Butte Natural Resource Damage Restoration Council (BNRC)
Lower Area One (LAO) is a very active segment of the broader Butte Area One Operable Unit, which has recently received attention after funds from the 2008 Consent Decree between the State of Montana and ARCO were allocated to restoration in the unit. The Butte Natural Resource Damage Restoration Council (BNRC) provides recommendations to the Governor on how to spend the $28 million dedicated to restoration of the Butte Area One Site, which encompasses the Lower Area One treatment complex and historic Silver Bow Creek back up to the edge of the Berkeley Pit.
The wastes in this area from mining-related operations have injured the area’s surface and groundwater resources. Butte Area One and LAO are a part of the larger Butte Priority Soils Operable Unit (BPSOU),
The extent of alluvial groundwater injury is about 560 acres. The EPA Record of Decision, issued in 2006, is being implemented. Without effective remediation or removal of the sources of contamination, this area will continue to be contaminated for thousands of years. In addition, contaminated groundwater enters Silver Bow Creek from the alluvial aquifer, and contaminated surface water enters Silver Bow Creek from storm water runoff flowing across mine dumps and soils within the BPSOU. This contaminated water adversely affects water quality and aquatic life in Silver Bow Creek. The $28 million allocated to this site under the 2008 settlement is expected, along with the EPA remedy, to address this contamination.
In March 2012, the Governor approved the Butte Area One Final Restoration Process Planning Document . This document specifies the procedures, criteria, and schedule for the development of a restoration plan for Butte Area One, scheduled to be completed by the end of 2012. The Butte Natural Resource Damage Restoration Council (BNRC) developed this process plan, with assistance from the Natural Resource Damage Program. The plan and related BNRC documents are available to download below, or via the Superfund Library.
For more information on the BNRC, NRDP, and related restoration planning documents, contact Pat Cunneen at 406-533-6882 or e-mail at PCunneen@mt.gov.
Lower Area One Cleanup
EPA conducted an Expedited Response Action for Lower Area One, which lies in urban Butte and includes portions of Silver Bow Creek, as well as groundwater treatment ponds at the bottom of the Butte hill at the west side of the Butte urban area, the “slag canyon” of Silver Bow Creek, and surrounding areas.
Removal of Department of Defense manganese stockpiles (approximately 245,000 tons) at the site occurred in the summer and fall of 1992. Removal of mine tailings (from the old Colorado and Butte Reduction Works smelters) began in the spring of 1993 and was completed in 1997. An estimated 1.4 million cubic yards of tailings was removed.
The tailings were originally transported by rail to the Opportunity Ponds (also known as the BP-ARCO Waste Repository) near Anaconda, but in the final year, the tailings were transported by truck to the Clark Tailings in Butte, and the closure of the Clark Tailings was integrated with the closure of the old Butte Silver Bow landfill.
Cleanup Phase I (1993 to 1998) involved removing the Colorado Tailings that contained heavy metals and then reconstructing the Silver Bow Creek channel. As per the ROD Fact Sheet for the site, contaminated sediment was excavated from Silver Bow Creek between the confluence of Silver Bow Creek (also referred to as the Metro Storm Drain, or MSD) and Blacktail Creek down to the reconstructed stream channel in Lower Area One.
Removal of sediments minimizes contamination entering nearby surface water. About 1.2 million cubic yards of tailings (approximately 1.2 million pick-up loads) were moved and placed on the Clark Tailings, then capped with clean material.
The Copper Mountain Park was built on the site as a final cap. Large volumes of clean soil were brought back to replace the Colorado Tailings before the new Silver Bow Creek channel was constructed. The area was revegetated with native grasses, shrubs and trees.
Phase II (2001—present) involved the construction of the Butte Treatment Lagoons and a ground water collection system. The groundwater collection system includes the approximate historic Silver Bow Creek channel (also called the Metro Storm Drain, or MSD) and runs from the corner of Continental Avenue and Texas Avenue in Butte to just east of Montana Street, where it joins Blacktail Creek.
Groundwater is collected from the West Camp Underground System and Lower Area One. The Butte Treatment Lagoons treat approximately 1,200 gallons of water per minute. As noted in the ROD Fact Sheet, contaminated groundwater associated with buried waste in Lower Area One and Silver Bow Creek/MSD is captured and routed to the existing treatment lagoons at Lower Area One for treatment on a probationary basis. The five-year probationary period will allow time to address operation and maintenance issues. If these issues cannot be addressed, a conventional lime treatment facility will be built. Groundwater will be thoroughly and carefully monitored.
The treatment system is a two part process. Lime is added to the groundwater, causing the heavy metals to drop out of the water. Then the water travels through a series of wetlands to meet State of Montana water quality standards.
Starting in fall 2010, EPA and BP-ARCO began upgrading the existing Butte Treatment Lagoons. Full details are discussed in this EPA Bulletin from October 2010. Work there is ongoing.