations address CCR disposal from utility boilers that burn greater than 51% coal fuels and they exempt beneficial use of CCRs. The new regulations define “beneficial use” and provide a mechanism where structural fills can demonstrate that they meet the definition as “beneficial use.”

The CCR Regulations became effective 180 days from publication and place requirements on electric utilities that operate coal plants to review existing sites and implement new operational requirements to comply with this broad reaching program. The Federal Register rules are located at http://www.gpo.gov/fdsys/pkg/FR-2015-04-17/pdf/2015-00257.pdf.

Related to CCR disposal, the new criteria established measures that ensure groundwater monitoring at all active CCR disposal units and requires implementation of measures to ensure that CCRs are properly disposed of in units that are protective of human health and the environment. Design criteria and location restrictions are established for any new disposal unit.

By establishing the new criteria, EPA has once again confirmed that coal ash is not hazardous and can be adequately managed under a non-hazardous regulatory approach. This finding is supported by many years of research by the scientific community and states that currently manage solid wastes of all types. In addition to the CCR regulations, EPA has also released its report on the beneficial use of fly ash in concrete and gypsum in wallboard. The study titled “Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard” confirms that use of ash and coal combustion products (CCPs) in this type of construction products meets all the criteria for safety and should be encouraged as a best practice for utilizing these valuable resources.

After publishing the rules, members of industry and environmental groups filed suits to address technical issues within the new rules. In late 2017 the oral arguments for the CCR case were held in the Fourth Circuit Court. While the court case decision is under review, EPA has announced that it intends to reconsider the CCR regulation and many of the issues under litigation will be addressed in modified rules. It is anticipated that EPA will publish proposed changes to the CCR regulations in 2018 with a target date of final rule changes in 2019.

In addition to the reconsideration efforts at EPA, Congress passed the Water Infrastructure Improvements for the Nation Act (WINN) on December 16, 2016 which included a section titled “Control of Coal Combustion Residuals” which amended Subtitle D of RCRA provides that States may elect to be the primary administering authority in lieu of a federal regulatory program. EPA published guidance documents in 2017 providing states with instruction on what each state must submit to EPA for review and approval of state authorization to administer the CCR rules under state control. Once a state files its program, EPA must review the state programs every twelve months.

Related to the CCR regulations, the Effluent Limitations Guidelines (ELG) under the Clean Water Act also impact ash ponds and CCR management methods. The new stringent rules were published November 3, 2015 (https://www.federalregister.gov/documents/2017/04/25/2017-07811/postponement-of-certain-compliance-dates-for-effluent-limitations-guidelines-and-standards-for-the) with implementation deadlines that would have impacted power plants in 2017. The rules were subject to judicial review due to litigation. On April 12, 2017 EPA announced it would reconsider the final rules and placed a stay on the compliance deadlines. This reconsideration essentially allows existing permitted wastewater discharges from ash impoundments to continue under the existing rules.

If you are a utility that burns coal at a generating plant covered by the rules, the impacts are many. Decisions must be made soon on whether old disposal units that are nearing full stage should be taken out of service and closed prior to the effective date of the rules (180 days after FR publication). Inactive units must be closed within 36 months after publication. The decision to stop placing coal combustion residuals (CCRs) in a disposal unit should be made ASAP. For other disposal units that will operate beyond the effective date, utilities must implement groundwater monitoring, record keeping and publishing data to a public website, inspections, review of all units vis-a-vis the new criteria and establish that the unit is protective of the environment. For new disposal units the new design and location criteria must be included in the planning process. In addition to these basic requirements many other detailed items must be met. Charah Solutions can assist utility staff in establishing a compliant program and implementing appropriate and economic solutions to meet the CCR rules.

If you are a user of coal ash, the rules provide continued assurance that products using recycled fly ash, bottom ash and gypsum are safe and protective of the environment. EPA’s criteria for disposal and the exemption of beneficial use both signal how important CCRs are to the national construction materials industries. The fact that EPA supports the continued beneficial use of CCRs paves the way for continued investment in science and projects which expand this resource utilization.

If you are an individual, the new EPA rules validate that CCRs are a valuable resource and can be safely used for various applications. This support for beneficial use saves natural resources by using recovered CCRs and avoids natural resource extraction while saving costs in producing new construction materials. Individuals can also take comfort in that EPA has established general criteria governing disposal of CCRs that is protective of health and the environment. States will be able to implement programs tailored to their specific needs of each state.

Building with concrete that contains fly ash can contribute significantly to earning points in the USGBC’s LEED program. Fly ash, in combination with other qualifying building materials, can contribute to points base on logistics, recycled content and innovation.

The Charah Solutions Way

Yes, Charah Solutions is experienced in managing large disposal sites and routinely handles millions of tons annually of coal combustion residuals (CCRs). We can also handle drainage, erosion control, synthetic liners, leachate collection systems and permit record keeping for landfill sites. Compliance with the new CCR requirements can be assured with a Charah Solutions designed operating plan that addresses each specific area of the landfill operation.

Charah Solutions will provide a dedicated team working for you to promote the use of CCPs produced at your station. We will diligently search and find opportunities that exist in the market to utilize CCPs from your station. Our experience and expertise in processing and marketing CCPs will maximize the value of your byproduct revenues.

Yes, Charah Solutions has the experience and expertise to construct your new ash landfills, new wastewater management ponds and compliant ash pond projects. As part of an integrated coal combustion residuals (CCR) compliance strategy, Charah Solutions can supply expertise on cost effective CCR management methods and new wastewater management facilities to meet the new regulations for ash facilities. Regardless of the complexity of the design, we have the engineering experience, technical expertise and equipment needed to meet your ash management construction needs.

Regulation of ash ponds is a key element of the new CCRs regulations. Making the correct decisions for ash pond compliance can have huge financial impacts on owners of these type units. Whether it is Clean Closure or Cap-in-Place, no two pond closures are exactly the same. Charah Solutions has vast experience in managing ash ponds and can provide our customers with hands on expertise in compliance operating strategy and deciding which method should be employed to manage the coal ash in compliance with the regulations and in an economical manner.

Yes, Charah Solutions has experience in designing and construction of dry fly ash collection and storage systems. Because we operate mechanical systems of every major type at utility plants across the US, we have a qualified perspective and knowledge of what works well and which equipment solution works best with each type of coal combustion residuals (CCR) products. Each plant has unique circumstances and Charah Solutions can help you choose the most economical system that accommodates a strong recycling program and an efficient disposal option.

In addition to a traditional “wet to dry conversion,” Charah Solutions offers an alternative approach to collecting fly ash which includes a PondX® solution that allows the wet ash slurry to be captured before reaching the pond and ash solids are removed from the slurry. The “clean slurry water” can then be recycled back to the plant for re-use, routed to a waste water treatment process and then discharged through an existing plant outfall. With multiple options for eliminating an ash impoundment, Charah Solutions can deliver an approach that offers the most attractive technical solution with the best economics while complying with the new CCR regulations.

Charah Solutions  offers an alternative approach to collecting bottom ash without sluicing into an impoundment. Our PondX® system can intercept the bottom ash slurry and remove the bottom ash before recycling the water back to the plant for reuse for bottom ash transfer. This eliminates the disposal impoundment and reduces the water demands for the power plant.

Charah Solutions manages plant needs for limestone at all levels of the value chain. Charah Solutions can assist in locating the most economical source of limestone to meet scrubber chemistry needs and can deliver a finished product in a form that meets the utility’s needs; from aggregate to ground limestone ready to inject into the scrubber.

Charah Solutions can design, build own and/or operate the limestone grinding facility to deliver the specified quality of limestone needed to meet the scrubber needs. We currently operate grinding capacity to meet the customer scrubber specifications. Our experience in grinding facility design, construction and operation will deliver value to your power plant. Charah Solutions will also provide the financial investment to meet your grinding facility needs. Contact Charah Solutions early in your project planning process to take advantage of our experience.