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.
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 has the dubious distinction of being at the upper end of the largest complex of federal Superfund sites in the U.S. This Superfund complex extends from Butte and Anaconda 120 miles down the Clark Fork River to Missoula.
The word “Superfund” is tossed around a lot by local and state officials working in the Clark Fork Basin, but, to the average citizen of western Montana, the term might not mean very much. Nevertheless, Superfund is changing the landscape of western Montana, from the Berkeley Pit to the Anaconda Smelter all the way downstream to the former Milltown Dam.
In simple terms, Superfund refers to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980. This federal law, passed in the wake of environmental disasters like Love Canal, was designed to clean up abandoned hazardous waste sites that may endanger public health or the environment.
The law authorizes the Environmental Protection Agency (EPA) to identify parties responsible for contamination of sites and compel the parties to clean up the sites. Where responsible parties cannot be found, EPA is authorized to clean up sites itself using federal funding.
The Superfund cleanup process is very complex. It involves the steps taken to assess sites, place them on the National Priorities List, and establish and implement appropriate cleanup plans. This is the long-term cleanup process. EPA also has the authority to remove hazardous wastes where immediate action needs to be taken; to enforce against potentially responsible parties; to ensure community involvement; to involve states; and ensure long-term protection.
According to the EPA, as of August 5, 2013 there are 1,320 sites listed on the National Priority List, an additional 365 have been delisted, and 54 new sites have been proposed. There are currently 17 National Priority List sites in Montana, and two Superfund sites that are not part of the National Priority List.
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 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.
The facility was designed to treat up to seven million gallons per day, or about 5,000 gallons of water per minute. The facility cost approximately $18 million to build, and, depending on how much water is treated, operating expenses run about $2 million per year.
Once the Berkeley Pit water comes online, which is projected to happen in 2023, annual operation and maintenance costs could be as high as $4.5 million. Under the terms of the 2002 Consent Decree negotiated with the government, BP-ARCO and Montana Resources have agreed to provide financial assurances to pay operation and maintenance expenses in perpetuity. The two companies also paid all construction costs for the facility.
The actual construction of the treatment plant was a massive undertaking. It is estimated that workers put in 125,000 hours of total labor, and the facility also required more than 4,500 cubic yards of concrete.
The general construction contractor and subcontractors were all from Montana, with several from Butte, and, during the course of construction, they reported no safety incidents of any kind.
As per the schedule listed in the 1994 EPA Record of Decision and included in the 2002 Consent Decree, based upon current water level projections, a review of the Horseshoe Bend Water Treatment Plant design and operation would begin in 2019. Any necessary upgrades would have to be completed by 2021, two years before Pit water itself is currently projected to be pumped and treated in 2023.
In November, 2007, a performance review of the Horseshoe Bend plant was completed by Montana Resources, ARCO, and North American Water Systems, with cooperation from the Montana Bureau of Mines & Geology, the Department of Environmental Quality, and the EPA.
The performance test was undertaken to ensure that the treatment system is capable of meeting the water quality standards set in the Consent Decree for the site. For this test, only water from the Horseshoe Bend drainage was treated, as water from the Pit is not yet required to be pumped and treated at the plant.
The test began on November 18, 2007, and continued for 72 hours. All of the water quality standards for contaminants of concern were met. Additional adjustments still need to be made to address pH. For this test, the pH was kept at a high (basic or alkaline) level in order to effectively remove contaminants of concern and meet water quality standards.
The optimization of the plant in the future may result in a lower pH. Additionally, methods of adjusting the pH prior to discharge to Silver Bow Creek have been evaluated conceptually. Any method of adjusting the pH will be formally evaluated, if necessary, before any water from the plant is discharged to Silver Bow Creek.
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.
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.
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.
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.
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.
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.
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.
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 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.
From grade school through college, many classes have visited the Pit in order to learn about science, mining, and the history of the region.
In the past year, students from not only the Butte area, but also from around Montana made the trip to the Pit. Middle school students from Bonner school and college students from Montana State University-Billings and the University of Montana Environmental Studies programs have visited the Pit and the Butte area annually for the past few years.
Teachers as well as students are learning from the Pit and taking that knowledge back to their classrooms. For example, in 2007 Montana Resources provided a tour of the Pit and surrounding area for a group of 15 western Montana teachers. Seeing the Pit up-close and in-depth provides teachers with real-world examples of science concepts and issues that can then be used to engage students in the classroom.
These inquisitive spectators have learned about the details of the Pit from a variety of community volunteers and experts. Butte resident Joe Griffin, an environmental science specialist with the Department of Environmental Quality, offers students a comprehensive view of the science surrounding the Pit.
Tad Dale regularly takes time away from his busy schedule at Montana Resources to share his wealth of knowledge about the Pit and mining. Scientists from the Montana Tech faculty often come out to discuss the Pit in light of their specialties, whether it is Andrea and Don Stierle talking about biology and their research on the unusual microbes living in the Pit environment or Colleen Elliott presenting the geological context of the Pit.
And, of course, thousands of tourists learn about the Pit every year through the Butte trolley system, guided by knowledgeable locals like Butte High School history teacher Chris Fisk. Thanks to the contributions of knowledgeable Butte citizens like these, the Berkeley Pit viewing stand serves as an exciting classroom for exploring environmental sciences.
There are several reasons why we don’t need to be overly concerned about the Pit in the event of an earthquake, including the fact that there has been no significant seismic activity in nearby faults during the 28 years that the Earthquake Studies Office has been monitoring the area.
In the mining region, the recorded seismic activity is mainly caused by a few mining blasts per week, however, two landslides in the pit have been recorded in the last 28 years and a few very small, non-mining related earthquakes are recorded within Butte Silver-Bow county annually. Most seismic activity in Montana occurs outside of Silver-Bow County, and in the worst-case scenario, a large earthquake could cause landslides or sloughing in the Pit, but would not cause the Pit to overflow. Such an earthquake would cause considerably more damage to buildings and structures in the Uptown area than to the landscape or Pit.
According to the Earthquake Studies Office, there have been approximately 20 very small earthquakes within 25 km of Butte in the past year, ranging in magnitude from -.2 to 1.9. Nineteen of these were less than magnitude 1.0, and only 4 were located within Silver-Bow County. Three of these events were non-mining related events in Butte and were not large enough to be felt.
There have been no reports, past or present, of any earthquake damage to the Pit and the last earthquake greater than magnitude 1.0 in the area was a 2.8 on October 9, 2005, located 3.3 kilometers west-southwest of Butte along Silver Bow Creek.
After several highly publicized incidences of bird deaths at the Berkeley Pit, a popular myth arose: migratory waterfowl are instantly killed if they land on water in the Berkeley Pit. In fact, hundreds of waterfowl land on the surface of the Berkeley Pit every month during migration seasons, and they typically fly off unharmed within a few hours, either on their own or through Montana Resource’s hazing activities, also known as the waterfowl mitigation program.
The 2002 Consent Decree recognizes that “birds exposed to Berkeley Pit water for less than 4-6 hours should not be at substantial risk.” If a bird is observed suffering from the effects of water toxicity, it is netted and brought on board the houseboat used to patrol the Pit lake. The bird is placed in a 5-gallon bucket of fresh water and brought to shore. It is then transported to a veterinarian or released into fresh water at the north end of the Yankee Doodle Tailings Pond; tailings particles settle out on the south portion of the pond, leaving clear, alkaline (or non-acidic) water in the north end which mixes with snowmelt runoff from upper drainages, resulting in very low concentrations of dissolved metals.
In November 1995, a flock of snow geese landed on the Pit lake. After several days of stormy weather and fog, 342 birds were found dead. In response to this incident, the two responsible parties for the Pit under federal Superfund law, Montana Resources and British Petroleum-Atlantic Richfield, also known as BP-ARCO, implemented a waterfowl mitigation plan, which was approved by the EPA and other agencies in May 1998. This program is aimed at locating waterfowl in the area and then inciting the birds to fly away. An observation station was set up overlooking the Pit area. This station is an enclosed building equipped with spotting scopes and spotlights for night viewing to locate, count and identify species of waterfowl on the Pit lake.
Montana Resources’ personnel make hourly observations for birds during the spring and fall migrations, while the pit is not frozen, and cut back to 5-6 observations per day during non-migratory seasons. A variety of devices are used to chase birds off the water and out of the Pit. From the observation station near the southeast rim of the Berkeley Pit, Montana Resources’ personnel use rifles and shotguns to scare birds into the air.
In addition, three Phoenix Wailers – high-tech devices that emit predator and electronic sounds – are located near the surface of the Pit lake to discourage birds from landing. A 22-foot houseboat, docked near the pump barge, is used for periodic excursions on the water to haze waterfowl that ignore other warnings. Not all types of birds react to hazing. Typically, most ducks, geese and swans will react immediately to the noises. Diver birds such as grebes and loons tend to go underwater as a natural defense mechanism when they are alarmed.
Normally, if birds are not hazed or disturbed, they leave the Pit area at nightfall. If a dead bird is found on the water or near the Pit, then the US Fish and Wildlife Service is contacted. They decide if an autopsy is necessary.
From 1995 through 2004, 75 birds were found dead. The advances made to deter migrating waterfowl from landing on the water or staying on the Pit appear to be working. Thousands of birds land and are hazed off of the Pit each year.
Though many local authorities decided that the 1995 incident was isolated and not likely to happen again with the safeguards that are in place, in October 2007, 37 birds, including ducks, geese, and one swan, were found dead at the Pit after a weekend of fog. It is unclear why mitigation activities failed to haze these birds away from the site, although the weather was almost certainly a factor. As the mitigation program continues, all involved continue to work to keep such incidents to a minimum.
The chart below, from the 2011 EPA Five Year Review Report on the site, shows Pit-related bird deaths from 2006-2009.