There are two important caveats to the Guidance. First, as a guidance document, it is neither a rule nor a statement of policy. Second, the Guidance makes no attempt to establish a concentration level by which PFAS-containing material would need to be destroyed or disposed. It leaves the decision on when to destroy or dispose of such materials to existing applicable  regulatory mechanisms and guidance. Nevertheless, the Guidance provides instruction on the currently available methods for destroying or disposing of PFAS and PFAS-containing materials. 
 
As required under the NDAA, specific types of PFAS and PFAS-containing waste materials assessed in the Guidance include: (1) aqueous film forming foam (AFFF); (2) contaminated soil and biosolids; (3) non-consumer textiles treated with PFAS; (4) treatment materials such as spent filters, membranes, resins, and granular carbon; (5) landfill leachate containing PFAS; and (6) solid, liquid, or gas waste streams containing PFAS from facilities manufacturing or using PFAS.

The Guidance addresses a broad range of existing technologies available for the destruction and disposal of the specific types of PFAS and PFAS-containing waste materials, focusing primarily on (1) thermal treatment, (2) landfilling, and (3) underground injection technologies as the most effective in minimizing risk of environmental release.  The table below identifies the options available based on the phase of the waste:

Option 1: Thermal Destruction

While thermal destruction was associated with a relatively high degree of uncertainty for potential environmental release, the Guidance also cited existing hazardous waste combustion technologies (e.g., commercial incinerators, cement kilns, and lightweight aggregate kilns) as capable of achieving the highest level of potential for the control of releases. Scientific uncertainties associated with thermal destruction stem from EPA not having PFAS emission data from these sources when they burn PFAS.  EPA is working to develop measurement methodologies as well as continuing to gather information to assess whether potential products of incomplete combustion (“PICs”) are adequately controlled during thermal destruction.

The primary sources of potential PFAS emissions from thermal treatment are the stack emissions and subsequent management of scrubber water and bottom ash/fly ash. EPA plans to collect additional information and conduct research to better understand PFAS destruction and evaluate emission control efficiency. The current lack of a standardized validated methodology for measuring PFAS gaseous emissions makes consistent direct measurement of PFAS and potential PIC emissions not possible and limits understanding of combustion conditions under which relatively complete destruction of PFAS can occur. EPA also lacks detailed information on the amounts and concentrations of PFAS-containing materials that are generated and managed in thermal treatment devices. EPA expects to complete sufficient research to address the foregoing data gaps within 3 years.

Option 2: Landfill Disposal

According to the Guidance, hazardous waste or municipal solid waste landfills provide an available, feasible, and effective means of disposal for PFAS and PFAS-containing materials. While Subtitle C landfills possess the best technology for capture of leachate and landfill gas that may contain PFAS residuals, modern municipal solid waste landfills, when constructed with appropriate controls (e.g., liner system and leachate and gas collection and management systems), can also be employed to control the migration of PFAS into in the environment.

The key scientific uncertainties associated with landfill disposal options include that, even with appropriate controls in place, releases from landfill gas and leachate can result in PFAS off-site migration because little is currently known about PFAS behavior in landfills.  EPA believes that additional research is needed on the effects of PFAS on liner integrity, gaseous emissions from landfills, the effectiveness of leachate treatment for PFAS removal, and the levels and types of PFAs. 

Option 3: Injection

Class I deep well injection is a feasible and effective disposal option with a low level of uncertainty associated with the migration of PFAS into the environment. However, given the limited number of wells currently receiving PFAS, EPA concludes that the potential for additional waste transportation costs may significantly limit the practicability of deep well injection as a disposal option.

The Guidance prioritizes technologies according to their level of scientific uncertainty in measuring and controlling environmental releases of PFAS, listing them in order of lowest uncertainty to highest as follows:

1. Interim storage for 2 to 5 years pending additional research to reduce uncertainties associated with other options.

2. Permitted Class I deep well injection (liquid waste only)—Option 3 above.

3. Permitted hazardous waste landfills (RCRA Subtitle C)—Option 2 above.

4. Solid waste landfills (RCRA Subtitle D) with composite liners and leachate collection and treatment systems)—Option 2 above.

5. Hazardous waste combustion, including commercial incinerators, cement kilns, and lightweight aggregate kilns—Option 1 above.

6. Other forms of thermal treatment, including carbon reactivation units, sewage sludge incinerators, municipal waste combustors, and thermal oxidizers—Option 1 above.

The Guidance also includes comparisons of costs associated with each technology and identifies existing data gaps contributing to scientific uncertainties associated the propensity for releases for each technology. In addition, as required under the NDAA, the Guidance assesses the potential for adverse impacts on potentially vulnerable populations living near likely destruction or disposal sites, and provides guidance on testing and monitoring air, effluent, and soil near potential destruction or disposal sites.

The EPA plans to review this Guidance every 3 years and to revise it if EPA deems appropriate based on new information or other factors.