A worker installing a passive soil gas sampler on November 19.
Quick actions taken to control contamination resulting from recent cleanup activities at the Pasco Landfill property have effectively stopped chemicals from moving into groundwater.
In November 2024, we reported increased contamination was found in monitoring wells near the cleanup site’s Zone A. Thermal treatment of contaminated soil began at this site earlier this year after the successful removal and disposal of over 35,000 drums of industrial waste.
The project team installed soil gas samplers where groundwater contamination was recently increasing to monitor for vapor intrusion. This is when contaminant levels in groundwater could cause unsafe levels of contaminants to build up indoors. These soil gas samplers remained in the ground for about 12 days to collect data and were sent to a laboratory for testing after they were retrieved. The samples from early December showed groundwater does not pose a risk to air quality in nearby buildings.
Ecology and the parties responsible for cleanup will continue to monitor groundwater every three weeks to ensure off-property contaminant levels remain stable. As required by the legal order amendment, the project team is working diligently to design a groundwater treatment system that will start up in early 2025 to ensure contamination does not move away from the Pasco Landfill property.
A public comment period on the documents we created to guide the current activities continues until January 20, 2025.