December 18, 2020

Rule Allows Alternate Liner Demonstration for CCR Impoundments

On November 12, 2020 [85 FR 72506], EPA finalized revisions to the coal combustion residues (CCR) regulations in Part 257, Subpart D. The revisions allow facilities to request approval to operate an existing CCR surface impoundment with an alternate liner. This rule took effect on December 14, 2020. However, in Oklahoma and Georgia, the states with EPA-approved CCR programs, this rule does not take effect until those states adopt it. [85 FR 72536]

Alternate liner demonstration

In 2018, the Utility Solid Waste Activities Group et al. vs. EPA court decision vacated provisions in Part 257, Subpart D regulating clay-lined surface impoundments differently than unlined impoundments. Consequently, those clay-lined CCR impoundments would need to retrofit or close. Following the decision, industry groups claimed that the performance of some clay-lined impoundments is equivalent to or even superior to that of liners required by the 2015 CCR rule. Therefore, EPA is finalizing a process for facilities with clay-lined surface impoundments to submit an alternate liner demonstration to the agency, showing there is no reasonable probability of adverse effects on human health or the environment. The alternate liner demonstration is a two-step process: an initial application followed by submittal of the alternate liner demonstration data. The demonstration is required only if the initial application is approved.

Initial application

The initial application must contain seven components [§257.71(d)(1)(i)]:

  1. An application letter declaring the facility’s intent to submit an alternate liner demonstration for a specific unit at a specific location;
  2. Certification that the unit is in compliance with applicable CCR regulations;
  3. Documentation of the groundwater monitoring network and documentation that the network is in compliance with the groundwater monitoring and detection requirements of §§257.91, 257.93, and 257.94;
  4. Documentation that the location restrictions of §§257.60 through 257.64 are met;
  5. The most recent structural stability and safety factor assessments;
  6. Design specifications for any engineered liner components and all data/analysis showing the liner is of good quality and in line with proven and accepted engineering practices; and
  7. Demonstration that there is no reasonable probability that a complete and direct transport pathway can exist between the CCR impoundment and any nearby body of water.

Alternate liner demonstration data

If the application is approved, the facility will proceed to the actual alternate liner demonstration. The underlying goal of the demonstration is to show continued operation of the impoundment will not result in groundwater concentrations in the uppermost aquifer at levels above groundwater protection standards. The two lines of evidence used in the demonstration are a characterization of site hydrogeology and the potential for infiltration through liners and underlying soils. These lines of evidence are incorporated into a mathematical model calculating the potential groundwater concentrations that may result in wells downgradient of the CCR impoundment.

Characterization of site hydrogeology includes four aspects [§257.71(d)(1)(ii)(A)]:

  1. Measurements of the hydraulic conductivity in the uppermost aquifer from existing monitoring wells;
  2. Subsurface samples collected to characterize site hydrogeology;
  3. Conceptual site models with cross-sectional depictions of site stratigraphy; and
  4. A narrative description of site geological history.

The second line of evidence, potential for infiltration, includes four aspects [§257.71(d)(1)(ii)(B)]:

  1. The number and location of hydraulic conductivity samples;
  2. Documentation that the liquid used to measure long-term hydraulic conductivity reflects the pH and major ion composition of the impoundment porewater;
  3. Documentation that the samples used to represent hydraulic conductivity are handled in a manner ensuring the macrostructure of the soil is not physically disturbed during collection, transport, or analysis; and
  4. Test termination data ensuring, within acceptable tolerance limits, that equilibrium has been achieved between the inflow and outflow for both electrical conductivity and pH.


The modeling methodology must be documented and justified, well-established and validated, and have publicly available background documentation. Proprietary models not available for public review will not be considered appropriate for use in a demonstration. Model outputs must show there is no reasonable probability that peak groundwater concentrations for all Part 257, Appendix IV constituents will exceed the groundwater protection standard at the waste boundary throughout the active life of the unit. The demonstration must include results attributed both to the impoundment in isolation and in addition to background. [§257.71(d)(1)(ii)(C)]

Application and demonstration approval

The deadline for the initial application to EPA or the participating state director was November 30, 2020. Provided the application is complete, it will be posted to a docket on where the public will be able to submit comments for 20 days. EPA intends to review the application and public comments within 60 days and make a decision by February 1, 2021. Facilities will need to post EPA’s decision to their publicly accessible CCR websites. If the application is approved, facilities will need to submit their alternate liner demonstration by November 30, 2021. [§257.71(d)(2)(ii)]

If a facility cannot meet the November 30, 2021 alternate liner demonstration deadline, it may submit a one-time request for deadline extension by September 1, 2021. An extension may be requested due to analytical limitations related to the measurement or stabilization of hydraulic conductivity.

Once the alternate liner demonstration is submitted, it will then be added to the appropriate docket at where the public will have 30 days to provide comment. When EPA or the participating state makes a final decision, the decision, along with a copy of the demonstration, must be posted to the facility’s publicly accessible CCR website. If the demonstration is denied, the impoundment will need to close by the date specified in the decision, or the facility can apply for one of the site-specific alternative closure deadlines found in §257.103(f).

If the demonstration is approved, the impoundment may continue to operate; however, the unit must remain in detection monitoring. Upon detection of a statistically significant increase over background of an Appendix III constituent, the facility must proceed to the assessment monitoring regulations in §257.95. If this occurs, the facility will need to conduct groundwater monitoring and trend analysis for Appendix IV constituents. If the trendline is steep enough to result in an exceedance of a groundwater protection standard at any point during the active life of the impoundment, the facility must close the unit.


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This document addresses issues of a general nature related to the federal RCRA regulations. Persons evaluating specific circumstances dealing with the RCRA regulations should review state and local laws and regulations, which may be more stringent than federal requirements. In addition, the assistance of a qualified professional should be enlisted to address any site-specific circumstances.