Utilities face many challenges as they move forward developing programs to deal with disposal or recycling of coal combustion residuals (CCR). The U.S. Environmental Protection Agency (EPA) recently proposed changes to the 2015-enacted federal coal ash rule and issued a proposed Federal permitting program rule for CCR.
SCS Engineers closely follows developments relating to coal ash disposal. The company works with landfill operators, utilities, and others who deal with CCR to meet the challenges of proper waste management as federal, state, and local regulations evolve.
In addition to evaluating the impact of proposed rule changes and permitting programs, many utilities are currently working to address groundwater impacts from CCR units monitored under the current Federal CCR rules (40 CFR 257 Subpart D—Standards for the Disposal of Coal Combustion Residuals in Landfills and Surface Impoundments). Based on timing in the CCR rule, utilities have recently completed an Assessment of Corrective Measures (ACM) for groundwater impacts and are working on selecting a remedy for the groundwater impacts identified.
The remedies for CCR units not already closed include some form of source control, along with strategies to limit impacts to groundwater. The most prevalent remedies today include closure-in-place, or cap-in-place, of coal ash storage sites, or closure-by-removal, in which CCR is dewatered and excavated, then transported to a lined landfill.
“The answer to this question is wide and varied,” said Eric Nelson, a vice president with SCS. Nelson is one of the company’s national experts for electric utilities, and an experienced engineer and hydrogeologist. “In part, it depends on the situation” Nelson noted that remedies for disposal of waste such as CCR from power plants could differ from the disposal of municipal solid waste (MSW) or everyday trash.
“Is the landfill or impoundment already closed or capped, is it active or inactive, what type of CCR or waste (is being disposed of)?” Nelson said. “Then there’s the physical setting, the geology, the receptors or lack of receptors. My opinion is that the industry is in a tough spot because the remedy selection process is strongly influenced by opinion and widely varied regulatory climates.”
“For instance, selecting a remedy, which in many cases will include closing a surface impoundment, that leaves CCR in place feels risky to some due to what is happening in places like the Carolinas and Virginia,” Nelson said. “Anything short of exhumation and re-disposal seems to be cast as insufficient by some when closure in place is a tested and proven response in other arenas [such as MSW]. A one-size-fits-all solution isn’t appropriate.”
Some utilities have moved forward with complete excavation, removing ash, and re-disposing it in a lined landfill. Some of these projects have likely been influenced by local efforts to dictate the remedy selection process through negotiation or legislation. The fact that some utilities have selected closure-by-removal does not mean this remedy is suitable in all situations.
Sherren Clark, vice president and Solid Waste Services Division leader for the Upper Midwest Region of SCS, said: “In terms of remedy selection, one key difference between MSW and CCR sites has been that for CCR sites, total CCR removal is an option that has been put on the table, and is being implemented at some sites, both small and large. For MSW, total waste removal has very rarely been the chosen approach and has typically been thought of as infeasible unless there were other financial drivers supporting that choice. The typical approaches for MSW sites have focused on source control options, such as an improved cap or enhanced landfill gas collection systems.”
Nelson said that engineers working on plans for CCR disposal could look at what’s been done at MSW sites.
“We might discuss the various approaches to corrective action that are described in some early guidance for MSW work,” Nelson said, pointing to EPA Technical Manual EPA530-R-93-017, which deals with solid waste disposal facility criteria and addresses active remediation, plume containment, and source control. “I believe there are significant guidance and experience we can draw from the MSW arena on the different remedies and how to evaluate them.”
Nelson said that “potential remedies must be evaluated according to the requirements in 40 CFR 257.96 and 257.97,” which are EPA rules outlined in the Electronic Code of Federal Regulations (e-CFR). Part 257 details Criteria for Classification of Solid Waste Disposal Facilities and Practices, including Subpart D-Standards for the Disposal of Coal Combustion Residuals in Landfills and Surface Impoundments, including groundwater monitoring and corrective action. Section 257.96 deals with ACMs. Nelson notes an important distinction with this approach: “One important note is that cost cannot be considered as it is in the similar rules for MSW.”
Jennifer Robb, vice president and project director with SCS’s Solid Waste Services Division in Reston, Virginia, said programs for the disposal of MSW “are pretty much identical to the process a [CCR] site has to go through. The only difference is the constituents they sample the groundwater for. The CCR sites, they’re going to have an issue with metals. The big problem with that is, a lot of the metals are naturally occurring.”
Robb noted that’s where the alternate source demonstration (ASD) comes in, to determine the source of contaminants, and whether a CCR pond or other ash storage facility is responsible for causing levels of contaminants to excess groundwater protection standards.
Evolving Regulatory Landscape
The Environmental Protection Agency (EPA) is proposing a streamlined, efficient federal permitting program for the disposal of coal combustion residuals (CCR) in surface impoundments and landfills, which includes electronic permitting. The new rules are designed to offer utilities more flexibility and provide regulatory clarity.
(1) In August 2019, EPA proposed amendments to CCR regulations that encourage appropriate beneficial re-use and clarity on managing coal ash piles. The proposal would also enhance transparency by making facility information more readily available to the public.
(2) A November 4, 2019, proposal establishes August 2020 as the date for utilities to stop receipt of waste in affected impoundments. It gives utilities the ability to demonstrate the need to develop new, environmentally protective waste disposal technology subject to EPA approval.
(3) On December 19, 2019, EPA proposed a federal permitting program for coal ash disposal units. The proposal includes requirements for federal CCR permit applications, content, and modification, as well as procedural requirements. EPA would implement the permit program at CCR units in states that have not submitted their own CCR permit program for approval. EPA already accepted and approved state permitting programs in Oklahoma and Georgia and is working with others to develop their programs. On December 16, 2019, the EPA Administrator signed a Federal Register notice approving Georgia’s state permit program for the management of CCR.
The November proposal addresses the deadline to stop accepting waste for unlined surface impoundments managing coal ash. It includes a new date of August 31, 2020, for facilities to stop placing waste into these units and either retrofit them or begin closure. The proposal would allow certain facilities additional time to develop an alternate capacity to manage their waste streams before initiating closure of surface impoundments. It would also re-classify clay-lined surface impoundments from “lined” to “unlined,” which means that clay-lined impoundments would have to be retrofitted or closed. Under the proposal, all unlined units would have to be retrofitted or close, not just those that detect groundwater contamination above regulatory levels.
The 60-day comment period on the November proposal closes January 31, 2020. The EPA will conduct a virtual public hearing about the proposed rule on January 7, 2020, at 9 a.m. Eastern Time. Register for the meeting to learn more. A 60-day comment period for the proposed federal permitting program will begin once the rule is published in the Federal Register.
This blog series highlighting the experience and expertise of SCS Engineers staff will continue with a look at examples of remedies for coal ash disposal and storage. If you have questions, contact the authors by selecting one of their names, or email us at .
Jeff Marshall, PE, SCS Engineers will be presenting the topic of Hydrogen Sulfide Issues at CCR and MSW Co-Disposal Sites during the EREF and NWRA sponsored Coal Ash Management Forum in July.
The co-disposal of municipal solid waste and coal combustion residuals – particularly flue gas desulfurization (FGD) material – poses a significant concern regarding the generation of hydrogen sulfide gas. Hydrogen sulfide has an exceptionally low odor threshold, and can pose serious health concerns at higher concentrations. This presentation will identify the biological, chemical and physical conditions necessary for FGD decomposition and hydrogen sulfide generation. Recommendations for reducing the potential for FGD decomposition at co-disposal facilities will be presented. Technologies for the removal and treatment of hydrogen sulfide from landfill gas will also be addressed.
Jeff Marshall, PE, is a Vice President of SCS Engineers and the Practice Leader for Environmental Services in the Mid-Atlantic region. He also serves as the SCS National Expert for Innovative Technologies. He has a diversified background in environmental engineering and management, with emphasis on the chemical and human health aspects of hazardous materials and wastes. Mr. Marshall’s experience with hydrogen sulfide, odors, sulfate decomposition in landfills, and ash issues includes scores of projects dating back to the 1980s.