Regulatory Developments

EPA Receives Petition Seeking RCRA and TSCA Regulatory Action for Phosphogypsum and Process Wastewater

March 12, 2021 PRINT

On February 8, 2021, the U.S. Environmental Protection Agency (EPA) received a petition seeking a rule reversing EPA’s 1991 Bevill regulatory determination excluding phosphogypsum and process wastewater from phosphoric acid production (process wastewater) from hazardous waste regulation under Subtitle C of the Resource Conservation and Recovery Act (RCRA). The petition also urges EPA to promulgate regulations under RCRA Subtitle C governing the safe treatment, storage, and disposal of phosphogypsum and process wastewater as RCRA hazardous waste. Under Section 21 of the Toxic Substances Control Act (TSCA), Petitioners request that EPA initiate the prioritization process to designate phosphogypsum and process wastewater as high-priority substances for risk evaluation under TSCA Section 6, issue a TSCA Section 4 test rule for disposed phosphogypsum, and issue a significant new use rule (SNUR) under TSCA Section 5 for phosphogypsum used in road construction. In its letter acknowledging receipt of the petition, EPA notes that under TSCA Section 21, EPA has 90 days after the date of filing to grant or deny the petition. If EPA denies the petition, EPA will publish the reasons for such a denial in the Federal Register.

EPA’s 1991 Bevill Determination Is Reversible

In 1990, EPA completed its study of phosphogypsum under RCRA and submitted the required report to Congress for 20 mineral processing special wastes, including phosphogypsum and process wastewater. According to Petitioners, the study “found widespread groundwater contamination at phosphogypsum stack sites including contaminated off-site wells, the potential for drinking water source exposures, several documented damage cases that impacted both ground and surface waters and threatened and harmed aquatic life, increased air pathway cancer risk for those living near stacks, and varied and inadequate state regulation.” Petitioners state that due to costs to the industry in complying with a Subtitle C program, however, EPA published a determination in 1991 that exempted phosphogypsum and process wastewater (as well as all other special wastes) from Subtitle C regulation.

Petitioners argue that EPA is not precluded from conducting additional study or revisiting the initial determination at a later date when more information about the present and potential hazard becomes known. Petitioners note that in a 1997 rulemaking on various mining waste issues, EPA suggested it would revisit its Bevill regulatory determinations for certain “high-risk” mining wastes. According to Petitioners, multiple large-volume releases have occurred in the phosphoric acid production waste context that are similar to the 2010 breach in an impoundment pond at a Kingston, Tennessee, power plant that released more than one billion gallons of coal ash slurry. After the 2010 breach, EPA revisited its May 2000 Bevill determination excluding coal combustion residuals from Subtitle C requirements and proposed a reversal of its Bevill determination and regulation under Subtitle C, or in the alternative, minimum federal standards under Subtitle D.

Petitioners further argue that EPA’s intent to use RCRA and Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) enforcement authorities to manage the substantial present and future hazards posed by phosphogypsum and process wastewater in lieu of Subtitle C regulation is contrary to RCRA’s statutory purpose. According to Petitioners, RCRA and its implementing regulations are designed to prevent harm caused by solid and hazardous wastes and to protect adequately human health and the environment by ensuring these wastes are properly managed and disposed of in the first place. Petitioners state that EPA “cannot continue to ignore this mandate by pointing to authority -- rarely exercised in the case of mineral processing industries anyway -- to enforce corrective action clean-up or abatement orders after the harm has already occurred (i.e., remediation of site-specific groundwater contamination) under a higher imminent and substantial endangerment standard.” Instead, EPA must ensure proper management and disposal of phosphogypsum and process wastewater under RCRA Subtitle C by reversing its Bevill determination and listing the wastes as hazardous before considering future corrective actions, “as said corrective actions would not be necessary if the waste were properly and safely managed.”

Phosphogypsum and Process Wastewater Require RCRA Subtitle C Regulation

Petitioners state that RCRA regulations provide that a solid waste not excluded from regulation as a hazardous waste may be designated as a listed “toxic waste” (hazardous waste with toxic constituent(s)) or a “characteristic hazardous waste.” The solid waste may be listed as a toxic waste if it contains a listed toxic constituent and an analysis of 11 enumerated factors supports a conclusion that the waste is “capable of posing a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported or disposed of, or otherwise managed.” A characteristic hazardous waste must exhibit one of four hazardous waste characteristics: ignitability; corrosivity (as determined by pH); reactivity; or toxicity (as determined by a leaching test). According to Petitioners, phosphogypsum contains toxic constituents, and an analysis of the 11 factors shows that the waste is capable of posing substantial hazards and must be listed as a toxic waste. Petitioners state that process wastewater exhibits the characteristics of corrosivity and toxicity, satisfying the criteria for designation as a characteristic hazardous waste.

Prioritization for Risk Evaluation under TSCA Section 6

Petitioners note that although there is a preference for prioritizing substances listed on the 2014 TSCA Work Plan, “EPA retains discretion to initiate prioritization for substances not on the work plan, like phosphogypsum and process wastewater from phosphoric acid production, since TSCA regulations require only that 50 percent of the substances currently undergoing risk evaluation are drawn from the work plan.” Petitioners state that to initiate prioritization, the TSCA regulations “require only that EPA believe information on relative hazard and exposure potential necessary to prioritize the substance is reasonably available.” According to Petitioners, the information and findings in EPA’s 1990 Report to Congress on Special Wastes from Mineral Processing and any supplemental analysis concerning the risks of phosphogypsum and process wastewater to human health and the environment “are certainly reasonably available and provide enough information on the risks of these substances to not only initiate prioritization but also to make a high priority designation based on the exposure potential and substantial hazard findings in that report alone, especially when considering that both the size of the stacks and exposed populations have greatly increased since 1990.”

TSCA Section 4 Test Rule

Petitioners argue that most current, published phosphogypsum research focuses on potential commercial uses that EPA has already banned under a 1989 final rule announcing final decisions on National Emission Standards for Hazardous Air Pollutants (NESHAP) for emissions of radionuclides due to the risk of widespread radon exposure. Petitioners maintain that updated information on population-level exposure risks for radionuclide constituents and radon emissions for phosphogypsum stack systems is necessary because the population within 80 kilometers of each phosphogypsum stack has likely greatly increased, as well as the number and size of the stacks themselves. According to Petitioners, updated toxicity information using the Toxicity Characteristic Leach Procedure (TCLP) is also necessary. Petitioners state that if EPA designates phosphogypsum and process wastewater as high-priority substances and conducts a risk evaluation, a Section 4 test rule will contribute to the development of information necessary to conduct the risk evaluation.

Petitioners claim that if EPA finds that their petition does not set forth sufficient facts to warrant initiation of prioritization, such a finding would only underscore the need for a Section 4 test rule. If EPA initiates prioritization but finds that the development of new information is necessary to make a final prioritization decision for phosphogypsum and process wastewater, Petitioners state that EPA should exercise its authority under Section 4 to obtain that information and establish priority.

Use of Phosphogypsum in Road Construction Is a Significant New Use

According to Petitioners, when EPA approved a request in October 2020 for the use of phosphogypsum in roads, it “reversed course on its 30+ years of finding that radon from phosphogypsum poses an unacceptable risk to public health if used in road construction.” Petitioners cite EPA’s 1992 National Emission Standards for Radon Emissions from Phosphogypsum Stacks and its “finding that ‘regardless of the radium-226 concentration, the use of phosphogypsum in road construction always resulted in a MIR [(maximum individual risk)] significantly greater than the presumptive safe level.’” EPA “determined that the use of phosphogypsum in road construction presents an unacceptable level of risk to public health.”


This petition appears to provide cogent arguments related to potential harm to health and the environment by phosphogypsum (a waste byproduct from the production of phosphate fertilizer) and related process water if both are not well managed. The petition also makes several arguments related to specific geographic locations. Without reviewing the facts underlying the various arguments in the petition, we cannot develop a view of the risk arguments or the data needs arguments. Assuming the risk arguments are valid, it is not clear that TSCA is the most efficient mechanism to address those risks. Neither phosphogypsum itself nor process wastewater is listed on the TSCA Inventory. It is likely that any commercial use of phosphogypsum is under the identity of calcium sulfate, in which other components (notably the toxic metals discussed in the petition) are considered impurities. EPA would have to prioritize calcium sulfate under Section 6, but not all calcium sulfate is from phosphogypsum, and not all calcium sulfate has the problematic impurities. Alternatively, EPA could prioritize phosphoric acid, perhaps as a category that includes phosphate salts, and evaluate as part of its manufacture condition of use the byproducts and wastes formed during manufacture and the associated disposal, including disposal of phosphogypsum and process wastewater. If EPA determined there to be unreasonable risk associated with disposal of the phosphoric acid production wastes, EPA could take action under TSCA to mitigate risks from disposal of such wastes. EPA could also employ one or more other EPA-administered authority (e.g., RCRA) if the risk could be eliminated or reduced to a sufficient extent under that authority. The Petitioners do seek a TSCA SNUR to prohibit use of phosphogypsum, but given the NESHAP decision to allow use of phosphogypsum in roadbeds, that use is likely ongoing, and EPA cannot issue a SNUR for an ongoing use (if the use is ongoing, it cannot be “new”).

The petition also requests that EPA take action under RCRA. In our view, RCRA is likely a more effective mechanism for addressing many of the risks identified in the petition because most of those risks relate to the management of disposal of the phosphoric acid production waste, as opposed to calcium sulfate itself. We note that certain of the Petitioners are parties to a suit dated December 18, 2020, challenging EPA’s October 20, 2020, approval of the use of phosphogypsum in roads and separately petitioned EPA on the same date to reconsider its decision to approve the use of phosphogypsum in roads. The Clean Water Act or Safe Drinking Water Act might also be effective at mitigating surface water or groundwater contamination from phosphogypsum.

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