For decades, the inactive sulfur mine, located in Alpine County, California five miles east of Markleeville, has released acid mine drainage into Leviathan Creek, Aspen Creek, Bryant Creek and the east fork of the Carson River - a major source of water and a habitat for fish.
Until a final cleanup plan is developed, seasonal treatment of acid mine drainage is necessary to prevent untreated releases of elevated concentrations of arsenic, iron, aluminum, chromium, cobalt, copper, nickel and zinc. Pollution draining from the site has destroyed most aquatic life in Leviathan Creek and portions of Bryant Creek downstream of the mine.
Under the $8 million settlement agreement between the U.S. Environmental Protection Agency and Atlantic Richfield, the company has agreed to treat acid mine drainage for five years at a cost the EPA estimates at $5.6 million.
The company also will reimburse the EPA for $1.7 million in past cleanup costs and pay $90,000 in penalties for failing to comply with an EPA order issued in 2000.
Sign at the Leviathan Superfund site (Photo credit unknown)
Additionally, the company will spend $400,000 on a riparian restoration project at the River Fork Ranch on the Carson River, near Genoa, Nevada.
"Today's agreement addresses the most significant pollution from the mine and protects Leviathan Creek until a long-term cleanup strategy is in place," said Keith Takata, the Superfund Division director the EPA's Pacific Southwest region.
Under EPA oversight, the company will treat acid mine drainage from several sources at the mine from June 1 to September 30. The treatment season will be extended before the final cleanup is selected, if conditions at this remote mountain site allow safe access and operation.
Because the site lacks paved roads and power lines, winter treatment of most seeps will not be accomplished through interim actions, although biological treatment technology will continue to be used at one of the seeps at the site through the winter.
"This settlement makes sure that the company that caused the pollution pays for the cleanup and restores vital habitat downstream from the site," Takata said.
Listed as a Superfund site in 2000, the site was initially developed as an underground mine for gold, copper and copper sulfate, starting in 1863.
From 1954 through 1962, the Anaconda Copper Mining Company, which later was acquired by Atlantic Richfield, conducted open pit mining. The open-pit mining of sulfur from the site left wastes and underground conduits that result in acid mine drainage.
In 1984, the state of California acquired 495 acres of the mine to clean up and abate water quality problems. The Lahontan Regional Water Quality Control Board, which was delegated authority over the mine property, constructed evaporation ponds in an attempt to reduce the impact from some of the mine releases.
Since 1999, the water board has treated drainage collected in these ponds, to prevent overflow into Leviathan Creek. This work, together with seasonal treatment conducted by Atlantic Richfield since 2001, has improved conditions for aquatic life when the systems are operating.
The new settlement complements a separate EPA order issued in June 2008 requiring Atlantic Richfield to investigate long-term cleanup methods for the site, from which the EPA will select.
The agency anticipates that Atlantic Richfield, the state of California, the Washoe Tribe of Nevada and California, and other stakeholders will enter into negotiations to implement final cleanup by 2013.
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