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A piece of gypsum ‘scale’ removed from the Horseshoe Bend Water Treatment Plant.

Following up on the EPA’s 2010 five-year review

In 2010 EPA interviewed local citizens and reviewed the status of Butte area Superfund sites as part of a required five-year review (the full review report is available here). Five-year reviews determine whether remedies or other response actions are protective of human health and the environment in compliance with a site’s decision documents. Methods, findings, and conclusions are documented in five-year review reports that identify issues found and make recommendations to address them.

The 2010 review identified six main issues related to the Butte Mine Flooding Operable Unit (BMFOU), which includes the Berkeley Pit. All involved the performance of the Horseshoe Bend Water Treatment Plant, which was completed in 2003.

The plant currently treats contaminated surface water flowing in from the north. This water is diverted away from the Pit, slowing the rate of rise of the water. Eventually, when the water level at any compliance point reaches the Critical Level of 5,410 feet, the plant will pump-and-treat Pit water to keep levels below that critical point. A performance test was conducted at the plant in 2007, and that data was considered in the 2010 review.

All treated water is currently recycled to Montana Resources active mining operations and is not discharged to Silver Bow Creek or any other surface outlet, Consequently, EPA identified all issues in the review as potential future issues that do not effect the current protectiveness of the remedy. Montana Resources does not allow any water to discharge from the Berkeley Pit and active mine area.

Issue 1: pH

Water treated at the plant did not meet the final pH standard. pH measures the acidity of a liquid. The pH is purposely raised to over 10 in order for it to be used as operating water in Montana Resource’s mill. Discharge standards only apply when water is discharged to Silver Bow Creek.

Issue 2: Gypsum scaling

Gypsum scale build up on the lip of the treatment plant clarifier overflow.
This photo from EPA’s 2010 five-year review report shows gypsum scale build up on the lip of the treatment plant clarifier overflow.

During the water treatment process, gypsum sometimes builds up, or ‘scales’, on the inside of tanks and pipes. This leads to a need for additional maintenance, as parts of the plant must be shut down for a short period each year so that crews can remove the build up. Measures to help manage and reduce scaling are being evaluated, and gypsum concentrations are monitored weekly.

Issue 3: Cadmium

Testing showed that treated water at times did not meet the standard for cadmium, a toxic metal. After adjustments were made to increase the pH, the standard for cadmium was met.

Issue 4: Test did not include treatment of Pit water

The 2007 performance test measured treated surface water from Horseshoe Bend. While this water is similarly contaminated, Pit water has higher concentrations of toxic metals and sulfate.

Issue 5: Scale Inhibitors used to control gypsum may effect metals removal

This issue is closely related to issue 2. To reduce gypsum scaling on critical pipelines and pumps, scale inhibitors are used. These chemical additions make it more difficult for gypsum to precipitate out of treated water and build up in the plant. Their effect on metals removal was a concern, but studies have shown no discernable effect of inhibitors on metals removal.

Issue 6: Whole Effluent Toxicity

Whole Effluent Toxicity (WET) is a measure of the total toxic effect from pollutants in treated wastewater on aquatic life. In 2010, WET testing had not yet been performed on treated water. Treated water is currently recycled in active mining operations, so it is no threat to aquatic life. Preliminary WET testing was completed during pilot testing using Horseshoe Bend water. Results showed the chronic exposure concentration with the lowest observable effect was 75% treated water mixed with 25% dilution water. More WET testing is planned.

Recommendations

EPA recommended that an additional performance test be completed prior to the 2015 five-year review to investigate all six of these issues and possible solutions.

EPA also noted that operations and maintenance at the plant are now more focused on preventative care, and operations in general have been optimized. After adjustments, treated water met all discharge standards with the exception of pH (issue 1).

In order to be protective in the long term, the various water quality issues in treated Pit water will have to be resolved before discharge to Silver Bow Creek becomes necessary. As long as Montana Resources continues active mining at the Continental Pit, no discharge is expected to occur.

Recommendations for additional performance testing will be addressed by treatability studies starting in 2016 and concluded by 2019, well before any discharge would potentially occur.

EPA determined that the ongoing remedy for the Pit is functioning as intended. When the water approaches the Critical Level, additional testing will help to further refine plant performance. The 2015 five-year review of Butte area Superfund sites will be published later in 2015, and will be available online here and on the EPA’s Butte Superfund website.

Interested citizens should contact EPA with any questions or comments regarding the 2010 or 2015 site reviews.

Water in the Berkeley Pit rising over time, 1979-2013. Photos from the Montana Bureau of Mines & Geology, Justin Ringsak, and Fritz Daily.

1982-2013: 31 years since pumps stopped

Over 31 years ago economic factors led the Atlantic-Richfield Corporation, or ARCO, now a subsidiary of British Petroleum, to cease mining operations at the Berkeley Pit in Butte, Montana. Underground mining had come to an end seven years earlier, but the underground pumps had continued to operate, pumping groundwater out from the mines and the Berkeley Pit.

The 1982 suspension of mining coincided with the stoppage of pumping, allowing groundwater to begin rising in the underground mines and eventually into the Berkeley Pit.

Water in the Berkeley Pit rising, 1979-2013. Photos from the Montana Bureau of Mines & Geology, Justin Ringsak, and Fritz Daily.
Water in the Berkeley Pit rising, 1979-2013.

With ARCO’s suspension of mining in the neighboring East Berkeley Pit (now known as the Continental Pit) on July 1, 1983, the future of mining on the Butte Hill was uncertain at best.

EPA LogoSoon after, the Berkeley Pit was classified as a federal Superfund site by the United States Environmental Protection Agency (EPA). According to the EPA, a Superfund site is an uncontrolled or abandoned place where hazardous waste is located, possibly affecting local ecosystems or people.

The end of mining at the Berkeley also marked the beginning of the Berkeley Pit lake we see today. 3,900 feet deep underground in the Kelley Mine , the pumps used to dewater the underground mines and the Berkeley Pit ran until April 23, 1982. Without pumping, the Berkeley Pit began to fill with water flowing in from both surface runoff and groundwater. Due to the natural geochemistry of the area and mining activities, the water is highly acidic and contains high concentrations of dissolved heavy metals.

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.

By 1985, ARCO had sold a portion of its holdings to Montana businessman Dennis Washington. Mining operations in the Continental Pit, as well as heap leaching of old Berkeley Pit leach pads, were resumed by his new company, Montana Resources.

Five-Year Review Report (2011) for the Berkeley Pit

Throughout 2010, the EPA interviewed local citizens and reviewed the status of Butte area Superfund sites, including the Berkeley, as part of a five-year review. The final review report, released in 2011, is available to the public and can be downloaded at the EPA Butte/Silver Bow Creek website. The sections of the report relating to the Butte Mine Flooding Operable Unit, which includes the Berkeley Pit, can be downloaded below.live streaming film Fifty Shades Darker 2017

EPA Third Five Year Review Report (2011) – Vol. 3 – Butte Mine Flooding Operable Unit (BMFOU) (644.3 KiB)

EPA Third Five Year Review Report (2011) – Vol. 3 – Butte Mine Flooding Operable Unit (BMFOU) – Appendix A: Site Photos (1.5 MiB)

EPA Third Five Year Review Report (2011) – Vol. 3 – Butte Mine Flooding Operable Unit (BMFOU) – Appendix B: Responsiveness Summary (96.3 KiB)

EPA Third Five Year Review Report (2011) – Vol. 3 – Butte Mine Flooding Operable Unit (BMFOU) – Figures (2.1 MiB)

If you would like to learn more about the review, call Nikia Greene, EPA Community Involvement Coordinator, at 1-866-457-2690, or visit the Butte EPA office at 155 West Granite (in the Courthouse).

The Butte/Silver Bow Creek Superfund Site and separate Operable Units, in the context of the greater western Montana environment that was impacted by historic mining and smelting damages. Cleanup is ongoing across the basin. Map from the EPA Five Year Review of the Butte/Silver Bow Creek Superfund Site, Part 6: Butte Priority Soils Operable Unit, Figures.

What is ‘Superfund’?

Map of Upper Clark Fork Basin Superfund environmental cleanup sites in western Montana.
Map of Upper Clark Fork Basin Superfund environmental cleanup sites in western Montana. Click on the image to view a larger version.

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.

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.

The Horseshoe Bend Water Treatment Plant, completed in 2003, captures surface water to slow the rate of fill of the Berkeley Pit lake. In the future, the plant will capture and treat water to prevent Pit water from rising further. Photo by Justin Ringsak.

Water treatment plant working as expected

The Horseshoe Bend Water Treatment Plant, completed in 2003, captures surface water to slow the rate of fill of the Berkeley Pit lake. In the future, the plant will capture and treat water to prevent Pit water from rising further. Photo by Justin Ringsak.
The Horseshoe Bend Water Treatment Plant, completed in 2003, captures surface water to slow the rate of fill of the Berkeley Pit lake. In the future, the plant will capture and treat water to prevent Pit water from rising further.

Looking northeast from the Berkeley Pit viewing stand, visitors can see one of the most important components in the future management of the Pit: the Horseshoe Bend Water Treatment Plant. Sitting on four acres near the former McQueen neighborhood, about 600 feet east of the Berkeley Pit, the treatment plant was constructed in 2002-2003. It sits on native land that is very stable, and the plant was built to withstand the maximum probable earthquake.

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.

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.

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

Under a clear EPA order, both Montana Resources and BP-ARCO are responsible for treating Berkeley Pit water. Under the Superfund law, if one company is unable to pay its share, the other company must pay all the costs of cleanup. The company paying the full cleanup costs would likely take some legal actions to recover a fair share of those costs from the other company.live streaming film Buster’s Mal Heart online

Who is responsible for treating the water?

The Atlantic Richfield Co., a subsidiary of British Petroleum (ARCO or BP-ARCO) which bought out the Anaconda Co. in 1977, and Montana Resources (MR), the company now mining in the Continental Pit adjacent to the east of the Berkeley, are responsible, along with four other entities affiliated with MR: Asarco, Inc.; AR Montana Corp.; MR Inc., and Dennis Washington. If they fail to pump and treat the water to keep levels below 5,410 feet, the U.S. government (EPA) can take over the project and charge these companies up to three times the project cost.
Superfund Operable Units in the greater Butte area. Map from the EPA Record of Decision (ROD) for the Butte/Silver Bow Creek Superfund Site (2006).

What is an ‘Operable Unit’?

An operable unit is a subsection of a larger EPA Federal Superfund site. There are four Operable Units (OUs) in the Butte mining district.

Superfund Operable Units in the greater Butte area. Map from the EPA Record of Decision (ROD) for the Butte/Silver Bow Creek Superfund Site (2006).
Superfund Operable Units in the greater Butte area. Map from the EPA Record of Decision (ROD) for the Butte/Silver Bow Creek Superfund Site (2006). Click on the image to view a larger version.
  •  The Butte Mine Flooding Operable Unit, which includes the Berkeley Pit, the hydraulically-connected underground mine workings associated with the historic East Camp and West Camp tunnel systems, associated bedrock, and alluvial aquifers. The area covers approximately 23 square miles.
  • Butte Priority Soils is a five square mile area that includes the town of Walkerville, along with the part of the Butte Hill that is north of Silver Bow Creek, west of the Berkeley Pit, and east of Big Butte. It also includes a section of land extending south from Silver Bow Creek to Timber Butte. This Operable Unit includes residential yards, mine dumps, contaminated railroad beds, and stormwater drainages on the Butte Hill and in Walkerville.
  • Silver Bow Creek/Streamside Tailings Operable Unit, which follows Silver Bow Creek from just below the historic Colorado Tailings deposit in Butte and 25 miles downstream to the Warm Springs Ponds. The area includes Silver Bow Creek itself, as well as the adjacent mining wastes deposited along the creek bank and nearby floodplain, and railroad embankments adjacent to the stream that contain mining wastes.
  • West Side Soils Operable Unit includes lands that fall outside of the Butte Priority Soils OU. There are approximately 1,500 mine waste dumps located north and west of Butte. The dumps have not been sampled. A schedule for investigating this OU and selecting a remedy has not yet been set.

There are numerous additional operable units in the greater Clark Fork River Superfund site, which stretches from Butte and 120 miles downstream to the Milltown Dam near Missoula.

The Butte/Silver Bow Creek Superfund Site and separate Operable Units, in the context of the greater western Montana environment that was impacted by historic mining and smelting damages. Cleanup is ongoing across the basin. Map from the EPA Five Year Review of the Butte/Silver Bow Creek Superfund Site, Part 6: Butte Priority Soils Operable Unit, Figures.
The Butte/Silver Bow Creek Superfund Site and separate Operable Units, in the context of the greater western Montana environment that was impacted by historic mining and smelting damages. Cleanup is ongoing across the basin. Map from the EPA Five Year Review of the Butte/Silver Bow Creek Superfund Site, Part 6: Butte Priority Soils Operable Unit, Figures. Click on the image to view a larger version.

For more information on non-Berkeley Pit Superfund sites in Butte and the Clark Fork Basin on western Montana, visit the Citizens Technical Environmental Committee (Butte CTEC) website, or the Clark Fork Watershed Education Program (CFWEP) website.