PASCO — A fire burning underground at the long-closed Pasco Sanitary Landfill will be starved of oxygen to extinguish it, according to the Washington State Department of Ecology.
The 250-acre landfill, just east of city limits at Dietrich Road and Commercial, is a federal Superfund site.
The fire is burning in an area where bales of household and other municipal waste and construction debris were buried until 1989. But it is adjacent to an area of greater concern, where an estimated 35,000 drums of solvent and paint sludges, cleaners and other waste were buried.
“There is no immediate threat to people living near the site, local businesses or site workers based on our current knowledge,” said Mike Hibbler, regional manager of the state’s Toxics Cleanup Program, in a statement.
The area that is burning appears to be small, measuring about 25 feet in diameter, according to the state. Environmental cleanup workers noticed the ground had sunk almost two feet there and notified the state. Wisps of smoke also were seen coming from cracks in the soil.
Ecology workers took a look at the depression Dec. 2 and the next day, carbon monoxide tests confirmed that a fire was smoldering beneath the ground, said Ecology spokeswoman Brook Beeler.
A decision on how to address the fire was made after a joint visit Monday with representatives of companies liable for environmental cleanup at the landfill and local agencies, including Franklin County Emergency Management, Franklin Fire District 3 and the Pasco Fire Department, Beeler said.
Work started with a long-arm trackhoe to pile about two feet of soil on the ground above the burn, filling in cracks that allow oxygen to feed the fire, she said.
In addition, the operation of a vapor extraction system to vacuum contaminated air at the adjacent industrial dumping area has been modified as an immediate step to make sure gases are not being sucked across the burning area to feed the fire, Beeler said.
The system has three wells that act as straws to draw air contaminated with volatile organic compounds out of the ground, she said. Two of the wells are at depths that could affect the fire in the adjacent area for baled municipal waste.
It’s uncertain how long the fire could continue to burn underground and monitoring is planned to make sure it does not spread. Additional temperature readings are being taken to more accurately map its extent.
The state is developing a plan to continue to monitor for carbon monoxide and other potentially harmful gases, such as methane, Beeler said.
Decisions also are being made on how to monitor the vacuum system being used for environmental cleanup to prevent a buildup of gases as operating procedures are changed.
People who live within two miles of the landfill have been mailed a letter with information, she said.
The landfill also has other municipal and industrial waste areas. In addition to the 35,000 drums, the waste includes about 11,000 tons of sludge from paper manufacturing and residues from the disposal of 3 million gallons of plywood resin waste, lime sludge and bulk liquid waste.
Almost 5,000 drums of herbicide manufacturing waste was removed in 2002. Last summer the major work was finished on a new cover to prevent water from infiltrating the contaminated soil left from the drums.
The landfill has contaminated a plume of groundwater more than two miles long. The cigar-shaped plume stretches from the landfill past A Street toward the Columbia River. Treatment systems are being used to reduce the level of contamination in the groundwater.