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Month: August 2008

Who would be responsible for water treatment if the mine closes permanently?

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 costs from the other company.live streaming film Buster’s Mal Heart online

Is water from the Berkeley Pit expected to flow to the Continental Pit?

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 Continental Pit may be as much as 400 feet below the water level in the Berkeley. But even then, there is no expectation that Berkeley water will enter the Continental Pit.

What is the water quality of the Continental Pit compared to the Berkeley Pit?

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 Pit water.

In the future, as part of the reclamation effort, the Continental Pit water will likely require some management to sustain water levels and treatment to remove metals. However, that treatment should be less costly and less complicated compared to the Berkeley Pit.

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 they fail to pump and treat the water to keep levels below 5,410 feet, the U.S. government (EPA) can take over the project and charge these companies up to three times the project cost.

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 at the metals in the rocks and dissolves them into the water, leading to high concentrations of potentially toxic material.

Have there been any major rock slides along the Pit walls?

Yes. Wet weather may have also played a role in the 1998 Pit wall slough that sent about 3 million tons of rock and dirt into the water. Rising groundwater saturated and gradually weakened that section of the southeast wall, eventually causing it to break away.

Montana Resources, Inc. (MR) is taking steps to stabilize the piles of waste rock that form sections of the Pit walls. Two options are available: The first is to remove material from the tops of the dumps (the crests) to relieve pressure, and the second is to add material to the bottoms of the dumps (the toes) to bolster their foundations.

MR is employing both strategies to minimize future problems. Using a bulldozer, crews shaved the crest of what is called the “Bird Watch Dump” along the Pit’s south wall. And to shore up the underwater toe of another dump in the Pit’s southeast corner, crews pushed in material from the Bird Watch Dump, plus additional waste rock and dirt from the active Continental Pit.

Have the monitoring efforts revealed any surprises?

Yes. One involves changes in bedrock Well H. The water level of this well is usually about 10 feet above the level of the Berkeley Pit, just like other bedrock wells nearby. But one July, Well H’s level started falling, and by September it had dropped about 3 ½ feet. Meanwhile, the Pit kept rising. From December through February, the water levels of the Pit and Well H were just inches apart. Well H is now gaining on the Pit again.

What is the significance of the surprise reading in Well H? It appears to be an isolated incident caused by underground subsidence (shifting of dirt) adjacent to the well. Well H is southeast of the Pit in the middle of the old Pittsmont Mine workings, where the ground is known to be unstable. The water levels in all of the surrounding bedrock wells remain high, indicating that flow is still toward the Pit. It is important to look at the monitoring well system as a whole, rather than focus solely on the performance of a single well.

And Well H is not the only surprise to date. In 1989, the water level in the Kelley shaft dropped two feet in one month, but it, too, recovered. Well DDH-5 also occasionally fluctuates. The monitoring program was set up specifically to detect changes like these. When something unusual turns up, monitoring is heightened at that spot, and scientists determine what action, if any, needs to be taken. At Well H, water levels have been checked weekly since October. On February 18, a special camera was lowered 927 feet into the well to look for abnormalities, and none were found.

Future years will bring many more monitoring well changes, especially in the area between the Berkeley and Continental Pits.

How much water evaporates off the surface of the Pit?

According to Montana Resources, about twice as much water evaporates off the surface of the Pit each year than enters the Pit through rain and snow. About 12 inches of precipitation fall into the Pit each year, and about 23.65 inches evaporate, for an annual net loss from evaporation of roughly 11.65 inches. This water balance translates into an annual average of about 20,000 gallons per day of evaporating water.