PFAS within Landfills, Leachate and Generic Wastes
Only a small contingent of states have promulgated drinking water maximum contaminant level (MCL) standards for per- and polyfluoroalkyl substances (PFAS) below the federal advisory of 70-parts per-trillion (ppt). And yet, a growing number of state agencies are actively sampling for PFAS to determine their occurrence, levels and potential environmental pathways. The California State Water Resources Control Board (CSWRCB) has been actively investigating and sampling for PFAS since 2019, and many experts believe new MCL standard(s) are forthcoming for drinking water and potentially for biosolids and waste streams.
California state officials are sampling for PFAS in phases, concentrating on sites they suspect have been impacted the most. Phase one includes airports and landfills, which represent two of the likeliest depositories for these resilient compounds. Airports were easy targets because of their historical use of aqueous film forming foams (AFFFs), which intrinsically contain PFAS, while landfills represent the end-point for PFAS-containing products like furniture, textiles and carpeting. In this edition of Breaking Down PFAS, we will look closer at landfills and why they serve as important battlegrounds in the fight against PFAS.
There are an estimated 4,700 PFAS used globally for industrial, business and personal uses, making them difficult to track. With the potential to release PFAS into the environment via infiltration, surface runoff, leachate, evaporation or off-gas emission, landfills are useful vantage points to study these pervasive chemicals. Visit any municipal landfill, and you will likely run across shampoo bottles, non-stick pans, fast-food packaging and scores of other PFAS-laden waste. In some cases, PFAS can migrate into the soil and or surface water and groundwater. The fate of PFAS within landfills is controlled by a combination of biological and abiotic processes.
“The factors influencing fate and transport of PFAS within landfilled wastes and their migration outside the landfill containments can change dramatically over time,” says Raj Vaidya, an environmental engineer at CDM Smith and an expert in the management and treatment of landfill leachate.
Further complicating sampling and treatment, Vaidya says, is the presence of PFAA precursors within the leachate, such as fluorotelomer carboxylates (FTCAs). Recent studies have shown that landfill leachates may contain precursors, which can be converted into persistent and non-biodegradable perfluoroalkyl acids (PFAAs) in the environment or during wastewater treatment processes. Through oxidation, FTCA compounds can transform into perfluoroalkyl carboxylates (PFCAs, e.g. PFOA and PFHxA), associated with potential health effects. This can happen through microbial activities or chemical oxidation, processes associated with conventional wastewater treatment, as well as within natural systems. That means that traditional treatment processes actually have the potential to convert these precursors into more toxic and persistent PFAAs. In some cases, researchers have discovered higher concentrations of PFAS in treated leachate than in its raw state.
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- Publicly-owned treatment works (POTWs) may set more stringent restrictions on leachate acceptance.
- Environmental liability will likely increase for landfill leachate.
- Leachate collection/management systems may be impacted.
- Data accuracy—no EPA approved method for analysis of PFAS in leachate at this time.
- Traditional leachate treatment technologies may not work for targeted PFAS removal.
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The significant amount of PFAS observed and or suspected within landfills has led to increased concern over leachate management. In Vermont, statewide studies discovered PFAS in both lined and unlined landfills. “PFAS in landfill leachate is pervasive and has been detected at significant concentrations with respect to the EPA guideline of 70 ppt, with the potential for adverse environmental impacts,” reads a report from the state Agency of Natural Resources. Similar studies are underway in Michigan, New Hampshire, New York and California. EPA has recently awarded projects to identify source, occurrence, transformation and treatment of PFAS within wastewater and biosolids.
Currently, EPA has not approved a standardized sampling method for landfill leachate, making it hard to replicate studies for the purpose of risk analysis. EPA and private research efforts continue to develop and validate ways to quantify PFAS in the non-potable water matrices, including landfill leachate. Commercial laboratories have even included certain FTCA precursors in their PFAS analyte suites, which experts believe will help us understand PFAS compositions and behaviors in landfill leachate.
I envision more landfills will be requiring formal investigative programs.
The current phase of California’s sampling initiative focuses on wastewater treatment plants, another critical stop on the PFAS trail. Beginning this October, publicly-owned treatment works (POTWs) will be required to sample and analyze influent and effluent, as well as reverse osmosis concentrate, for dozens of specified PFAS. And while California has not yet released an MCL for any specific PFAS, the state recently lowered its response levels from 70 ppt to 10 ppt for PFOA and 40 ppt for PFOS. As PFAS in excess of the response levels is found in water supply wells, the water treatment facility will either have to notify customers, provide treatment or possibly shut down the affected source.
Breaking Down PFAS will be providing ongoing coverage of these state-by-state sampling efforts. For more information on what is happening in your area, reach out to one of our PFAS experts below.