Two different plans for putting out the fire burning underground at the Pasco Sanitary Landfill have been submitted to the state of Washington by the 32 parties potentially liable for the cleanup.
"There are perhaps different views and opinions on the best approach to put the fire out," said Chuck Gruenenfelder, state Department of Ecology site manager.
"Ecology wants to get at it in an aggressive manner," he said.
The Department of Ecology ordered the parties to submit a plan by this week to promptly put the fire out after it had burned from November through April. It has continued to burn since then, remaining at a little more than 25 feet in diameter.
In December, soil was piled on the ground as deep as two feet above the burn in some places to help prevent oxygen from feeding the fire. The operation of a vapor extraction system to vacuum contaminated air at the adjacent industrial dumping area was modified to make sure gases are not sucked across the burning area to feed the fire.
One subgroup of the parties potentially responsible for the closed landfill is proposing a three-pronged approach.
An engineered cap would be placed over the burning area to further reduce the possibility of oxygen getting through cracks in the ground to feed the fire. The cap would include a heavy plastic layer covered with more dirt.
More monitoring stations also are proposed.
Probes in the ground already are measuring heat in the area of the fire to give three-dimensional information on where it is burning.
More probes would be added to measure temperature and the pressure of gas underground. They could provide information on how the vapor extraction system may continue to influence the fire, Gruenenfelder said. The number, location and depth of the possible additional probes have not been determined.
The proposal also provides for injecting carbon dioxide at low concentrations into the ground to displace any oxygen. It's a gas commonly used for extinguishing underground fires, Gruenenfelder said.
The alternate proposal by different parties calls for placing more soil over the fire and perhaps modifying the vapor extraction system.
The proposals do not include a full list of parties backing each, or both. Franklin County is backing the second plan, which would not include a plastic cap or injection of carbon dioxide, Gruenenfelder said.
The landfill is northeast of Pasco near the intersection of Kahlotus Road and Highway 12. Franklin County is the only local government named as a possible responsible party for the cleanup. Others on the list include businesses and federal government agencies.
The fire is burning in an area of the landfill where bales of household and other municipal waste and construction debris were buried before 1989. The state is concerned that as the fire continues to burn it poses a potential threat to a part of the landfill where 35,000 drums of solvent and paint sludges, cleaners and other industrial waste are buried.
The closed landfill is a federal Superfund site.
The coalition of responsible parties also will be required to install a fire monitoring network and develop a plan to minimize the potential for future underground fires.
The state will continue to discuss the two proposals with the parties through May and also will accept public comment until May 29. Comments may be emailed to email@example.com or mailed to Chuck Gruenenfelder, Department of Ecology, 4601 N. Monroe St., Spokane, WA 99205-1295.
-- Annette Cary: 582-1533; firstname.lastname@example.org; Twitter: @HanfordNews