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Release Date: 11/22/2000
Contact Information: Leo Kay, U.S. EPA,Press Office, 415/744-2201

     SAN FRANCISCO   The U.S. Environmental Protection Agency issued an administrative order to ARCO today to address acid mine drainage sources at the Leviathan Mine Superfund Site outside of Markleeville, Calif. that have not already been fully addressed by the Lahontan Regional Water Quality Control Board.

     The order also directs ARCO to review the regional board's site database and to collect additional information needed to determine a long-term cleanup plan.

     "This order will continue to allow us to address short-term solutions for Leviathan while we work toward a long-term cleanup plan," said Keith Takata, director of the EPA's Superfund program in San Francisco.  "The regional board did a great job at performing stop-gap work this past summer.  Now it's ARCO's turn."

     The work required under this order incorporates knowledge gained through the regional board's efforts at the site this past summer.  During the 2000 construction season, the regional board treated enough acid mine drainage 13 million gallons to nearly eliminate the potential for pond overflow in 2001, and also collected information on treatment processes, streamflow and water quality in the streams.  Board members also upgraded site fences and roads, revegetated much of the site to lessen future runoff, and monitored flow and water quality.

     The four major components of the order being issued to ARCO are:

          ARCO is required to produce a site management plan that provides a framework and schedule for accomplishing both short-term and long-term goals;

          ARCO must provide a plan for capturing the remaining untreated sources of acid mine drainage, then implementing the plan starting in 2001.  Although between 10 and 20 million gallons of acid mine drainage is captured in the ponds each year, it is estimated that another 25 million gallons per year of less acidic drainage flows into Leviathan Creek. (Acid mine drainage forms when rainfall and snowmelt mixes with the sulfur-bearing mine waste. This acid in turn dissolves metals, including arsenic from the waste rock, before flowing into Leviathan Creek.);

          ARCO must compile all existing data   as well as collect new information   on the mine and the watershed to understand the effectiveness of the early actions. ARCO will also collect much of the new information necessary for a clear understanding of site conditions and downstream effects;

          ARCO is required to produce a second phase of data collection and interpretation that will lead to a long-term plan.  The second phase will to take into account the site conditions as they have been improved by the early response actions.  Engineering design information will also be included at this stage to develop feasible long-term cleanup options.

     The EPA expects the short-term response to be implemented over the next two or three years, with a  long-term cleanup plan to be developed the following year. The EPA designated the Leviathan Mine as a federal Superfund site in May.