STANISLAUS COUNTY — Stanislaus County will expand efforts to contain a toxic underground plume that slowly spreads from the former Geer Road landfill.
An April 2011 state order required the county to show where the plume has spread and prepare a more vigorous cleanup plan so the contamination does not taint the nearby Tuolumne River or creep closer to Hughson.
Tests showed the plume has spread underneath the Tuolumne, although contamination has not been detected on the river's west side.
Jami Aggers, interim director of environmental resources, said the reports and cleanup proposals were sent to the state by the Dec. 31 deadline. The Central Valley Regional Water Quality Control Board could notify the county within 30 to 60 days whether the plan is approved.
The plan, developed with the help of consultants, calls for 20 more wells to remove and burn gas that is emitted into the soil by rotting garbage. The groundwater cleanup system would expand from 11 extraction wells to 25. Water pumped from the ground is filtered to remove contaminants and then injected into leaching beds.
Expanding the two systems is estimated to cost about $2 million, Aggers said. The money will come from a Geer Road landfill cleanup fund, which is fed by disposal fees at the Fink Road landfill.
"What we are required to do is contain the plume," Aggers said. "I am very confident with the recommendations the consultants came up with. We need to keep it localized."
The 168-acre dump on Geer Road, about a mile northeast of Hughson, accepted garbage from 1970 to early 1991, when it was closed after tests on nearby wells showed contamination. About 4.5 million tons of garbage was buried in huge holes dug not far from the river, with no bottom liner to keep toxic substances out of the groundwater.
Tests show the plume is tainted with volatile organic compounds including vinyl chloride, 1,2-dichloroethane and Dichlorodifluoreo-methane. Other toxins are detected at amounts far exceeding state limits.
The county has spent millions of dollars on cleanup efforts and paid almost $2.2 million resolving lawsuits from neighbors whose wells were polluted.
Bee staff writer Ken Carlson can be reached at email@example.com or (209) 578-2321.