Under a clear EPA order, both Montana Resources and BP-ARCO are responsible for treating Berkeley Pit water. Under the Superfund law, if one company is unable to pay its share, the other company must pay all the costs of cleanup. The company paying the full cleanup costs would likely take some legal actions to recover a fair share of those […]

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Presently there is no evidence that water is moving from the Berkeley Pit to the Continental Pit or that there is any underground connection between the two pits. Right now, the mining level in the Continental Pit is below the water level in the Berkeley Pit. In the future, by the end of the mine life, the bottom of the […]

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Current sampling indicates that the water quality is significantly different in the two pits. The pH of the water in the Continental Pit is about 6.5-7.0, which is much more neutral than the water in the Berkeley Pit, which has a pH of about 2.5. Also, the levels of arsenic, copper and cadmium are many times less in the Continental […]

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Who is responsible for treating the water?

The Atlantic Richfield Co., a subsidiary of British Petroleum (ARCO or BP-ARCO) which bought out the Anaconda Co. in 1977, and Montana Resources (MR), the company now mining in the Continental Pit adjacent to the east of the Berkeley, are responsible, along with four other entities affiliated with MR: Asarco, Inc.; AR Montana Corp.; MR Inc., and Dennis Washington. If […]

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Why is the water polluted?

The water in the Berkeley Pit is a good example of acid mine drainage, which is mainly caused by the high sulfur content in the rock in the Butte Hill. The sulfur reacts with air and water to become sulfuric acid. As this acidic water (pH around 2.5) flows through the underground mine workings and rock fractures, it eats away […]

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