Managing CCR Groundwater in an Evolving Landscape

For utilities managing coal combustion residuals (CCR) at active and recently closed facilities, the work is entering a more demanding phase.

The initial years following the EPA’s 2015 CCR Rule focused on compliance, including installing groundwater monitoring systems, collecting and analyzing groundwater data, and advancing CCR unit closure activities. While some facilities regulated by the 2015 CCR Rule have entered corrective action, others are still evaluating options where additional and more sophisticated information may be needed.

Utilities learned that decisions made during the initial stages of compliance can shape long-term remediation obligations, operational costs, and facilities management strategies for decades. As a result, technically rigorous, site-specific interpretation is becoming increasingly important to achieving cost-effective and defensible outcomes.

For facilities that have progressed beyond initial compliance activities, the next phase is often the most significant. Corrective action is less prescriptive than earlier phases and depends heavily on site-specific conditions. It also carries greater financial and regulatory consequences, making sound technical interpretation critical.

A More Complex Regulatory Framework 

At the same time, the 2024 CCR Legacy Rule has expanded the number of regulated facilities by bringing many units that were closed before 2015 into the process. The industry is now operating across multiple phases simultaneously, with many newly regulated facilities progressing through the same early evaluation, monitoring, and data collection activities that followed implementation of the 2015 CCR Rule.

Revisions to the CCR framework proposed in April 2026 would introduce additional complexity for both active and legacy facilities. While the proposed rule changes are currently under review, and details continue to evolve, early interpretations suggest a more nuanced outcome than a simple tightening or relaxing of requirements.

The proposal includes potential changes to timelines, applicability, and compliance methods, along with greater flexibility through risk-based, site-specific approaches. It may also expand the role of regulatory review and permitting, reducing reliance on self-implementation. These changes may shift, rather than reduce the regulatory burden.

Applying Lessons from 2015 Rule Implementation

Many utilities that worked through the 2015 CCR Rule gained a better understanding of how groundwater monitoring systems influence future outcomes, how data are interpreted under regulatory review, and where challenges are likely to arise. They also saw how different technical approaches affect long-term costs.

The 2024 CCR Legacy Rule built upon a framework that utilities already know. The sequence of evaluation, monitoring, and potential corrective action is familiar. This experience can make a difference going forward, no matter how the 2026 revisions evolve.

One of the most important lessons learned under the 2015 CCR Rule is that groundwater exceedances alone do not fully explain constituent sources or long-term behavior. CCR-related groundwater conditions are often influenced by complex interactions between site geology, mineralogy, geochemistry, and naturally occurring (i.e., geogenic) background conditions. As a result, similar monitoring results may lead to very different regulatory and corrective action outcomes depending on how site conditions are evaluated and documented.

For this reason, utilities increasingly benefit from developing detailed geochemical conceptual site models (CSMs) early in the evaluation process and updating them as relevant data are generated. A robust geochemical CSM integrates hydrogeology, groundwater chemistry, mineralogy, constituent concentration trends, site history, and subsurface geochemical processes to establish a technically supported understanding of site conditions. Focused laboratory geochemical testing can be a useful tool to inform a CSM.

This early evaluation can help determine whether an alternative source demonstration (ASD) or geogenic study may be valuable before utilities commit to corrective action. Geochemical and mineralogical investigations may demonstrate that observed groundwater concentrations are influenced partially or entirely by naturally occurring conditions rather than CCR releases.

The same technical studies used to develop a defensible CSM and evaluate the natural occurrence of CCR constituents (for ASD and background groundwater quality purposes) may also inform cost-effective corrective action options such as monitored natural attenuation (MNA) and focused in situ geochemical treatments (e.g., injections). Additional laboratory treatability studies and field pilot tests are usually required for groundwater corrective action evaluation. Depending upon site conditions, MNA and in situ technologies can greatly reduce the scope and associated cost of groundwater corrective action.

Using Technical Interpretation to Improve Corrective Action Strategies

Even where ASDs are not ultimately supportable, the geochemical CSM remains critical for evaluating corrective action alternatives. A more detailed understanding of constituent mobility, attenuation mechanisms, groundwater geochemistry, and subsurface conditions can help utilities identify targeted and more cost-effective remediation strategies. Laboratory treatability testing may be integrated with field work (i.e., pre-design investigations) to evaluate treatment options, refine CSMs, and reduce uncertainty during corrective action evaluation and design. This supports decisions that are both technically sound and less costly. Without this level of technical interpretation, utilities may default to more conventional remedies that carry substantial long-term operational and maintenance obligations.

Rather than relying immediately on large-scale treatment systems such as pump-and-treat, some facilities may be well suited to approaches that combine MNA with focused in situ treatment (e.g., injections) in areas of elevated CCR constituent concentrations. When supported by sufficient technical data and regulatory acceptance, these strategies may reduce long-term operational complexity while still meeting corrective action objectives.

The effectiveness of these approaches depends heavily on integrating multiple technical disciplines throughout the evaluation process, including hydrogeologic characterization, groundwater chemistry evaluation, mineralogical analysis of solids, geochemical modeling, laboratory treatability and related testing, targeted field investigations, environmental engineering, constructability, and implementation considerations.

Together, these tools help reduce uncertainty, refine conceptual understanding, and support technically sound and cost-effective decisions.

A More Strategic Phase for CCR Groundwater Management

Although the industry has gained significant experience over the past decade, the current phase of CCR groundwater management is more technically and strategically demanding than the initial compliance period. Utilities are now balancing current and future regulatory requirements with long-term cost, risk, and technical feasibility.

Moving beyond compliance monitoring requires both an understanding of the rules and the ability to interpret site conditions, evaluate alternatives, and support decisions that will stand up to regulatory and external review.

Joe Smith, PE, is a Managing Engineer and Wayne Weber, PE, PG, is a Principal Engineer at Anchor QEA.

Get in touch with Joe Smith to learn more.