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 end use unless fill material is imported to raise the elevation to fit the desired design. Due to its homogenous particle size, predictable geotechnical characteristics, low unit weight, relatively high shear strength and ease of handling and compaction, coal ash is an ideal material for such fills. Charah Solutions is highly experienced in the use of coal ash, placing it and compacting it in accordance with approved ASTM design criteria.

In reference to structural fills, the descriptions “lined” and “fully lined” refer to 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 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 always uses the best practices, materials and technology for structural fills. Charah Solutions recently completed 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 manufactured with quality fly ash demonstrates all of the following technical advantages: added long term strength, durability, lower permeability, improved resistance to sulfate attack, increased pumpability and workability, and improved finish product quality. Additionally, concrete with fly ash is less expensive and more sustainable since the carbon footprint is reduced.

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.

Bottom ash is commonly used in a wide variety of construction material applications. Charah Solutions has the expertise to evaluate ash sources and determine if they qualify for use in any application, and we have a successful track record of finding markets for the beneficial use of bottom ash.


On April 17, 2015, EPA published the Coal Combustion Residuals (CCR) Regulations in the Federal Register. These published requirements regulate CCRs as non-hazardous materials under RCRA Subtitle D. The regulations established national criteria under which states can govern CCRs in a manner similar to municipal solid wastes, addressing CCR disposal from utility boilers that burn greater than 51% coal fuels and exempting beneficial use of CCRs. The new regulations define “beneficial use” and also provide a mechanism whereby 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 also require 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 by states which 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 entitled “Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard” confirms that the use of ash and coal combustion products (CCPs) in these types 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. On April 18, 2016, the EPA reached a Settlement Agreement with litigants to address four claims and the EPA’s request for the Court to remand the rule back for amendment to address remaining claims. On June 14, 2016, the Fourth Circuit Court (DC) remanded the rules back to EPA to make changes to address litigation. On August 5, 2016, the EPA amended CCR Regulations to include inactive ponds.

In late 2017, the oral arguments for the remaining CCR case issues were held in the Fourth Circuit Court. While the court case decision remains under review, EPA announced in 2017 that it intended to reconsider the CCR regulations in two phases and address many of the issues under litigation. 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” amending Subtitle D of RCRA and providing 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, the EPA must review the state programs every twelve months.

In March 2018, EPA proposed Phase 1 changes to the CCR regulations. After a public comment process and OMB review, EPA released a Phase 1-Part 1 pre-publication copy of the amendments on July 18, 2018. EPA has a target to address Phase 2 proposed rules in 2018, with a final rule change in 2019. Within the Phase 1-Part 1 amendments, EPA addresses three major areas and notes that a forthcoming second part rule will address additional Court remand items. The major provisions are:

(1) Provides states with approved CCR programs authority to use alternate performance standards as directed by WIIN. Also allows states to certify compliance items in addition to P.E.s.

(2) Revises groundwater protection standards for four constituents (Cobalt, Lead, Lithium & Molybdenum) that have no maximum contaminant levels (MCL) under the Safe Drinking Water Act. Boron was not addressed in Phase 1 – Part 1.

(3) Provides an extension in deadlines for certain units to cease receiving CCRs under two very specific circumstances; if a detection of groundwater with constituents and also where the unit cannot meet the five feet vertical separation location restriction. This action aligns with the timeline for new NPDES rules coming in 2019-2020 and extends pond life until 10/31/2020. All other location restrictions remain intact.

EPA is still required to address Court remand items that were not addressed in this Phase 1-Part 1 rule within 2018. Remaining Court remand items will be addressed in a forthcoming amendment. The EPA has also previously indicated that Phase 2 modification rules will be proposed in fall of 2018 with final rules in 2019.

One of the remaining items to be addressed by EPA is inclusion of Boron in the groundwater constituent list.

After EPA published its guidance for states to submit their CCR regulatory programs, several states have initiated the review/certification process. On June 28, 2018, Oklahoma was authorized as the first State to receive approval (https://www.gpo.gov/fdsys/pkg/FR-2018-06-28/pdf/2018-13461.pdf) to administer their own CCR Program effective July 31, 2018.

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, the 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, EPA coal ash regulations impact you in many ways. For inactive surface impoundments and disposal units that will operate beyond the effective date, utilities must implement groundwater monitoring, record keeping and data publishing 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 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. EPA support for the continued beneficial use of CCRs paves the way for continued investment in science and projects that 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. Since the utilization of CCRs as a replacement for cement in concrete minimizes the emissions from the cement manufacturing process and reduces imported cement, the U.S. balance of trade is enhanced. Individuals can also take comfort that EPA has established general criteria governing disposal of CCRs that is protective of health and the environment. Accordingly, states will be able to implement programs tailored to their specific needs.

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 based 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 the design and installation needs for drainage, erosion control, synthetic liners and leachate collection systems, and perform 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 that will work 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. In addition, Charah Solutions can provide beneficiation technology solutions in situations where the CCRs need processing and quality improvement to meet market specifications. 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 ash management methods and new wastewater management facilities to meet the new regulations for CCR facilities. Regardless of the complexity of the design, we can provide 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 a huge financial impact on the owners of these types of units. Whether it is Closure by Removal or Cap-in-Place, no two pond closures are exactly the same. Charah Solutions has vast experience in managing ash ponds. We can provide our customers with hands on expertise in compliance operating strategy and selecting a method to manage the coal ash safely and in compliance with current regulations, and in an economical manner.

Yes, Charah Solutions has experience and expertise in the design and construction of dry fly ash collection and storage systems. Because we operate mechanical systems of every major type at utility plants across the U.S., we have a qualified perspective and knowledge of what works well and which equipment solution works best with each type of CCR product. 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. This approach 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/or 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 and 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 needed to deliver the specified quality of limestone that meets the client’s scrubber requirements. 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 capital investment to meet your grinding facility needs. Contact Charah Solutions early in your project planning process to take full advantage of our experience.