The private company behind efforts to capture and clean landfill emissions into natural gas at the Ada County Landfill says it is weeks away from delivering fuel to Intermountain Gas customers.
Boise State Public Radio first reported on the project in January, now a group of citizens is questioning the safety of that gas.
“For a long time, people thought mostly about PFAS leaving landfills in what's known as the leachate, the liquid that percolates through a landfill. But it also turns out that quite a lot of it can leave in the gas,” said Richard Llewellyn, northwest Boise resident and part of Citizens Allied for Integrity and Accountability (CAIA).
The more-than decade old group advocates for public health, clean air and water.
The effects of PFAS on humans aren’t fully understood, but the so-called "forever chemicals" have been linked to multiple health problems. PFAS, widely used for decades in manufacturing, don’t break down like other chemicals do and are considered toxic.
CAIA points to a 2024 study of landfill gas emissions done at the University of Florida, which showed significantly higher PFAS emissions in landfill gas compared to previous studies.
But those studies tested untreated gas emissions, not a pipeline-quality renewable natural gas like Texas-based BioGas will produce. BioGas, working locally as Hidden Hollow Energy, LLC, built a processing facility at the Ada County Landfill which converts captured landfill emissions through multiple stages of pressure and temperature changes, and filtration.
Hazardous and other chemicals are separated and disposed of (some get incinerated) and climate-warming methane is captured before it can damage the environment. The project can serve thousands of homes and businesses with gas that would otherwise just be flared off at the landfill.
BioGas CEO Ahren Tryon wrote in a letter to CAIA that the company is trying to find a way to monitor potential PFAS levels, but the science is so new sampling protocols don’t exist.
“We have spoken with several labs, all of whom have told us that they are not willing or able to do testing given the absence of industry-standard sampling protocols and methodologies, the complexity of the gas matrix, and the difficulty in detecting the thousands of types of PFAS,” he wrote.
Tryon’s letter referenced other research showing PFAS concentrations in landfill leachate are significantly less than the direct exposure humans get from food, carpet or dust, and noted that the University of Florida study was an outlier, with very different results than other studies. BioGas has attempted to reach that study’s authors to get more information, but the teams have not yet been able to meet.
BioGas expects its filtration process to keep PFAS out of the finished natural gas, but said it will continue to work toward PFAS monitoring. It said it is already following the best-known practices for PFAS mitigation.
Pressure and temperature "beds," and activated carbon towers, “work in tandem to remove any PFAS, VOCs [volatile organic compounds] and other contaminants remaining in the gaseous phase,” BioGas wrote.
“These contaminants are swept to a thermal oxidizer for high heat incineration, as is the practice in the water sector for PFAS remediation under EPA regulations,” Tryon wrote.
CAIA does not oppose the landfill gas capture project - they really like it, Llewellyn said. The group’s President, Shelley Brock, said by phone the potential danger of PFAS in people’s homes is too great to ignore. She said the litigation risk is significant if the renewable natural gas is shown to carry PFAS after delivery to utility customers begins.
At a public information meeting at Avimor March 30, some attendees said they didn’t want to be "guinea pigs" for the project, Brock said. She said Intermountain Gas has told CAIA that the renewable natural gas (RNG) is mostly likely to reach customers in Avimor, Hidden Springs and some northwest Boise neighborhoods. Those areas are closest to where the RNG will enter the utility pipeline.
Other community meeting attendees called the project beneficial, as long as the proper risk mitigation is in place, according to BioGas’s local spokesperson Brian Cronin.
Llewellyn said BioGas should test what it can right now to determine PFAS levels at the Ada County Landfill, but Cronin said testing leachate as the group suggested wouldn’t provide any relevant information to what might be in the treated gas.
Tryon wrote that BioGas is committed to finding a partner for PFAS monitoring and to work together with researchers and regulators to develop testing protocols.
But the company is not going to wait. Cronin said the Hidden Hollow Renewable Natural Gas project has received its "blessing" from Ada County and Intermountain Gas to begin full operations by next month. A ribbon-cutting on the new facility is planned in mid-May.
