The department is collecting comments on the cleanup action plan through Oct. 3, with a public meeting scheduled for 6:30 pm, Sept. 17, at Robinson Elementary in Pasco.
While the 200-acre landfill was used for a variety of household and commercial waste from the 1950s to 2001, it was also used to store thousands of barrels of industrial and agricultural waste deposited there in the early 1970s.
Various chemicals from the site have leached into groundwater and surrounding soil and some have contaminated the air as materials in the landfill decompose. Some have leaked from containers.
For decades, Ecology, the city of Pasco and other local governments have been working with potentially liable parties to work on cleaning up the contamination.
Herbicide-manufacturing waste that was stored in about 5,000 55-gallon drums was removed in 2002, and other cleanup work has included removing about 1 million pounds of contamination from the soil and capping the site.
After a 2013 underground fire at the site, and continued monitoring of groundwater contamination, Ecology now wants to remove 35,000 drums of industrial waste due to concerns about higher temperatures and continued risk of contamination.
About 3 inches of liquid waste has leaked out of those drums and is floating on the water table, including chemicals such as petroleum hydrocarbons, solvents and PCBs (polychlorinated biphenyls), according to Ecology.
Once they're uncovered, the plan is to separate the industrial waste drums by contaminant type and send them to appropriate waste sites.
The household and commercial waste on site is set to be left in place, and gases from the decomposition there will continue to be collected and flared off.
Potentially liable parties either have to sign onto a consent decree agreeing to the cleanup or they'll receive enforcement orders from Ecology.
Comments on the cleanup plan and legal documents can be submitted online or sent to email@example.com.