Decades after industrial dry cleaning solvents first seeped into the ground beneath downtown Billings, federal environmental crews are drilling through basement floors to measure toxic chemical vapors inside local properties. The Environmental Protection Agency is expanding its investigation into the Billings PCE Superfund site, identifying 81 more buildings to test as a long-standing chemical plume continues to migrate northeast.
The contamination stems from a former dry cleaning operation that used PCE and TCE. While the EPA dug out 3,600 tons of contaminated dirt at the source on 715 Central Avenue roughly twenty years ago, the underground plume never fully vanished.
Drilling Beneath Downtown Billings
Inside local buildings, contractors are installing small testing ports directly beneath concrete foundations. These devices capture gases accumulating in the subsurface soil, functioning much like standard residential radon mitigation systems. Contaminated groundwater carries the dissolved chemicals beneath structures, where the vapors find entry routes through cracks in concrete, utility conduits, or basement walls.
“It’ll pull the gasses that accumulate under the building, very similar to radon,” said Roger Hoogerheide, EPA remedial project manager for the Billings PCE Superfund site.
The EPA plans to deploy a Trace Atmospheric Gas Analyzer (TAGA) mobile laboratory next week to measure vapor concentrations across the expanded testing zone. The current sweep covers an area stretching from Central Avenue near 7th Street West straight into downtown Billings. Earlier this year, in June, the agency announced plans to install radon-style mitigation systems in 400 homes threatened by the migrating plume.
Property Owners Weigh In
The testing zone encompasses diverse downtown properties, including historic landmarks and active commercial spaces.
“You can’t change what’s happened already, so right now all you can do is move forward and try and make sure that the community is safe,” said Aly Turner, executive director of the Moss Mansion, which is among the 81 newly identified buildings slated for vapor testing. “And that’s what they’re doing by doing this testing.”
Not all downtown properties register active vapor intrusion. Adjacent to the primary contamination zone, some commercial structures have consistently recorded clean indoor air metrics over years of regular monitoring.
“We’ve had several tests over the years that show we have a clean bill of health for as far as air quality inside the building from the EPA,” said Bryan Gentry, a property manager working next door to the original contamination site.
Federal officials acknowledge that the source property itself requires additional intervention. Unsafe chemical levels persist at 715 Central Avenue, prompting environmental regulators to formulate long-term remediation milestones.
“I anticipate that we will probably issue a cleanup document, if not next year, then it will probably be in 2028,” Hoogerheide said.
For now, field crews are focused on completing the round of building assessments to determine which commercial and historic structures require immediate vapor mitigation systems.
