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Information about the science of the Berkeley Pit.

Catching up with past Science Fair winners

And announcing our winners for 2009

Since 1997, the Berkeley Pit Education Committee has given awards to area students competing in annual Montana Tech Science and Engineering Fairs who use their projects to explore important topics related to the Berkeley Pit and mine waste cleanup technologies.

At the 2009 fair, three East Middle School students received awards for Pit-related projects: Jessica Robertson for her project on cementation, Katie Metesh for her project on geothermal heating, and Robin Gammons for her project on mining copper from Butte’s groundwater. Many past winners have gone on to pursue careers in science and technology.

Kels Phelps won his first Berkeley Pit awards in 2001 and 2002. Kels went on to win a Berkeley Pit award again in 2006 for his project on the metabolites produced by a microbe growing in the unique environment of Silver Bow Creek.Kels Phelps won his first Berkeley Pit awards in 2001 and 2002. Kels went on to win a Berkeley Pit award again in 2006 for his project on the metabolites produced by a microbe growing in the unique environment of Silver Bow Creek. His research involved isolating a compound produced by the microbe and analyzing its potential for medical applications. Kels was able determine the compound’s molecular structure, and found that it displayed activity in inhibiting enzyme reactions associated with various disorders such as multiple sclerosis, Huntington’s disease, and cancer metastasis.

A double-major in philosophy and religion at Pacific Lutheran University in Tacoma, Washington, Kels is currently completing a semester studying abroad in Trinidad and Tobago. He feels that his experience doing research in the Butte area has served him well.

“The opportunities that I was able to take advantage of, specifically due to the Berkeley Pit and the Upper Clark Fork, provided excellent intellectual stimulation and helped me prepare for college.”

Emily Munday won Berkeley Pit awards in 2000 and 2003 for her projects studying mining’s impact on Silver Bow Creek using aquatic insects as bioindicators of stream health.Emily Munday won Berkeley Pit awards in 2000 and 2003 for her projects studying mining’s impact on Silver Bow Creek using aquatic insects as bioindicators of stream health. She delved deeper into Silver Bow Creek water quality by analyzing parameters such as pH; conductivity; copper concentrations in sediments, insects and water; and nutrient levels.

“I ultimately learned that copper mining has negative impacts on stream health, something that many Buttians know,” Emily stated when asked to reflect on her experience with the science fair. “However, I also learned that after remediation, Silver Bow Creek is recovering and can someday be very similar to what it was historically – before Butte’s mining days. If we continue to care for it, and locate and block or treat ongoing pollution sources like metals runoff from the hill and eutrophication from the waste water treatment plant, Silver Bow Creek will recover and be the trout fishery it once was.”

Emily currently attends Boston University, where she is busy earning a degree in marine science. As part of her studies, she traveled to Belize for a coral reef study. Last summer she interned with the Water Environment Federation at the national headquarters in Alexandria, Virginia, helping with the national Stockholm Junior Water Prize competition. This summer, she has a research grant to assess coral reef health in marine protected areas in the Caribbean. She also swims for the BU Terriers, which she describes as her “20-hour per week part-time job.”

“Studying impacted areas in my hometown and learning that there is hope for recovery made me want to use science to protect beautiful places. I am studying marine science because the ocean is an important source of biodiversity, food and oxygen production, and beauty. I want to help people learn about it so we can save it.”

Alexandra Antonioli was a recipient of a Berkeley Pit award in 2002 for her project investigating whether modification of a native Berkeley Pit microbe could be used to enhance the organism’s ability to bind heavy metals. Alexandra Antonioli was a recipient of a Berkeley Pit award in 2002 for her project investigating whether modification of a native Berkeley Pit microbe could be used to enhance the organism’s ability to bind heavy metals. Researchers at Ohio State University had modified an algal strain so that it could bind metals such as cadmium from contaminated soil. Alexandra’s goal was to insert the same gene used to modify the algae into a native Berkeley Pit yeast species. Initial results with the newly modified yeast were promising, but more research is needed to determine the full impact of the organism.

Alexandra graduated from Yale University in 2007 with a B.S. degree in Biophysics and Biochemistry. After graduating she worked full-time as a research assistant in Professor Scott Strobel’s laboratory for two years. Her research investigated an RNA structural motif called the K-turn in the Azoarcus group I intron. This type of advanced research involved structural biochemistry and crystallography.

In August 2009, Alexandra will enter the University of Colorado’s Medical Scientist Training Program where she will earn dual M.D. / Ph.D. degrees. She looks forward to being closer to Montana and is excited for a career in academia as a physician scientist.

“My interest in research started with science fair and the research with the Berkeley Pit. I was fortunate to find mentors like Professor Andrea Stierle and Professor Grant Mitman who encouraged and helped me gain valuable research skills. I think that their excitement about research helped inspire me to study science and continue with research throughout college.”

Today Alexandra considers the Berkeley Pit from a scientific perspective. “As a scientist, I view the Berkeley Pit as a place for exploration and discoveries. Andrea and Don Stierle’s lab has shown that numerous compounds can be isolated from Berkeley Pit waters that have potential antibiotic and anticancer properties. This type of research is extremely challenging because it may take years to isolate, develop, and characterize one compound. However, the rewards of finding a new compound with the drug potential to help thousands of lives are immeasurable.”

To describe her hometown to people in Boston, Emily still refers to the Berkeley Pit with a kind of stubborn pride. “I think that when it is cleaned up, we still need to remember what it looked like so we can use it as an example of how humans can change and destroy a landscape so we don’t make similar environmental mistakes in the future.”

Kels offers a similar view of the Pit, acknowledging the good and the bad. “I think that the Berkeley Pit is the result of some very serious mistakes, and I am a hearty proponent of efforts to contain the damage, and eventually try to restore it, in some way, to some semblance of naturality. I also find it very encouraging to know that, even from such a huge environmental crisis as this, there are positive discoveries that can be made. The compound isolated in my 2006 research doesn’t even begin to scratch the surface of the potential for novelty that lies in the Berkeley Pit. As long as we have to live with it, we must continue to use it in this way.”

What is pH?

The pH scale shows the acidity or alkalinity of a solution. Berkeley Pit water has a pH around 2.5.pH is a measure of the acidity or alkalinity of a solution. Pure or neutral water has a pH of 7.0. Acids are defined as those solutions that have a pH less than 7; while bases are defined as those solutions that have a pH greater than 7. The pH scale is logarithmic. Unlike linear scales, which have a constant relationship between the item being measured and the value reported, each individual pH unit is a factor of 10 different than the next higher or lower unit. For example, a change in pH from 2 to 3 represents a 10-fold decrease in acidity, and a shift from 2 to 4 represents a 100-fold (10 × 10) decrease in acidity.

The Yankee Doodle Tailings Pond, part of the active Montana Resources mine that borders the Berkeley Pit, in 2008. Photo by Justin Ringsak.

Above the Pit: The Yankee Doodle Tailings Pond

Looking west from Rampart Mountain over the Yankee Doodle Tailings Pond, located north of the Berkeley Pit, in 2007.

Looking west from Rampart Mountain over the Yankee Doodle Tailings Pond, located north of the Berkeley Pit, in 2007.

North of the Berkeley Pit stands one of the largest earthen dams in the United States. The dam, constructed from waste rock mined out of the Berkeley Pit and, in more recent years, the Continental Pit, stands over 650 feet (200 meters) tall. It holds back the Yankee Doodle tailings impoundment, also known as the Yankee Doodle Tailings Pond. As part of active mining operations, Montana Resources pumps tailings and water to the Yankee Doodle Pond. Lime rock is also added, resulting in a non-acidic pH (above 7.0) tailings slurry, thus mitigating or avoiding the phenomenon of acid mine drainage.watch T2 Trainspotting 2017 film now

The Yankee Doodle Tailings Pond, part of the active Montana Resources mine that borders the Berkeley Pit, in 2008. Photo by Justin Ringsak.

The Yankee Doodle Tailings Pond, part of the active Montana Resources mine that borders the Berkeley Pit, in 2008.

Tailings particles settle out on the south portion of the ponds. Snowmelt runoff from upper drainages also mixes with the water at the north end of the pond. These factors result in clear water with an alkaline (or non-acidic) pH and very low concentrations of dissolved metals at the north end of the pond.

When mining operations were suspended from 2000 through 2003, water was no longer pumped to the Yankee Doodle site, and the tailings deposited there began to dry out. In response to concerns from the community over dust clouds blowing in the vicinity of the tailings pond, Montana Resources spread about 1.5 million tons of rock, approximately 18 inches deep, over about 506 aces at the tailings impoundment site to keep the dust down. Since the mine reopened, the tailings deposit has remained wet, resulting in no further instances of tailings-dust clouds on Butte’s northern horizon.

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.

West Camp also part of mine flooding site

A timeline of the history of the West Camp portion of the greater Butte, Montana Superfund site, which is monitored and managed separately from the Berkeley Pit and connected East Camp mines.
A timeline of the history of the West Camp portion of the greater Butte, Montana Superfund site, which is monitored and managed separately from the Berkeley Pit and connected East Camp mines. Click on the image to view a larger version.

The anatomy of the thousands of miles of tunnels beneath the Butte Hill is daunting to consider and little understood by many. Important details, such as the distinction between the “West Camp” and “East Camp”, can cause consternation for many a curious observer.

The Berkeley Pit and surrounding underground mine workings and bedrock wells are referred to as the “East Camp”, and are separate from the “West Camp”, which is located more to the south and west. The Camps essentially refer to two water systems. In the East Camp, surface and underground water flows to the lowest point in the system, namely, the Berkeley Pit. The West Camp, whose waters never reach the Berkeley, is another story.

The West Camp lies southwest of the Berkeley Pit/East Camp drainage and includes the Travona, Emma, and Ophir mine workings. Just as in the East Camp, the groundwater in this area has been closely monitored since the suspension of pumping in 1982 to ensure that water levels do not rise high enough to significantly impact surrounding aquifers—in this case, 5,435 feet is the magic number.

Since November 1989, pumping operations have kept West Camp 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 in the West Camp and the Original mine in the East Camp at the 1,600-foot level, and between the Emma and Colorado mines at the 1,400- and 1,000-foot levels.

Anaconda Company crews originally installed the bulkheads for two main reasons: 1) there were no plans to continue mining in the West Camp, and 2) they wanted to increase the efficiency of continuing mining operations in the other underground mines of the East Camp and the Berkeley Pit.

The bulkheads allowed the company to eventually reduce the volume of both groundwater pumped out from underground shafts and the area underground that required fresh air to be pumped in. However, even after the bulkheads were installed, water was pumped out of the West Camp Emma shaft until 1965.

A clarifier, drained for maintenance, at the Horseshoe Bend Water Treatment Plant. The plant will eventually be required to treat water from the Berkeley Pit. Photo from the EPA Five Year Review Report (2011) for the site.

Treatment technology thoroughly studied

The Berkeley Pit is literally world famous in the mine waste cleanup industry, and the final technology used in the Horseshoe Bend Water Treatment Plant, a High Density Solids (HDS) process, was selected after an assessment of tests and the demonstrated effectiveness of cleanup technologies from research groups around the world.

A clarifier, drained for maintenance, at the Horseshoe Bend Water Treatment Plant. The plant will eventually be required to treat water from the Berkeley Pit. Photo from the EPA Five Year Review Report (2011) for the site.
A clarifier, drained for maintenance, at the Horseshoe Bend Water Treatment Plant. The plant will eventually be required to treat water from the Berkeley Pit.

The Horseshoe Bend facility currently treats water from Horseshoe Bend, and will eventually be used to treat water from the Berkeley. The treatment plant utilizes a two-stage lime (calcium hydroxide) precipitation process in combination with HDS technology. Lime, aeration and polymer addition remove metals from the water. The fully automated facility generates about 10 times less sludge than a conventional lime treatment plant. HDS technology produces denser sludge through a recycling process in which 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.

Horseshoe Bend Treatment Plant Sludge Reduction. Graphic by Justin Ringsak.
Horseshoe Bend Treatment Plant Sludge Reduction

The relatively low final volume of sludge – currently about 40,000 gallons per day in a 220,000-gallon slurry – is deposited in the Berkeley Pit, eliminating the need for a land-based sludge repository. Test results indicate that sludge disposal in the Pit may raise the pH of the water over a 10- to 20-year period, which could potentially decrease treatment costs for Pit water.

Due to the design of the system, treated water can easily be used in the concentration process at the adjacent Montana Resources mine, or, in the event that the mine ceases operations, discharged to Silver Bow Creek upstream from the confluence with Blacktail Creek near Montana Street. The volume of treated water should add about 4.5 cubic feet per second (cfs) of flow to the creek, which represents about a 50 percent increase to the base flow of 10 cfs.

A performance test of the Horseshoe Bend plant was completed in November 2007, as mandated by the Record of Decision. Based on the performance review, water discharged from the plant meets all discharge standards for contaminants of concern set by the EPA. Additional adjustments still need to be made to address pH. In general, plant operations are going as expected.

Limnocorrals, experimental enclosures which physically isolate a known volume of water and allow for the testing of various experimental manipulations at a relatively low cost, deployed in the Berkeley Pit. Photo by Nicholas Tucci.

Research continues on Pit Water

The unique environment of the Berkeley Pit and the surrounding Butte area has created numerous avenues for scientific exploration, both by local scientists and by researchers around the globe.

The research potential of the site is tremendous, and may represent a real renaissance for a geographic area characterized by years of mining, milling, and smelting waste. Research efforts have been undertaken locally at Montana Tech, the Montana Bureau of Mines and Geology, and MSE, and research groups from around the world have studied Pit water.

On a more local level, a cursory scan of Montana Tech Library resources turns up 23 thesis publications devoted specifically to researching aspects of the Berkeley Pit, as well as many more Pit-related research publications. And the research covers a diverse array of topics, including environmental engineering, geology, communications, metallurgy, chemistry, and physics.

A 1994 thesis by David Klemp, a graduate student in the Montana Tech Environmental Engineering program, investigated fog from Berkeley Pit water, a site familiar to most Butte residents. A 1996 thesis by Neil Massart, also from the Environmental Engineering program, offered an economic analysis of a crystallization process that was part of a broader evaluation of the potential for innovative technologies to remediate the Pit.

A large volume of additional research has focused on the study of various methods for bioremediating Pit water or the use of different technologies to treat Pit water. Other studies, like that carried out by Montana Tech Chemistry and Geochemistry graduate student Licette Hammer in 1999 and a similar study done by graduate student Margery Willett in 2001, focus on the amount and types of organic carbon present in the Pit, and the relationship between organic carbon and the larger Pit ecosystem.

In addition to the regular staff of scientists and undergraduate assistants at Montana Tech, the Stierles, at center, have also worked with local high school and middle school students over the years on science fair projects focused on Berkeley Pit microbes. The realization that a compound that could help cure cancer could be lurking in the Berkeley Pit is thrilling. They like to think that their microbes could be some of the richest "ore" ever mined from the Richest hill on Earth. Photo courtesy of Lisa Kunkel, The Montana Standard.
In addition to the regular staff of scientists and undergraduate assistants at Montana Tech, the Stierles, at center, have also worked with local high school and middle school students over the years on science fair projects focused on Berkeley Pit microbes. The realization that a compound that could help cure cancer could be lurking in the Berkeley Pit is thrilling. They like to think that their microbes could be some of the richest “ore” ever mined from the Richest hill on Earth. Photo courtesy of Lisa Kunkel, The Montana Standard.

Local scientists Drs Andrea and Don Stierle, both faculty members in the Department of Chemistry and Geochemistry at Montana Tech, recently garnered national publicity for their research, ongoing since 1996, on microbes living in the Berkeley Pit Lake. The unique nature of the Pit environment creates habitat for unusual microbes, sometimes called “extremophiles”, which could in turn produce novel chemistry with potential medical uses. The organisms themselves may also be effective bioremediators of the wastewater in which they grow.

The Stierles, aided by undergraduate research assistants at Montana Tech and local high school students and collaborating with scientists at Montana State University and the University of Montana, are “mining” these Pit microbes. They have already isolated several exciting new compounds, including a migraine preventative and several compounds with promising anticancer potential. They have also found an intriguing fungus that appears to pull metals from the Pit water itself.

The research process is complex. Microbes must first be isolated from water and sediment samples and established in pure cultures. A variety of carbon and nitrogen sources are used to determine which growth conditions yield the most active natural products. Extracted microbial cultures are tested to determine if they have potential as antibacterial, antifungal, anticancer, or immune system modulating agents.

The Stierles have been awarded almost $3 million in federal funding from the National Institutes of Health and the US Geological Survey to support their ongoing efforts at drug discovery from an acid mine waste lake.

Other scientists have experimented with the potential of algae to clean or bioremediate the Berkeley Pit. For most of the past decade, Dr. Grant Mitman, a Montana Tech biology professor, has been studying the ability of algae to remove heavy metal contaminants from Pit water. Through various metabolic, physiological, and biochemical processes, algae have the potential to reduce soluble metal ions in acid mine waters.

Limnocorrals, experimental enclosures which physically isolate a known volume of water and allow for the testing of various experimental manipulations at a relatively low cost, deployed in the Berkeley Pit. Photo by Nicholas Tucci.
Limnocorrals, experimental enclosures which physically isolate a known volume of water and allow for the testing of various experimental manipulations at a relatively low cost, deployed in the Berkeley Pit.

Dr. Mitman, along with graduate student Nicholas Tucci, applied this potential bioremediation solution in the Berkeley Pit in 2006. Algae occur naturally in the Pit, but lack nitrate, a common nutrient found in most fertilizers that is essential for algal growth. If nitrate is added to Pit water, the naturally occurring algae can potentially reach a concentration of millions of cells per milliliter, a virtual green soup of suspended organisms that have an ability to permanently remove dissolved metals from the pit. These organisms have been used to remediate other pit lakes around the world, and may one day lead to the natural restoration of the Berkeley Pit.

In the spring of 2004, Mitman and Tucci deployed nine acid- and metal-resistant cylindrical limnocorrals along the eastern edge of the Berkley Pit Lake. Limnocorrals are experimental enclosures which physically isolate a known volume of water, and allow for the testing of various experimental manipulations at a relatively low cost.

In this case, 500 gallons of pit water were used to fill the limnocorrals, and varying concentrations of nitrate were added as the experimental variable.

To determine if algal growth had an effect on Berkeley Pit water, water quality and algal populations in nutrified limnocorrals were continually monitored and compared with those in non-nutrified limnocorrals.

After the first year of data collection, concentrations of algae in the nutrified limnocorrals had increased from undetectable levels to two million cells per milliliter, and, as a result of this algal growth, both iron and arsenic concentrations in Pit water were significantly reduced. No significant changes in water quality or algal growth were detected in the non-nutrified limnocorrals.
Researchers are planning longer-term experiments testing the ability of algae to clean Berkeley Pit water. Algae, like other biological organisms, need time to achieve a substantial and healthy population. Long term experiments will be necessary to fully determine the potential for bioremediation in the Berkeley Pit.

While substantial research has been done on the Pit, there is clearly still a lot to learn. That is an exciting prospect for the Butte community, and in the future what we can learn from the Pit could represent the greatest treasure of the Richest Hill on Earth.

Montana Resources copper precipitation plant adjacent to the Berkeley Pit. A 2013 slough of material from the Pit wall into the water knocked out the 'precip' pump, and precip operations have since ceased. In precipitation, the copper-rich water is pumped over scrap iron, and, in a replacement reaction, the copper solidifies as sludge, while iron takes its place in the water. The water was returned to the Pit by gravity flow, thus not increasing or decreasing the total volume of Pit water. Photo by Justin Ringsak.

Montana Resources mines the water

The Past

Butte’s Memory Book tells the story of Jim Ledford, a miner who lived in a log cabin below the famed Anaconda Mine. Alongside his cabin was an old dump containing scrap iron and tin cans. Mine water ran downhill through the dump, and Ledford noticed a heavy sludge formation. Out of curiosity, he had the sludge assayed and learned that it was 98-percent-pure copper.

Legend has it that Ledford told no one about his discovery. Instead, he quietly secured a one-year contract to handle the Anaconda mine water. He set up tanks, filled them with scrap metal, and ran the water through them. The undated account said his efforts earned him $90,000 that first year. His contract was not renewed.

A professional paper from a 1913 Butte mining conference tells a slightly different story. It states that in 1890 a William Ledford obtained a contract to handle water from the St. Lawrence Mine. The story ends the same, however, once the Anaconda Company realized the value of mine water, it built its own copper tanks, and copper precipitation using scrap iron became standard operating procedure. Thanks to Al Hooper for loaning his copy of the 1913 mining conference proceedings.

A third version of the story was relayed in the April 18, 1906 edition of The Montana Standard as part of a series of articles on “Queer Spots in Butte.” According to this version, in 1888 an old Welshman named Morgan who lived on the Butte Hill noticed copper dust left behind from tin cans thrown into a gully filled with runoff water from the mines. Morgan had the dust assayed and learned that it was almost pure copper. He experimented with the concept and developed a rudimentary precipitation plant, but died a few months after he had his plant operating successfully.

The story goes on to claim that a Butte Dutchman named Fred Miller dug holes in the side hill in the gulch below the St. Lawrence mine. He filled these holes with tin cans and scrap iron, allowing mine runoff water to flow over them.

For the next two or three years, he would collect the resulting copper dust every few weeks. Miller fraudulently claimed a monopoly on this system, and on several occasions tried to bluff out others on the hill who were experimenting with precipitation. The story notes that at this point William Ledford secured a lease to the St. Lawrence water, and Miller’s heyday came to an end.

The Present

Montana Resources copper precipitation plant adjacent to the Berkeley Pit. A 2013 slough of material from the Pit wall into the water knocked out the 'precip' pump, and precip operations have since ceased. In precipitation, the copper-rich water is pumped over scrap iron, and, in a replacement reaction, the copper solidifies as sludge, while iron takes its place in the water. The water was returned to the Pit by gravity flow, thus not increasing or decreasing the total volume of Pit water. Photo by Justin Ringsak.
Montana Resources copper precipitation plant adjacent to the Berkeley Pit. A 2013 slough of material from the Pit wall into the water knocked out the ‘precip’ pump, and precip operations have since ceased. In precipitation, the copper-rich water is pumped over scrap iron, and, in a replacement reaction, the copper solidifies as sludge, while iron takes its place in the water. The water was returned to the Pit by gravity flow, thus not increasing or decreasing the total volume of Pit water.

This method of copper recovery was not new: it dates back to medieval Europe. The Anaconda Company used it for years to recover copper from the water pumped from the underground mines, and the method is still used today. Montana Resources has mined copper from the rich mineral waters of the Berkeley Pit since 1998, pausing when mining operations were suspended from 2000 through 2003, then resuming in 2004 until a Pit slough in 2013 knocked out the necessary pump. The mine pumped out roughly 13 million gallons of Pit water per day, or about 10,000 gallons per minute.

In copper precipitation, the Pit water is piped to the company’s precipitation plant, built in the 1960’s next to a similar one from decades earlier. The water flows into concrete cells filled with scrap iron, and then chemistry takes over. Simply put, the iron in the cells and the copper in the water trade places. The water is returned to the Pit with a higher iron content, and the copper precipitates, or solidifies out of solution, clinging to the remaining iron.

The waterfall formerly visible on the southeast rim of the Pit, seen here in 2004, created by returning Pit water that has gone through Montana Resources copper precipitation plant. Photo by Josh Peck.
The waterfall formerly visible on the southeast rim of the Pit, seen here in 2004, created by returning Pit water that has gone through Montana Resources copper precipitation plant.

The chemical reaction does not take long. Water stays in contact with the iron for only about an hour, and then it flows back into the Pit through a separate ditch along the old Horseshoe Bend channel, which could be seen from the viewing stand as the waterfall on the northeast rim of the Pit. Mine officials say that this constant circulation process should not affect the water level of the Pit, nor should the change in water chemistry have an effect on eventual water treatment operations.

Once per week, crews drain each cell to recover the precipitated copper. A front-loader scoops up the copper and scrap iron mixture and transports it to a vibrating screen. Water sprayed from high-pressure hoses knocks the copper through the screen into a tank below. Remaining iron goes back to the cells for reuse. The cement copper concentrate is then shipped to the concentrator and processed through a filter press to reduce the water content for rail shipment. By pumping water from the Berkeley, the company recovered about 400,000 pounds of copper per month.

The company also routed copper-rich Horseshoe Bend water through the precipitation plant from 1998 until the mine shutdown of 2000. The sale of this precipitated copper helped to offset water treatment costs. Once through the precipitation plant, Horseshoe Bend water was mixed with lime (calcium hydroxide) and pumped north to the Yankee Doodle Tailings Pond.

Since the treatment plant went online in 2003, this Horseshoe Bend water has been kept out of the precip plant circuit.

The equation below shows the main chemical reaction that takes place during the copper precipitation process:

Fe + CuSO4 becomes FeSO4 + Cu

Two aquifers feed into the Pit

Water from two different underground areas, or aquifers, affects the Berkeley Pit. The illustration above illustrates the difference between these aquifers, the alluvium and bedrock.
Water from two different underground areas, or aquifers, affects the Berkeley Pit. The illustration above illustrates the difference between these aquifers, the alluvium and bedrock.

Aquifers are places where water is found in permeable rocks and soils underground. The area around the Berkeley Pit contains two main underground aquifers – the alluvial aquifer and the bedrock aquifer. The alluvial aquifer is closer to the surface. Water flows freely through the layer of ground called the alluvium, a porous mixture of sands, gravels, and clays. Near the east wall of the Pit, the alluvium is saturated with water from this aquifer.

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.

The bedrock aquifer runs deep below the ground. It is a “confined aquifer” trapped within fractured bedrock which water cannot easily pass through. In areas adjacent to historic mining activities, this aquifer was dewatered by large pumps located underground to allow for underground mining. Up to 5,000 gallons of water per minute were pumped from the underground mines to allow for mining, including the Berkeley Pit.

The large stainless steel pumps located underground in the Kelley Mine were turned off in 1982, and since that time the dewatered area has been filling back up.

These two aquifers are independent systems, separated by a thick layer of clay-rich weathered bedrock that hinders water from the alluvial aquifer from seeping down into the bedrock aquifer. Instead, water from both aquifers is flowing toward the Pit because it is the lowest spot in the area.

The workings of a typical monitoring well in the Berkeley Pit system are shown in the illustration above.
The workings of a typical monitoring well in the Berkeley Pit system are shown in the illustration above. Click on the image to view a larger version.

Monitoring wells installed throughout the area are used to closely track the water levels and the water quality of both aquifers. Since monitoring began, the alluvial aquifer has remained fairly constant, fluctuating only a few feet here and there depending on seasonal precipitation.

In contrast, the water levels of the bedrock aquifer in areas of historic dewatering have been steadily rising to pre-mining levels. Water levels in the bedrock system have risen hundreds of feet and show minimal seasonal trends. The monitoring wells also allow scientists to measure the pressure differential between the two aquifers, expressed in pounds per square inch, or psi.

Limnocorrals, experimental enclosures which physically isolate a known volume of water and allow for the testing of various experimental manipulations at a relatively low cost, deployed in the Berkeley Pit. Photo by Nicholas Tucci.

Can Algae Clean the Berkeley Pit?

Limnocorrals, experimental enclosures which physically isolate a known volume of water and allow for the testing of various experimental manipulations at a relatively low cost, deployed in the Berkeley Pit. Photo by Nicholas Tucci.
Limnocorrals, experimental enclosures which physically isolate a known volume of water and allow for the testing of various experimental manipulations at a relatively low cost, deployed in the Berkeley Pit.

What started off as small experiments in the laboratory studying Berkeley Pit water in small flasks, has transformed into a much larger, bench-scale field experiment using the Berkeley Pit lake as the laboratory and limnocorrals as giant test tubes suspended in the contaminated water.

For most of the past decade, Dr. Grant Mitman, a Montana Tech biology professor, has been studying the ability of algae to remove heavy metal contaminants from Berkeley Pit water. Through various metabolic, physiological, and biochemical processes, algae have the potential to reduce soluble metal ions in acid mine waters. Dr. Mitman, along with his graduate student, Nicholas Tucci, have applied this potential bioremediation solution in the Berkeley Pit.

Algae occur naturally in the Berkeley Pit, but they lack one essential nutrient for growth-nitrate-a common nutrient found in most fertilizers. If nitrate is added to pit water, the naturally occurring algae can potentially reach a concentration of millions of cells per milliliter, a virtual green soup of suspended organisms that have an ability to permanently remove dissolved metals from the pit. These organisms have been used to remediate other pit lakes around the world, and may one day lead to the natural restoration of the Berkeley Pit.

In the spring of 2004, Mitman and Tucci deployed nine acid- and metal-resistant cylindrical limnocorrals along the eastern edge of the Berkley Pit Lake. Limnocorrals are experimental enclosures which physically isolate a known volume of water, and allow for the testing of various experimental manipulations at a relatively low cost. In this case, 500 gallons of pit water were used to fill the limnocorrals, and varying concentrations of nitrate were added as the experimental variable. Each limnocorral, open at the top and closed at the bottom, measured three feet in width and 10 feet in depth.

Throughout the course of a year, water-quality criteria and algal populations in nutrified limnocorrals were continually monitored and compared with those in non-nutrified limnocorrals to determine if algal growth had an effect on Berkeley Pit water. After the first year of data collection, concentration of algae in the nutrified limnocorrals had increased from undetectable levels to two million cells per milliliter. Additionally, as a result of algal growth, both iron and arsenic concentrations in the pit water were significantly reduced in the nutrified limnocorrals. No significant changes in water-quality or algal growth were detected in the non-nutrified limnocorrals.

The researchers are planning longer term experiments testing the ability of algae to clean Berkeley Pit Water. Algae, like any other biological organisms, need time to achieve a substantial and healthy population. Long term experiments are necessary to fully determine the bioremediation potential in the Berkeley Pit.

In addition to the regular staff of scientists and undergraduate assistants at Montana Tech, the Stierles, at center, have also worked with local high school and middle school students over the years on science fair projects focused on Berkeley Pit microbes. The realization that a compound that could help cure cancer could be lurking in the Berkeley Pit is thrilling. They like to think that their microbes could be some of the richest "ore" ever mined from the Richest hill on Earth. Photo courtesy of Lisa Kunkel, The Montana Standard.

Bioprospecting in the Berkeley Pit


The search for valuable natural products from a most unnatural world

by Andrea and Don Stierle

In addition to the regular staff of scientists and undergraduate assistants at Montana Tech, the Stierles, at center, have also worked with local high school and middle school students over the years on science fair projects focused on Berkeley Pit microbes. The realization that a compound that could help cure cancer could be lurking in the Berkeley Pit is thrilling. They like to think that their microbes could be some of the richest "ore" ever mined from the Richest hill on Earth. Photo courtesy of Lisa Kunkel, The Montana Standard.
In addition to the regular staff of scientists and undergraduate assistants at Montana Tech, the Stierles, at center, have also worked with local high school and middle school students over the years on science fair projects focused on Berkeley Pit microbes. The realization that a compound that could help cure cancer could be lurking in the Berkeley Pit is thrilling. They like to think that their microbes could be some of the richest “ore” ever mined from the Richest hill on Earth. Photo courtesy of Lisa Kunkel, The Montana Standard.

Most people think of the Berkeley Pit as a large toxic waste lake, an unfortunate relic of Butte’s proud mining heritage. Don and Andrea Stierle, however, see the Pit as something more. Like most of their Natural Products Chemistry colleagues, the Stierles could be searching the rainforests of Brazil or combing Caribbean reefs for plants and microorganisms that could yield promising new drug leads. Instead they are exploring the uncharted expanses of the Berkeley Pit, which they see as a unique ecosystem with treasures beyond the vast amounts of copper dredged from this site for over 25 years.

Anyone living in Butte is probably familiar with the history of the Pit and its current status as a mine waste lake. The Superfund strategy will keep the 36 billion gallons of acidic, metal-rich water from ever escaping the Pit. Until 1995, however, little attention was paid to the biological aspects of this bleak ecosystem because it was considered too toxic to support life.

Andrea and Don Stierle set out to change that belief as they launched a new type of exploration in Berkeley Pit Lake – mining for microbes. And not just any microbes – they were looking for microbes that could produce new compounds with real drug potential.
The Stierles are not new to drug discovery. For the past twenty years they have looked for anti-AIDS compounds in Bermudian sponge bacteria, anticancer agents in the bark of redwood trees, and in 1993 found a fungal source for taxol, an important anticancer compound previously isolated exclusively from the bark of the elusive yew tree. Andrea even had the fungus named after her. But they had never before explored acid mine waste as a source of the next anticancer agent.

Since 1996 the Stierles, and their team of undergraduate researchers, have isolated and studied a collection of over fifty culturable bacteria and fungi from one of the more extreme environments in the lower 48 states.

The Stierles believed that this unusual environment would harbor unusual microbes, which could in turn produce novel chemistry that can be exploited in many ways. The organisms themselves may also be effective bioremediators of the wastewater in which they grow. Their metabolic by-products could have a tremendous impact on the overall ecology of the Pit Lake system by raising the pH of the Pit water, by providing nutrients for other heterotrophs, and by adsorbing metal contaminants. Thus, the research potential of this site is tremendous, and may represent a real renaissance for a geographic area characterized by years of mining, milling, and smelting waste.

The Stierle lab uses a unique tool chest for their “mining venture”. Armed with chromatography columns, signal transduction enzyme inhibition assays, a series of antimicrobial testing schemes, and a nuclear magnetic resonance spectrometer assay, they are literally mining this unnatural system for microbes that produce bioactive natural products.

Microorganisms have been an important source of anticancer agents and antibiotics agents of all types since the discovery of penicillin in the 1930’s and 40’s. Over the years pathogenic microbes develop resistance to widely used drugs and newer more effective antibiotics must be found.

The challenge of Natural Products Chemists like the Stierles is to find new populations of microbes and to effectively isolate compounds with desired biological activity from these organisms. The Stierles have already isolated several exciting new secondary metabolites from the microbial inhabitants of this unusual ecological niche. These compounds include a migraine preventative and several compounds with promising anticancer potential. They have also found an intriguing fungus that appears to pull metals from the Pit water itself.

How would you actually find new bioactive compounds from a Berkeley Pit microbe? It is a complex process. First, the Stierles isolated microbes from water and sediment samples and established them in pure cultures. Each microbe was grown in a series of small liquid culture broths to provide adequate biological material for testing and analysis. This is not an ecological study so the Stierles are not limited to nutrient broths that mimic conditions in the Pit Lake. Instead they use a variety of carbon and nitrogen sources and determine which growth conditions yield the most active natural products. To determine the activity of the compounds produced by their microbes the Stierles must first thoroughly extract each microbial culture using different organic solvents. These extracts are then tested using a series of bioassays or biological tests that can determine if they have potential as antibacterial, antifungal, anticancer, or immune system modulating agents. These tests are used to guide the isolation of pure active compounds from the complex microbial extracts.

Each extract is first tested against a suite of human pathogenic microorganisms, including Staphylococcus aureus, and Streptococcus pneumoniae. In collaboration with Montana State University researcher Allen Harmsen the Stierles are also looking for compounds that show activity against Pneumocystis carinii, causative agent of Pneumocystis carinii Pneumonia, an indicator disease of AIDS patients, and Aspergillus, causative agent of aspergillosis, both of great concern in immunocompromised individuals.

To find compounds with anticancer activity the Stierles use a complex series of signal transduction enzyme assays that identify specific enzyme inhibitors. Inhibition of key enzymes can be an indication that a compound could block the initiation or spreading of cancer cells. In collaboration with University of Montana researcher Keith Parker the Stierles are also looking for compounds with antimigraine activity. The first compound they isolated from their Pit microbe collection showed promise as a migraine preventative.

Looking for active natural products in this unnatural world has been exciting and challenging for the Stierle Research Lab. Although their first four years of work were completely self-funded they have been able to attract support from the US Geological Survey and from the National Institutes of Health. Through their funding they have been able to create new jobs in Butte, hiring two research scientists and a host of talented undergraduates to help them with their work. They have also worked with very talented and hard-working Butte High School students Alexandra Antonioli and Kels Phelps, and East Middle School student Randi Phelps whose ongoing Science Fair projects focused on Berkeley Pit microbes. And Andrea has found that after 26 years at Montana Tech, it has been nice to actually earn a real salary for all of the work she does in the lab. But it isn’t the funding that keeps the Stierles looking for new compounds. It is the thrill of discovery, the realization that a compound that could help cure cancer could be lurking in the Berkeley Pit. They like to think that their microbes could be some of the richest “ore” ever mined from the Richest Hill on Earth.