Department of Justice Seal Department of Justice
MONDAY, MARCH 25, 2002
DOJ: (202) 517-2007
TDD: (202) 514-2008
EPA: (303) 312-6780
EPA: (202) 564-7818


Settlement Addresses Nation’S Largest Body Of Contaminated Water

WASHINGTON- The Justice Department, the Environmental Protection Agency and the state of Montana today announced an $87 million settlement with Atlantic Richfield Company (ARCO), a subsidiary of BP p.l.c., and five other mining companies to control billions of gallons of highly acidic mine drainage that is contaminating the Berkeley Pit in Butte, Mont. The agreed on remedy will prevent the mine drainage, which is filled with arsenic and heavy metals, from flowing out of the pit and endangering Butte’s drinking water supply, Silver Bow Creek and the Clark Fork River.

The Berkeley Pit is part of the Silver Bow Creek/Butte area Superfund site located in the Clark Fork Basin in southwestern Montana, and total costs of cleanup and control at the pit alone will likely reach $110 million. The remedy will be performed by ARCO and five other settling defendants -- ASARCO, AR Montana Corporation, Dennis Washington, Montana Resources, and Montana Resources, Inc..

Under the agreement, the settling defendants will pump and treat the pit’s highly acidic mine water, which now amounts to over 30 billion gallons, to maintain the water below a critical level. Absent EPA’s cleanup action, contaminated water from the pit would flow into Silver Bow Creek and area groundwater, polluting those bodies of water, and thereby endangering any persons relying on that water for drinking water and the fish population.

The Berkeley Pit site encompasses roughly 23 square miles near downtown Butte. Surrounding the Berkeley Pit are more than 3,500 miles of underground mine workings that were operated by several separate mines since 1865. Until 1982, all of these mine workings were de-watered by ARCO and its predecessors through a massive underground pumping system to allow mining to continue in the pit and the other underground mines.

- In 1982, ARCO decided to cease mine operations and shut off the de-watering pumps. Groundwater in the area then started rising back to levels that existed before the mining and de-watering operations began. As the groundwater level rose, the Berkeley Pit rapidly filled with acid mine drainage from the pit walls, the network of underground mines, waste rock dumps and leach pads in the area.

“What was once a regulated mining and de-watering operation has now become a Superfund Site with the largest body of contaminated water in the United States,” said John Cruden, Deputy Assistant Attorney General for the Justice Department’s Environment and Natural Resources Division. “This settlement is a big step in healing the scars from over a century of extensive mining in Butte, and it will go a long way to protecting human health and the environment in the area.”

“This action demonstrates our strong commitment to work in partnership with states to hold responsible parties accountable for cleaning up and protecting out nation’s environment,”said Sylvia Lowrance, EPA’s Acting Assistant Administrator for Enforcement and Compliance Assurance.

The mine drainage that exists in the Berkeley Pit is highly acidic and laden with arsenic and heavy metals such as aluminum, cadmium, copper, iron, lead, zinc and sulfate. These same toxic attributes of the pit water also led to the1995 deaths of 342 snow geese, who mistook the contaminated water for a safe migratory drinking stop.

The settling defendants will continue to implement EPA’s cleanup plan for the Berkeley Pit, as ARCO has been for the past five years under a prior order from EPA. ARCO has taken the lead in implementing the remedial design and remedial action at this site, and the other settling defendants are reportedly contributing to the cost of this work under terms not disclosed to the government.

The settling parties also must reimburse roughly $3.25 million of the costs EPA so far has incurred at the site, and they will make an advance payment of $5.723 million to cover future costs that either EPA or the state incur in overseeing and monitoring the cleanup. Since the cleanup plan is likely to take decades, the settlement also contains strong financial assurances and guarantees from the defendants that they will be able to continue to finance the significant costs of cleanup in the future.

The consent decree was filed in U.S. District Court in Montana, Butte Division and is subject to a 30-day public comment period. The case name is United States v. ARCO, et al.