Montana Resources and Atlantic Richfield are currently funding a Montana Tech graduate student to develop a remote system to sample Pit water quality. The student will review options to collect the required data, including aerial or water-based drones that can be operated from the shore of the Pit.
Due to the size of the Pit and the need to collect samples from locations throughout it, the ability to communicate with the drone at a distance of up to 2 miles is essential. Work began during the summer of 2015 and will continue through the 2015-2016 academic year and summer 2016, with final testing during the June and July, and collection of Pit samples by August 2016.
Electrical engineering assistant professor Bryce Hill is supervising the project. He said the device could potentially be used for applications beyond the Berkeley Pit.
The guiding documents for Pit management require ongoing assessment and evaluation of the Horseshoe Bend Water Treatment Plant and the technology used to treat contaminated Pit water until several years prior to full-scale implementation. That implementation is required when water levels at any monitoring compliance point reach the Critical Level of 5,410 feet above sea level.
A review of treatment technologies is required 4 years before any compliance point is projected to reach the Critical Level. Current projections show that the Critical Level will be reached in 2023; therefore the technology review will start in 2017 and must be completed by 2019. AR and Montana Resources are already evaluating treatment alternatives, and this work will continue through 2017. This includes treatability studies and testing on the expected quantity and quality of contaminated water. Construction upgrades are scheduled for 2019 through 2021, with upgrades completed at least 2 years before the Critical Level is reached.
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
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.
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.
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.
There are two reasons why the Pit will never overflow. First, the 1994 Record of Decision and 2002 Consent Decree established the maximum level that the water will be allowed to reach to make sure the Berkeley Pit is lowest point in the cone of depression (see center graphic). Wells to monitor water levels have been set up. Failure to keep the water below the 5410′ elevation would result in steep fines for BP/Atlantic Richfield and Montana Resources. Second, the Horseshoe Bend Water Treatment Plant is already in-place and operating. It has the capacity (7 Million Gallons per Day) to treat water from the Berkeley Pit, when it becomes necessary. This will ensure the water level remains below 5,410′.
The Horseshoe Bend Water Treatment Plant will empty the Berkeley Pit.
In the 1994 Record of Decision, the agencies decided that it would be unfeasible for the Potentially Responsible Parties (PRP’s) to ever completely empty the Berkeley Pit. The remedy selected for the Berkeley Pit is to treat all water inflows to maintain the level below 5,410′ above sea level.
Congress is cutting the national Superfund program and the operation of the Horseshoe Bend Water treatment Plant will be discontinued.
The ‘Butte Mine Flooding Superfund Site’ is the responsibility of BP/Atlantic Richfield and Montana Resources. Thus, the plant will not be affected by any changes to the EPA’s Superfund Program. The legally binding Consent Decree, which was signed by the responsible parties in 2002, established the financial commitment to operate and maintain the water treatment plant in perpetuity.
On August 14, 2002, U.S. District Judge Sam E. Haddon signed the Mine Flooding Consent Decree between the Atlantic Richfield Company (Arco), the Montana Resources Group (MR), the U.S. EPA, the State of Montana (DEQ) and the U.S. Department of Justice.
The Consent Decree was released for public review on March 26, 2002, with a May 4 deadline to submit public comments to the federal court. EPA and DEQ reviewed the comments submitted and in late July 2002, the Agencies submitted a report to the federal court recommending that none of the public comments warranted any changes in the Decree. Subsequently, Judge Haddon approved and signed the Consent Decree as originally drafted.
With the Consent Decree lodged in federal court as a legally binding agreement, Arco and MR proceeded with plans to build the Horseshoe Bend Water Treatment Plant. The companies are also obligated to provide annual financial statements to document their capability to pay all costs to operate and maintain the facility – including sludge disposal – in perpetuity.
The Decree also requires Arco and MR to reimburse EPA and DEQ for past costs and pay now for future oversight costs. Other obligations are to enhance the waterfowl protection program at the Berkeley Pit, to establish a groundwater control area surrounding the Berkeley, to fund the Montana Bureau of Mines and Geology to continue the mine flooding monitoring program, and to fund public education (e.g., PITWATCH).
In March 2002, the Atlantic Richfield Company (ARCO) and Montana Resources (MR) agreed to sign a Consent Decree, a legally binding document that will be entered in federal court. The Consent Decree requires these companies to reimburse EPA and DEQ for past costs, and pay now for future oversight costs. It also guarantees that these companies will perform a number of tasks and provide financial assurances to pay all costs to complete the required work.
Most importantly, the Consent Decree sets a firm schedule for Arco and MR to build a water treatment facility, and confirms their obligations to operate and maintain the facility – including sludge disposal – in perpetuity. Also included in the Consent Decree are commitments to enhance the waterfowl protection program at the Berkeley Pit, to establish a groundwater control area surrounding the Berkeley, to fund the Montana Bureau of Mines and Geology (through the EPA and DEQ) to continue the mine flooding monitoring program, and to fund public education activities (e.g., PITWATCH).
As part of the process, ten changes were made to the Record of Decision (1994). For example, changes were made to recognize new stream and discharge standards for the treated water, to allow Continental Pit water treatment in the Horseshoe Bend plant, and to allow sludge disposal in the Berkeley Pit. Another change eliminates the requirement to reevaluate treatment technologies when the water level in the Pit reaches the 5,260′ level, since the treatment plant will already be built. The Consent Decree also clarifies which cleanup tasks will be done under the Superfund program and which will be done under the State’s active mine permit reclamation program.
The Consent Decree was released on March 26, 2002 for public comment until May 4, and is expected to be finalized thereafter. Contact the Committee with any questions.