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U.S. EPA selects plan to clean up part of the Lava Cap Superfund Site in Northern California

Release Date: 9/29/2004
Contact Information: Laura Gentile (gentile.laura@epa.gov) - 415/947-4227 (desk) or 415/760-9161 (cell)

SAN FRANCISCO - -Today the U.S. Environmental Protection Agency selected a plan to clean up environmental contamination resulting from mining operations at part of the Lava Cap Mine Superfund Site, located in Nevada County, Calif.

The cleanup plan will address contamination of water and soil from arsenic and other heavy metals, which are byproducts of historic mining operations. The plan includes cleaning up mine tailings and waste rock, collecting and treating contaminated water from the mine, and diverting the flow of clean surface water around contaminated tailings.

"This remedy will take care of the most significant contamination posed by the Lava Cap Mine," said Keith Takata, director of the Superfund division for the EPA's Pacific Southwest region. "The plan outlines a comprehensive cleanup strategy for the mining area, local residences and Little Clipper Creek."

The mine, which operated from 1861 to 1943, used cyanide to extract gold from ore that contained naturally occurring arsenic. The waste materials, or tailings, were deposited in an adjacent stream channel behind a log dam.

During a storm in the late 1990s, the upper half of the log dam collapsed, sending more than 10,000 cubic yards of arsenic-contaminated tailings into the creek. One year later, most of the tailings had been moved out of the creek and drainage in the creek had improved.

Arsenic in the mine tailings could cause health problems in humans and pets through inhalation or ingestion. Young children are more at risk than adults from exposure to arsenic. Depending on the total amount taken in by the body over time, health effects that may result from arsenic exposure could include skin changes, damage to organs and even death.

The EPA presented its proposed cleanup plan to the public for comment in February.

The EPA continues to investigate extensive tailings that were deposited downstream at Lost Lake, as well as possible groundwater impacts from the mine. The EPA may propose further cleanup actions at a later date.

The Lava Cap Mine site was placed on the Superfund National Priorities List in February 1999. The NPL is the EPA's list of hazardous waste sites potentially posing the greatest long-term threat to public health and the environment.