In 2018, the EPA issued the first of two sets of amendments to the Agency’s 2015 regulations (April 17, 2015, Federal Register (FR)) governing the disposal of coal combustion residuals (CCR) generated by electric power plants. Among other things, the 2015 rule directed that the owners and operators (O/O) of CCR units (i.e., landfills and surface impoundments) install a groundwater monitoring system. The O/O would need to dig monitoring wells and specify how they would draw samples from the wells, analyze the samples to detect the presence of hazardous constituents from the CCR unit, and then take corrective action to control the releases. The monitoring requirements applied to all CCR units; the EPA offered no exemptions or alternatives.
That changed in 2018 when the EPA’s amendments (July 30, 2018, FR) included a waiver from the groundwater monitoring provisions. As it now stands, the Agency is allowing states with approved CCR permitting programs to suspend groundwater monitoring if the O/O can demonstrate that there is no potential for migration of any CCR constituents to the uppermost aquifer during the active life of the unit, closure, and post-closure care. Release from the requirement is effective for a period of 10 years and is renewable.
Geology Is a Factor
The Agency provided two reasons for relaxing the monitoring requirements.
- First, suspension of groundwater monitoring requirements based on a no-migration demonstration has been a component of both the 40 CFR Part 258 (municipal solid waste landfills) and the RCRA Subtitle C (hazardous waste) groundwater monitoring programs for many years. Based on this experience, the Agency said it expected that cases where the no-migration criteria are met will be rare.
- Second, the Agency says that certain hydrogeologic settings may preclude the migration of hazardous constituents from CCR disposal units to groundwater resources. Requiring groundwater monitoring in these settings would provide little or no additional protection to human health and the environment.
Provisions O/Os must meet to have their monitoring requirements suspended are listed at 40 CFR 257.90(g) and summarized as follows:
- Site-specific field-collected measurements, sampling, and analysis of physical, chemical, and biological processes affecting contaminant fate and transport must be conducted and include the information necessary to evaluate or interpret the effects of the following properties or processes on contaminant fate and transport:
- Aquifer characteristics, including hydraulic conductivity, hydraulic gradient, effective porosity, aquifer thickness, degree of saturation, stratigraphy, degree of fracturing and secondary porosity of soils and bedrock, aquifer heterogeneity, groundwater discharge, and groundwater recharge.
- Waste characteristics, including quantity, type, and origin.
- Climatic conditions, including annual precipitation and effects on leachate quality.
- Leachate characteristics, including composition, solubility, and density.
- Engineered controls, including liners, cover systems, and aquifer controls (e.g.,lowering the water table).
- Contaminant fate and transport predictions that maximize contaminant migration must be made.
- The no-migration documentation must be certified by a qualified professional engineer and approved by the participating state director or the EPA where the EPA is the permitting authority.
- The specific details of any suspension of groundwater monitoring because a no-migration demonstration has been made must be posted to the facility’s public website.
Evidence of Experience
One question that has been asked about the provision that allows the suspension of groundwater monitoring requirements based on a no-migration demonstration is why the Agency included it at all. As noted, the EPA says that based on its experience with similar provisions for municipal solid waste programs and hazardous waste landfills, it expects that cases where the no-migration criteria are met will be rare.
In comments on the proposal, a coalition of environmental groups noted that while the waiver from monitoring for hazardous waste landfills was granted over 30 years ago, in its proposal (and in the final revisions) the Agency “provides no evidence in the record of any kind pertaining to the ‘no-migration’ waiver.”
“Despite the decades-long presence of this waiver for both hazardous waste facilities and municipal solid waste landfills, EPA produces no evidence of the granting or denial of groundwater monitoring waivers by state officials or evidence of the conditions at sites where waivers were denied or granted,” the groups continued. “While EPA states in its proposal that ‘based on its experience under these programs, the Agency expects that cases where these criteria are met will be rare,’ EPA shares no specific ‘experiences’ in the proposal. In failing to do so, EPA has not provided any rational basis to apply the ‘no migration’ waiver to CCR units and to demonstrate that states have not abused their authority to grant such waivers.”