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Information about the Berkeley Pit.

The Berkeley Pit in 1972.

Berkeley Pit Myth Versus Fact

The Berkeley Pit in 1972.

The Berkeley Pit in 1972.

PitWatch Issue Volume 9, Number 1

The community has many common misconceptions about the Berkeley Pit. This section will address a few of those most often heard false statements and try to set the record straight.

Myth:

The Pit Will Overflow.Watch Full Movie Online Streaming Online and Download

Fact:

There are two reasons why the Pit will never overflow. First, the 1994 Record of Decision and 2002 Consent Decree established the maximum level that the water will be allowed to reach to make sure the Berkeley Pit is lowest point in the cone of depression (see center graphic). Wells to monitor water levels have been set up. Failure to keep the water below the 5410′ elevation would result in steep fines for BP/Atlantic Richfield and Montana Resources. Second, the Horseshoe Bend Water Treatment Plant is already in-place and operating. It has the capacity (7 Million Gallons per Day) to treat water from the Berkeley Pit, when it becomes necessary. This will ensure the water level remains below 5,410′.

Myth:

The Horseshoe Bend Water Treatment Plant will empty the Berkeley Pit.

Fact:

In the 1994 Record of Decision, the agencies decided that it would be unfeasible for the Potentially Responsible Parties (PRP’s) to ever completely empty the Berkeley Pit. The remedy selected for the Berkeley Pit is to treat all water inflows to maintain the level below 5,410′ above sea level.

Myth:

Congress is cutting the national Superfund program and the operation of the Horseshoe Bend Water treatment Plant will be discontinued.

Fact:

The ‘Butte Mine Flooding Superfund Site’ is the responsibility of BP/Atlantic Richfield and Montana Resources. Thus, the plant will not be affected by any changes to the EPA’s Superfund Program. The legally binding Consent Decree, which was signed by the responsible parties in 2002, established the financial commitment to operate and maintain the water treatment plant in perpetuity.

This image from the Montana Bureau of Mines & Geology illustrates the connections between historic underground mining tunnels and the Berkeley Pit. After groundwater pumping ceased in 1982, the tunnels, and eventually the Pit, began to fill with water.

Mine Resumption Affects Treatment Plant Operations

This image from the Montana Bureau of Mines & Geology illustrates the connections between historic underground mining tunnels and the Berkeley Pit. After groundwater pumping ceased in 1982, the tunnels, and eventually the Pit, began to fill with water.
This image from the Montana Bureau of Mines & Geology illustrates the connections between historic underground mining tunnels and the Berkeley Pit. After groundwater pumping ceased in 1982, the tunnels, and eventually the Pit, began to fill with water. Click on the image to view a larger version.

Since the last issue of PITWATCH, Montana Resources has decided to resume operations. With the mine going again and with the water treatment plant coming on line, there have been many questions from the community. Here are some answers to reader questions.

Q: How much total water went into the Berkeley Pit since the suspension of mining at Montana Resources?
A: About 7.5 billion gallons of water or an average of 6 mgd has gone into the Pit since MR suspended operations. An average of 3.4 mgd of this total was from the underground workings and storm water flow. An average of 2.6 mgd of this total was from the Horseshoe Bend discharge.

Q: How much water will go into the Pit once mining operations resume completely and the water treatment facility is operating?
A: The Horseshoe Bend drainage flow will be treated in the new treatment plant, and presently, this water will be entirely consumed in the mining operations. The remaining 3.4 mgd of flow from the underground workings and storm water flow will still flow into the Pit contributing to the rising level there. Eventually, when the water level approaches 5,410′ above sea level (expected about 2018), water will have to be pumped from the Berkeley Pit and treated at the Horseshoe Bend facility. Having the plant in place provides assurance that the capability is there when it becomes necessary to treat Pit water.

Q: Where will the treated water go?
A: Current plans are to treat the entire Horseshoe Bend drainage flow at the treatment plant, and then route all of the treated water to the concentrator for use in mine operations. As a result, and for as long as the treated water is used in the mining circuit, there will be no discharge off-site. In the event the mine was to suspend operations again, Horseshoe Bend drainage water would be treated to discharge standards at the plant. Then it would be transported by a pipeline, being constructed along the historic Silver Bow Creek channel (Metro Storm Drain), to its confluence with Blacktail Creek, just west of the Visitor’s Center on George Street in Butte, Montana.

The Berkeley Pit in Butte, Montana, 1984. Photo from Fritz Daily.

Mining Suspension Changes Treatment Plans

The Berkeley Pit in Butte, Montana, 1984. Photo from Fritz Daily.
The Berkeley Pit in Butte, Montana, 1984.

PitWatch Volume 5, Number 2

In July 2000, Montana Resources suspended mining operations. The suspension has had a direct impact on the Berkeley Pit water levels and efforts are underway to deal with the problem.

The immediate concern is treating the Horseshoe Bend water, which had been diverted away from the Berkeley Pit since 1996. Based on data from July 1 to September 30, 2000, about four to five million gallons per day is entering the Pit from the Horseshoe Bend flow. Montana Resources had been treating this water as part of its mine operations.

The Berkeley Pit in 1982. The water seen here is surface runoff flowing into the Leonard mine shaft to the right at the Pit bottom.

Pit Facts

The Berkeley Pit in 1982. The water seen here is surface runoff flowing into the Leonard mine shaft to the right at the Pit bottom.
The Berkeley Pit in 1982. The water seen here is surface runoff flowing into the Leonard mine shaft to the right at the Pit bottom.

PitWatch Issue Volume 4, Number 2

Pit Facts Comparison

Compare Pit elevations to those of…
the Belmont Senior Center at 5,605 feet above sea level;
East Middle School at 5,517 feet;
the Butte Airport at 5,525 feet;
the County Courthouse at 5,755 feet.

Compare the depth of Pit water to the height of…
the Anaconda smelter stack at 585 feet;
Seattle’s Space Needle at 605 feet;
Timber Butte which rises 834 feet above the Municipal Golf Course.

Compare the volume of water in the Pit to…
5 ½ Silver Lakes;
83 Basin Creek Reservoirs;
78,000 Stodden Park pools.

Pit Facts At A Glance

Current Water Level: 5,175 feet above sea level
Average Rate of Rise: About 1 foot per month
Critical Water Level: 5,410 feet above sea level
Rim of Pit at Lowest Point: 5,509 feet above sea level
Number of years before water hits Critical Level: (approximate) 21 years
Depth of Water: 702 feet (plus about 200 feet of sediment at the bottom)
Volume of Water: About 30 billion gallons

Butte, Montana, mine flooding west camp wells, shafts and area of 1960s flooding. The west camp groundwater system is monitored and maintained separately from the Berkeley Pit and connected east camp mines.

Learning About The Westcamp

Butte, Montana, mine flooding west camp wells, shafts and area of 1960s flooding. The west camp groundwater system is monitored and maintained separately from the Berkeley Pit and connected east camp mines.
Butte, Montana, mine flooding west camp wells, shafts and area of 1960s flooding. The west camp groundwater system is monitored and maintained separately from the Berkeley Pit and connected east camp mines. Click on the image to view a larger version.


PitWatch Issue Volume 3, Number 2

Previous issues of PITWATCH have been devoted almost exclusively to the Berkeley Pit and surrounding “East Camp” underground wells and mine workings. Another area of the underground water system called West Camp also deserves our attention.

The West Camp lies southwest of the Berkeley Pit/East Camp drainage and includes the Travona, Emma, and Ophir mine workings. Like in the East Camp, the groundwater in this area has been closely monitored since 1982 to make sure the water does not rise above a certain level—in this case 5,435 feet. Since November 1989, pumping operations have kept the water below this level.

In the late 1950s, the West Camp mine workings were sealed off from the rest of the shafts and drifts on the Butte Hill by a series of barriers, or bulkheads—some made of wood, some cement. Three main cement bulkheads block the connections between the Emma and Original mines at the 1,600-foot level and the Emma and Colorado mines at the 1,400- and 1,000-foot levels.

Anaconda Company crews installed the bulkheads for two main reasons: 1) they were finished mining in the West Camp and 2) they wanted to increase the efficiency of continued operations in the other mines and the Berkeley Pit. The bulkheads allowed them to eventually reduce both the volume of groundwater pumped and the area underground that required fresh air. However, even after the bulkheads were installed, they continued to pump water out of the Emma shaft until 1965.

Over the years, leakage has occurred through the bulkheads, but according to monitoring data, it appears that the West Camp water system remains mostly independent. The groundwater levels in its shafts are several hundred feet higher than those in the other mine workings, indicating that the bulkheads still separate the two areas.

After studying the West Camp in the late 1980s, the U.S. Environmental Protection Agency (EPA) ruled that the water in the Travona shaft could rise to an elevation of 5,435 feet without threatening human health or the environment. However, if the water were to rise above this level, EPA believes it could eventually flow untreated into Silver Bow Creek, and ARCO would face daily fines starting at $5,000 and increasing to $10,000 after 10 days.

To ensure that the West Camp water stays below 5,435, groundwater is pumped from the Travona shaft into a county sewer line and on to the Metro Sewer plant. ARCO pays Butte-Silver Bow about $30,000 a month to treat this water, depending on the volume received. Treatment mainly involves reducing the water’s arsenic content.

Recently, ARCO installed a larger main pump south of the Travona near Centennial Avenue. It can handle 100 more gallons per minute than the current pump (330 compared to 230), and it should go on line sometime this fall. The Travona pump will then become the back-up, used only when needed.

The old pump is due for some downtime, as it has been working at near full capacity for more than a year to keep up with rising water. For example, in September 1997, the Travona water hit 5,432 feet—just 3 feet below the critical mark. The current level, last measured on September 30, is 5,422 feet.

Butte, Montana, mine flooding west camp wells, shafts and area of 1960s flooding. The west camp groundwater system is monitored and maintained separately from the Berkeley Pit and connected east camp mines.

High Water History

Butte, Montana, mine flooding west camp wells, shafts and area of 1960s flooding. The west camp groundwater system is monitored and maintained separately from the Berkeley Pit and connected east camp mines.
Butte, Montana, mine flooding west camp wells, shafts and area of 1960s flooding. The west camp groundwater system is monitored and maintained separately from the Berkeley Pit and connected east camp mines. Click on the image to view a larger version.

PitWatch Issue Volume 3, Number 2

When the Anaconda Company stopped pumping groundwater out of the West Camp in 1965, the water level in the Travona quickly climbed to over 5,500 feet. Water started seeping into basements in the area bounded by Iron Street in the north, Front Street in the south, Montana Street in the west, and Maryland Street in the east. Surface water seeps were also observed north of Centennial Avenue between Montana Street and Missoula Gulch. In response, what became known as “Relief Well No. 21” was installed close to the spot where today’s new main pump is located. Keeping the Travona water more than 70 feet lower than it was back in 1965 should ensure that this case of ‘high water history’ won’t repeat itself.

The Berkeley Pit in 1982. The water seen here is surface runoff flowing into the Leonard mine shaft to the right at the Pit bottom.

Active Mining in Butte and the Berkeley Pit


PitWatch Issue Volume 3, Number 1 (1998)

We can explain some, but not all, aspects of the relationship between the Berkeley Pit and Montana Resources (MR), the corporation actively mining here in Butte. As you may recall, last year MR and ARCO hammered out an agreement on Berkeley Pit clean-up responsibilities, but the details were not made public. Here’s what we do know:

The Present

Horseshoe Bend. For the past two years, MR and ARCO have been diverting and treating the stream of water that once flowed directly into the Berkeley Pit from the northeast. The Horseshoe Bend diversion project has reduced by about half the amount of water entering the Pit. MR reuses this water in its concentrating operations. MR and ARCO share the project’s annual operating cost of about $2 million. Around $1.6 million of that goes toward buying and transporting lime, which is used to treat the water.
Continental Pit Dewatering. From March through October, MR pumps groundwater out of the south end of the Continental Pit to keep the area dry for future mining. Starting this summer, the company may begin pumping additional water out of the north end of the pit, with all water routed to the MR concentrator. This pumping diverts water that could otherwise flow into the Berkeley Pit from the east.

The Future

Monitoring Program Expansion. Over time, the monitoring well system will be expanded south and east to cover the entire Berkeley Pit/Continental Pit Complex, rather than just the area around the Berkeley Pit. This expansion will be necessary because groundwater pumping at the Continental Pit will eventually take place at an elevation lower than the water level of the Berkeley Pit. Pumping now occurs about 90 feet above the Berkeley Pit water level, but over the next 20 years, MR plans to expand the Continental Pit eastward and southward and mine it down to 4,986 feet—166 feet below the current Berkeley Pit water level (all USGS elevations).

When this new low spot is created, some water that would otherwise flow west toward the Berkeley may instead start flowing east toward the Continental. Water levels in the monitoring wells between the two pits (such as Well H) will be affected by this change, although exactly how they will react is unknown. Most importantly, however, all water will still be confined to the mining area with flow going toward the two pits.

Central Zone Mining. MR may also expand active mining westward into the Central Zone area between the two pits. Five bedrock monitoring wells (H, C, D1, D2, and DDH-2) lie within this zone and would be mined out. The Continental Fault, which runs along the Continental Pit’s current west border, would also be mined out, eliminating what is now a partial groundwater barrier between the two pits. MR officials said the Central Zone is rich in copper, but they also admitted that a great deal of research must be done to determine the feasibility of mining there.