The Environmental Protection Agency (EPA) recently reversed a previous decision, allowing the Salt River Project (SRP) to maintain a clay liner at its Coronado Generating Station’s coal ash evaporation pond. This facility, located in St. Johns near the New Mexico border, has been a focal point of environmental regulatory scrutiny.
The EPA’s earlier stance required a plastic liner for such ponds, a rule in place since 2018. However, SRP sought an exemption in 2020, arguing that the clay liner would not pose a contamination risk to local water sources.
In a 2023 tentative denial, followed by a formal rejection, the EPA cited non-compliance in soil characteristics and monitoring systems. Yet, after SRP’s subsequent request for reconsideration and its submission of additional technical data, the agency approved the clay liner use on July 23.
Sandy Bahr of the Sierra Club criticized the EPA’s reversal, asserting, “SRP didn’t demonstrate anything more about their monitoring, didn’t demonstrate anything more that it wasn’t contaminating, and they certainly didn’t have a different liner.”
SRP contends that its technical assessments validate the natural clay’s effectiveness as a barrier, equivalent to a synthetic liner. Furthermore, they claim that replacing the clay liner would cost over $90 million and require 94 additional acres for waste disposal.
The approval allows SRP to continue operations with the existing pond setup while an extensive review process ensues. A comprehensive demonstration report is anticipated by mid-2027.
Background on Coal Ash Regulations
In response to significant coal ash contamination incidents in 2015, the EPA enacted its inaugural coal combustion residuals disposal regulations. Coal ash contains hazardous substances, including neurotoxins and carcinogens, posing serious health risks if they infiltrate water supplies.
Following a 2018 judicial ruling, coal ash ponds lacking plastic liners were deemed environmentally hazardous and slated for closure or retrofitting. Nevertheless, a 2020 EPA ruling provided utilities with an “alternate liner demonstration” pathway, enabling the use of existing soil or clay liners if they could prove no leakage risks.
Environmental advocates, such as Bahr, oppose non-plastic liners due to potential leakage risks. She stated, “We want to see strong protections in place requiring those liners. Even from a basic, common sense perspective, having ponds that have high levels of pollution without a lining is just a bad idea.”
A Duke University study aligns with these concerns, indicating increased contamination risks for water supplies when relying on clay or soil liners instead of plastic ones.
