Another fire may be smoldering underground at a landfill just east of Pasco city limits.
New evidence has been found of burning waste and groundwater contamination where 35,000 drums of solvent, plus paint sludges and cleaner, are buried, according to the Washington Department of Ecology.
A fire in a different area of the Pasco Sanitary Landfill burned for two years starting in late 2013 before efforts to put it out worked.
The new fire does not pose an immediate threat to the Tri-Cities, according to the Department of Ecology. Regional emergency response agencies are aware of the situation.
The 250-acre landfill near the intersection of Kahlotus Road and Highway 12 is a federal Superfund site that is no longer used for disposal.
During the past year, elevated temperatures were noticed in the area called Zone A.
A borehole was used to bring up charred waste. It’s unknown whether the underground waste is continuing to smolder.
The waste is at least 15 to 20 feet below ground. The area was topped with a thick cover of sand, soil, clay and plastic in 2001, according to Ecology.
Sampling done in June at a Zone A groundwater monitoring well have added to Ecology’s concerns.
The department found a three-inch thick layer of petroleum hydrocarbons, solvents and polychlorinated biphenyls, or PCBs, floating on the groundwater. Sampling of other wells just outside Zone A did not find similar floating contamination.
The condition of the drums in Zone A is not known, but the groundwater contamination appears to show that previously intact drums are leaking, said Ericka Bronson, a Department of Ecology spokeswoman.
The parties that are potentially responsible for the landfill are monitoring and sampling contamination under state supervision.
A recent state mailing to residents in the area said the likely source and extent of the contamination will be determined to help prevent further contamination.
Ongoing cleanup efforts have improved groundwater quality outside the landfill and shrunk the contaminated groundwater plume.
The city of Pasco restricts groundwater use in areas previously contaminated by the landfill.
The previous underground fire was burning in a nearby area where bales of household and municipal waste, and construction debris, were buried until 1989.
It was finally put out by digging a deep trench around the smoldering waste and filling it with soil and concrete to create a barrier to prevent the fire from spreading.
Then pockets of smoldering waste were dug up and mixed with a slurry of water, clay and cement.
Those potentially liable for the cleanup of the landfill include companies such as Du Pont, Boeing, Union Oil of California and Basin Disposal, and government entities such as Franklin County and the Air Force.
In late August, the parties submitted a revised draft study that compares cleanup options for the entire landfill. After a Department of Ecology review, it will be released for public comment.
The state agency will use public input as it writes a cleanup plan, which also will be released for public comment, it said.