By Christine Harris and Dr. William Ahlert
In April 2015, EPA published its Disposal of Coal Combustion Residuals (CCR) from Electric Utilities final rule in the Federal Register. The rule regulates the safe disposal of coal ash, or CCRs, from coal-fired power plants. Consequently, many companies began the process of implementing the rule focused on closure or retrofit of ash impoundments and landfills from the solid waste perspective.
Though published under Subtitle D of the Resource Conservation and Recovery Act (RCRA), which is the public law that created the framework for the proper management of hazardous and non-hazardous waste, the rule also focuses on assessing and addressing groundwater impacts from coal ash disposal, specifically the leaking of contaminants into groundwater. It establishes distinct requirements associated with groundwater monitoring and reporting, required closure of CCR units based on groundwater and risk results, and record keeping and reporting requirements for each CCR facility. As a result, utilities have been faced with an increased need for understanding the groundwater requirements associated with the rule and coordination of compliance with current state solid waste regulatory requirements.
Filled coal ash pond. Image courtesy of the Department of Energy.
Why is it a water rule then? Under the rule as it currently stands, owners or operators of both active and inactive impoundments and landfills must monitor groundwater for potential contamination for 30 years or more. Groundwater underlying CCR regulated facilities may have sampling results that are above state and/or federal standards for those constituents listed in the CCR Rule.
Remediation of these impacts can take many forms, each of which operates on a specific timeline. Depending on the unique geologic setting of a given site, the primary form of remediation may be management of CCR material within the ponds (i.e., limiting infiltration via engineered cap or CCR removal). However, if ash has been stored below the water table, additional passive and/or active remediation may be required depending on groundwater sampling results.
There are many considerations to comply with the CCR Rule. Environmental factors play a central theme that must be taken into account as a CCR owner plans for impoundment closure or repurposing.
Based on the milestones established for existing active impoundments in the CCR Rule, initial assessments should have been completed, closure and post-closure care plans should have been posted, and the evaluation of detection groundwater monitoring should have occurred.
Aerial image of coal ash pond in North Carolina. Photo courtesy of Waterkeeper Alliance, published under Creative Commons (CC BY-NC-ND 2.0).
By the end of January 2018, the Annual Groundwater and Corrective Action report should have been posted to the facilities’ operating record. As of March 2, 2018, this report should have been posted to the facilities’ publicly accessible website. Depending on the results, utilities will need to make decisions within 90 days as to next steps. It is possible that by April 2018 impoundments with documented groundwater impacts above background will need to begin closure activities.
In December 2016, Congress passed the Water Infrastructure Improvements for the Nation (WIIN) Act. Certain provisions of this rule were directed to the CCR rule. Specifically, the act requires states to develop their own CCR rule or adopt the existing federal CCR rule. Further, state regulatory agencies would be responsible for enforcing compliance. As of January 2018, only one state plan, Oklahoma, has been public noticed for comment by the EPA.
Proposed Amendment to the CCR Rule
On March 2, 2018 the EPA issued the first of two proposed revisions to the 2015 CCR rule. The second proposed revision is expected to be announced in the fall of 2018. The rule was published to the Federal Register on March 15, 2018, and the 45-day comment period for interested parties to provide feedback to the EPA ended April 30, 2018. Additionally, EPA will most likely revise the proposed rule based on feedback received at a public hearing in the Washington, D.C., metro area.
The proposed rule:
• Provides clarification on the type and magnitude of non-groundwater releases that would require corrective action procedures.
• Adds boron to the list of Appendix IV constituents that trigger corrective action and potentially a required retrofit or closure of a CCR unit.
• Sets the height of woody and grassy vegetation for slope protection.
• Provides the ability, based on an EPA-approved state CCR permit program (as allowed under the WIIN Act) or where EPA is the permitting authority, to set “alternative performance standards” to allow states to use risk-based approaches to groundwater protection for constituents where no maximum contaminant level exists. Right now, these constituents are: cobalt, lead, molybdenum, lithium and boron. Additionally, states would have the ability to modify corrective action remedies, suspend groundwater monitoring requirements if no migration off-site is demonstrated, establish alternate time periods to comply with corrective actions, modify the post-closure care period (currently 30 years or more) and allow states to technically certify instead of current professional engineer certification for some requirements in the rule.
• Modifies the current rule to allow coal ash to be used in the construction of final cover systems for units that are closing with ash in place.
• Modifies the rule to allow facilities to qualify for alternative closure provisions based on the continued need to manage non-CCR waste streams that are currently managed by the impoundment.
Although there is still a long way to go before the proposed amendment is promulgated, some of the proposed revisions could impact facilities depending on the intent of their state regulatory agency to seek EPA approval of a state CCR permit program. In addition to Indian country, for states where there is no EPA-approved CCR permit program, EPA would serve as the permitting authority in those states subject to a congressional appropriation to carry out this function. EPA would have the same ability as a director of a state with an approved CCR program to apply the alternative performance standards. At this time, Congress has not provided appropriations to EPA to serve as the permitting authority in nonparticipating states, according to the Federal Register.
CCR Unit Closure Options
The CCR Rule allows for closure by removal of CCR material or by leaving material in place for both landfills and surface impoundments. This decision is typically based on regulatory factors such as groundwater position in relation to CCR and potential for, or existence of, groundwater impacts; economic and social factors such as comparative cost for capping versus removal; viability of finding a local disposal option; safety of increased truck traffic on local roadways; and land use factors such as on-site availability for new landfill construction and long-term plans for property usage.
When evaluating closure options, one of the most important considerations is understanding how the closure of the CCR unit impacts the hydrology of the site. If cap and close in place is considered, the following questions, at a minimum, need to be considered:
• Is the bottom of the landfill or impoundment in groundwater?
• What will the stormwater infiltration be and how will it impact the cap and close strategy?
• How will groundwater flow and quality change as a result?
• If closure by removal is being considered, the following questions, at a minimum, need to be considered:
• Is the bottom of the landfill or impoundment in groundwater? If so, how will dewatering be performed?
• Are groundwater monitoring reports available? If so, what constituents are currently being monitored?
• How clean is clean? Do you need to remove impacted media to establish cleanup standards?
At this point in time, active surface impoundments should have already collected the required groundwater samples and evaluated the results under the rule. These facilities should currently be either performing an alternative source determination or performing assessment monitoring. Depending on what the initial groundwater data showed compared to the rule requirements, corrective action options may be under consideration.
For inactive surface impoundments, companies should be planning for groundwater monitoring requirements. During this planning process, it is important to ensure that background wells are placed such that they are located hydrologically up gradient and the groundwater sampling and analysis plan should be evaluated. It is important when developing this plan to establish the best statistical approach for analyzing the data. The rule provides several options and it is recommended that the facility consult a statistician to review these options and identify the best one for the specific site.
For those sites currently performing assessment monitoring, work can be done to prepare for the corrective action phase (if required) as well as developing defensible options based on background conditions. During this period, companies should be considering what potential corrective actions may be required and evaluating their cost, effectiveness and regulatory approval potential. Each CCR site is unique in terms of location and hydrogeology.
Based on assessment monitoring, if corrective action is required, there are currently a number of proven passive and active options. These include monitored natural attenuation (MNA), pump and treat, slurry wall, and permeable reactive barrier walls. Each remediation option has strengths and weaknesses based on site hydrogeology and/or physical constraints (e.g., limited distance between impoundments and adjacent water bodies).
Additionally, when choosing a corrective action, the status of the overall facility needs to be considered. If the facility has been shut down or closed, choosing a corrective action that requires daily operation and routine oversight may not be the best long-term economic option.
Finally, if other groundwater corrective action treatments already exist at a site, they may have an impact on the selected corrective action for the CCR unit. For example, if a hydrocarbon plume is present on site and is being treated via anaerobic bioremediation, mixing of treated anaerobic groundwater with CCR-impacted groundwater may counteract the precipitation of the aluminum, iron, and manganese that is already present in the groundwater.
The reverse of this situation is also possible, where remediation of the CCR-impacted groundwater hampers or negates remediation of groundwater impacted by other sources/contaminants. Thus, understanding the nature and extent of all contaminant sources prior to remediation of CCR-impacted groundwater can save a CCR owner considerable time and effort after impoundment closure.
In evaluating the cost for complying with the CCR rule, a life cycle cost should be used including initial as well as ongoing maintenance costs. Companies may only look at the closure cost and not consider the cost of potential corrective action. While certain closure options may result in lower closure costs, if groundwater issues are present and corrective action is required, the total cost — both initial and ongoing operational expenses — may result in choosing a different closure option. Determining the actual cost for closure will be impacted by the size of the CCR unit, the amount of dewatering of the ash (if required) and the type of cover (if capped) selected. These costs need to be weighed against the potential additional costs of corrective action.
The CCR rule addresses concerns related to landfills and surface impoundments as a result of industry events that have occurred and provides guidance for CCR unit closure and requirements related to the closure that must be met. However, the long-term impact of the CCR rule is water-related — specifically the 30-year groundwater monitoring requirement. Groundwater conditions and flows should be considered when evaluating closure strategies. Understanding current groundwater conditions and early planning for potential remediation can result in overall reduced costs for the company in dealing with these issues.
About the Authors: Christine Harris is an industry-recognized program manager with an unmatched understanding of clients in the power market, having worked for a utility for 28 years. Currently, she is power generation regulatory compliance leader for HDR, working with clients and internal teams to share her decommissioning know-how and compliance expertise for regulations including 316(b), coal combustion residuals (CCR) and the effluent limitations guidelines (ELG).
Dr. William Ahlert is a vice president with HDR and the national lead for HDR’s Brownfields Cleanup, Power Plant Decommission and Coal Combustion Residuals Groundwater Remediation Programs. He received his masters and Ph.D. in environmental science from Rutgers University, conducting research in the areas of fate and transport of environmental contaminants in groundwater and surface water systems. He has been providing environmental consulting services for over 25 years.
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