April 2001

Meet Our 2001 Science Fair Winners
PitWatch Issue Volume 6, Number 1

The Committee awarded $50 savings bonds to four grade school students. Their science fair projects all explored important topics related to the Berkeley Pit. The Committee would also like to recognize Butte High sophomore Alexandra Antonioli, who won second place at the North Central Region 2 Science and Engineering Fair in Great Falls, MT and a grand prize, all-expense paid trip to the Intel International Science Fair in San Jose, CA for her project called, "An Evaluation of the Ability of Transgenically Modified Chlamydomonas reinhardtii To Survive and Sequester Metals from the Berkeley Pit."

Congratulations to everyone who competed in the Fairs, and keep up the good work! Remember, the Committee will offer awards again at the 2002 Science Fair, and students are encouraged to choose projects related to the Pit for next year's competition.

	Cara Patton 5th grade, Longfellow Elementary Horseshoe Bend Water and the Pit
	Magdalena Pesanti 6th grade, West Elementary Let's Clean Up the Pit
	Kels Phelps 7th grade, East Middle School How Sugar Affects the Growth of Fungus in Pit Water Solution and the Subsequent Impact on pH
	Leah Cornish 8th grade, East Middle School How Does Berkeley Pit Water have to be Diluted in Order to be Safe for Lettuce Seedling Growth?

Update on Plans to Treat Horseshoe Bend Water
PitWatch Issue Volume 6, Number 1

The suspension of mining operations by Montana Resources has had a direct impact on the Berkeley Pit water levels and efforts are continuing to deal with the problem. The chief task is to figure out the best way to treat the Horseshoe Bend water - an extra four million gallons of water now flowing daily into the Berkeley Pit that had been recycled into mining operations since 1996.

Meeting deadlines set forth in a contingency plan in place since 1996, Montana Resources and ARCO have started design work on a treatment facility for Horseshoe Bend water, selecting a group of engineering contractors, including MSE, HKM, and U.S. Filter, which is considered to be one of the world experts in building high density sludge (HDS) mine water treatment plants. The final design must be completed for agency review by July 1, 2001, and a facility is expected to be operational by mid-2003.

Design Options

At first, Montana Resources and ARCO considered re-tooling the concentrator for use as a treatment facility. However, after carefully evaluating the engineering, construction, and especially long-term operation and maintenance costs, the retrofit option was considered less cost-effective than building a new facility. It would also have been extremely difficult to re-engineer the plant back to a concentrator if mining operations were to resume.

Another consideration in favor of building a new plant was the capability for future expansion. Initially, by 2003, the treatment facility will need to treat up to five million gallons of water per day from the Horseshoe Bend flow. However, before too long (maybe less than 10 years), the water level in the Berkeley Pit will approach the critical level, and Montana Resources and ARCO must be prepared to treat another three million gallons per day. A new plant, to be located within the mine near the old McQueen neighborhood, would be designed for expansion and for upgrades if discharge standards were to change.

Treatment Technology

One decision that will be closely watched is which technology will be selected to treat the water. At present, a conventional, lime-precipitation facility is planned for Horseshoe Bend water, combined with the use of state-of-the-art, high-density sludge processes. The goals of the process will be to minimize the huge amount of sludge that will be generated through conventional treatment, and in turn, possibly eliminate the need for a special sludge repository which would create another problem to deal with in the future). If the volume of sludge can be reduced or somehow consolidated, it may also be possible to use the Berkeley Pit as a repository without increasing future treatment costs for Pit water.

Still, the use of conventional technology to treat Horseshoe Bend water would be a disappointment to many observers hoping for a more advanced solution - one that would allow the recovery of valuable metals as part of the treatment process, for example. In fact, EPA contemplated such a development when it established a special "technology review" (originally expected around 2007, but now as soon as 2004) before approving the treatment technology for the Berkeley Pit water. But the need to treat Horseshoe Bend water right away conflicts with the current pace of the industry to commercialize newer technologies. The best hope is that the treatment plant will be built to accommodate an innovative metals recovery process as a pre-treatment step in the future.

Building Plant Now Fulfills Cleanup Obligations and Community Objectives

Since 1994, our citizens have expressed concerns about EPA's Record of Decision to allow the Pit to fill with water. In that regard, the construction of the treatment facility for Horseshoe Bend water does bring Montana Resources and ARCO a significant step closer to fulfilling a long-standing community objective: to ensure a plant is ready and operational when the water elevation in the Berkeley Pit approaches the Critical Water Level.

Another silver lining to the immediate need to treat the Horseshoe Bend water is another source of clean water for beneficial uses. The discharge from the treatment plant - expected to be about three to four million gallons per day - will have to meet all current and future standards. Current plans are to pipe the clean water through town to a point near the newly-constructed Silver Bow Creek. From there the steady source of water will increase base stream flows during summer and improve habitat along the greenway that is now under development. Downstream water users will benefit as well.

Stay Tuned for More Developments

The Berkeley Pit Public Education Committee will continue to follow the developments regarding the Horseshoe Bend water and treatment facility plans. Future issues of PitWatch will report on decisions as they are made over the next several months.

Fall 2001

Horseshoe Bend water treatment update
PitWatch Issue Volume 6, Number 2

As reported in the last edition of PitWatch, the mine closure set in motion a string of cleanup deadlines ordered under the federal Superfund program. In July 2001, ARCO and Montana Resources were required to submit design plans to build a facility to treat Horseshoe Bend water. Here's an update of what's in those plans.

When will the facility be built? Construction is scheduled to start around May 2002 and the facility should be ready to treat water by July 2003. But if the mine re-opens before construction starts, the plant would be postponed. If the mine re-opens after plant construction begins, ARCO and Montana Resources will have to decide whether to proceed or suspend construction. If the mine re-opens after the facility is built, they may choose to keep it going, particularly if it's more practical to operate the new facility rather than going back to the process of pumping Horseshoe Bend flow up to the Yankee Doodle Pond and treating the water with lime.

Where will the facility be located? It will be built near the site of the former McQueen neighborhood, about 600 feet east of the Berkeley Pit. The facility would cover a four-acre site with a capacity to treat up to seven million gallons per day, which is about 5000 gallons per minute.

How much will it cost to build and operate? Until final engineering plans are complete and construction bids are received, costs are preliminary. But ARCO and Montana Resources have estimated facility construction between $12-22 million. The plant will cost approximately $2 million to operate each year, depending on how much water is treated.

What technology will be used to treat the water? ARCO and Montana Resources contracted with U.S Filter (who utilized local companies MSE Technology Applications and HKM Engineering as subcontractors) to design the treatment plant. The design uses a two-stage lime precipitation process with aeration and polymer addition to remove the metals from the water.

A high-tech twist is the use of a High Density Sludge (HDS) approach as part of the treatment process. This technology produces a much smaller sludge volume than conventional lime treatment (see graphic). The easiest way to describe it is that the denser sludge is produced through a recycling process, whereby the sludge generated in the water treatment process is sent through the system many times.

The process resembles a snowball effect. Each time sludge particles are sent through, they grow in size as new particles attach to the old ones. At the end, the final sludge product - like a watery mud - is much denser. Using this process, the Horseshoe Bend water can be treated clean enough to discharge into Silver Bow Creek and far less water has to be wasted as part of the sludge.

Where will the sludge be dumped? Because there will be a much smaller volume, the EPA and MDEQ are expected to allow the sludge to be dumped in the Berkeley Pit. Placing the sludge in the Pit instead of building a landfill-type repository does have advantages. It avoids tying up additional land, consolidates wastes in one location, and would ensure the sludge is always covered with water.

Final tests are almost complete to evaluate whether sludge disposal will have any adverse effects on the water in the Berkeley Pit. ARCO and Montana Resources expect the tests to show the sludge will have a minimal effect on the water chemistry and on the ability to recover the metals from the water if that option becomes economical in the future.

Will the sludge make the water level in the Pit rise faster? The sludge will add volume to the Pit - about 100,000 gallons per day. Over the long term, that would mean the water level in the monitoring wells and the Berkeley Pit would approach the critical mark of 5,410' about one year earlier, in 2017 instead of 2018 as currently predicted.

The companies and agency officials believe the benefits of sludge disposal in the Pit outweigh the costs of that extra year of water treatment. Also, since a treatment plant will already be operating, concerns about whether a plant will be built in time are eliminated.

What is the source of the Horseshoe Bend water? The Horseshoe Bend flow comes from several different springs located northeast of the Berkeley Pit, near the base of waste rock dumps and leach pads, and from the marshy areas covered by the Yankee Doodle Tailings Pond. The largest spring is the Horseshoe Bend Falls, which comprises almost half the flow. The water from these various springs and historic drainage areas is very acidic and high in metal concentrations. Flows increase following runoff and recharge from storm events for a short period of time and then return to normal.

Where will the clean, treated water go? A pipeline from the treatment plant will convey the clean water to Silver Bow Creek, with discharge planned near the railroad bridge on South Montana Street. Initially, the treated water should add about 4.5 cubic feet per second (cfs) of flow into that point on the creek, which has a base flow of about 10 cfs.

Stay Tuned for More Developments

The Berkeley Pit Public Education Committee will continue to follow the developments regarding the Horseshoe Bend water and treatment facility plans. Future issues of Pitwatch will report on decisions as they are made over the next several months.

Tailings covered to prevent blowing dust
Pitwatch Issue Volume 6, Number 2

The visibility of the recent blowing tailings events prompted numerous questions to the Committee. Although this topic is not directly related to Superfund and mine flooding issues, the Committee wanted to provide a brief update to readers.

When Montana Resources was operating, blowing dust was not a concern because water from the concentrator and the Horseshoe Bend diversion kept the tailings wet. When milling operations were suspended and the Horseshoe Bend flow was directed back to the Pit, the tailings began drying out. By October, Montana Resources had spread about 1.5 million tons of rock, approximately eighteen inches deep, to cover about 507 acres of the Tailings Pond to keep the dust down.

The blue lines in the graphic at left indicate system in place during mine operations; these water lines were discontinued when the mine ceased operation.