US EPA Proposes Risk-Based Revisions to Legacy Coal Ash Regulations

April 26, 2026

US EPA’s proposed rule, issued April 13, 2026, would expand the use of site-specific, risk-based approaches for coal ash management and disposal and is open for comment through June 12, 2026.

The US Environmental Protection Agency (US EPA) has issued a proposed rule that would revise several provisions of the federal regulations governing the management and disposal of coal combustion residuals (CCR), including requirements applicable to legacy coal ash surface impoundments and CCR management units (CCRMUs).  The proposal was published in the Federal Register on April 13, 2026, and is open for public comment through June 12, 2026.

The proposed rule includes several provisions that would allow for expanded use of site‑specific, risk‑based approaches.  Notable elements of the proposal include:

• Ensuring Closure Is Protective of Human Health and the Environment:  US EPA is proposing that permitting authorities be allowed to make site-specific determinations regarding closure requirements based on an ability to demonstrate that a selected closure option does not pose an unreasonable risk to human health or the environment.

• Risk-Based Corrective Action:  US EPA is seeking comments on whether permitting agencies can approve corrective action remedies based on the results of a site-specific risk assessment.

• Development of Health‑Based Alternative Groundwater Standards:  US EPA is proposing to allow the use of health‑based alternative groundwater protection standards as site‑specific groundwater cleanup levels for sites with an approved federal or state CCR permit.  This proposed revision would be relevant for cobalt, lithium, and molybdenum.

Why This Proposed Rule Matters
If finalized, these revisions could significantly affect how regulated facilities evaluate closure, groundwater impacts, and corrective action obligations at coal ash sites.  In particular, US EPA’s proposal signals an increased role for human health risk assessment and site‑specific technical analyses.

How Gradient Can Help
Gradient has been at the forefront of developing and advancing recommendations to US EPA for risk‑based strategies for coal ash regulation, including the appropriate use of human health and environmental risk assessment to inform decisions.  In fact, Gradient’s analyses from November 2025, “Technical Evaluation of the Environmental Protection Agency’s 2024 Risk Assessment of CCR Management Units,” prepared for the Utility Solid Waste Activities Group and National Rural Electric Cooperative Association, are highlighted in the current proposed rule, including:

• Conducting human health and environmental risk assessments to support closure demonstrations;
• Developing site‑specific, health‑based alternative groundwater standards;
• Modeling contaminant fate and transport in groundwater and surface water; and
• Providing technical support for regulatory engagement, public communication, and permitting.

We would be happy to discuss how these proposed changes may affect your site and how Gradient can support compliance and strategic planning under the evolving coal ash regulatory framework.

Contacts:
Ari S. Lewis, M.S.
Principal

Andy Bittner, M.Eng., PE
Principal

John Kondziolka, M.S.
Principal