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Timeline

1864

Gold is discovered in Butte; a mining camp is formed. [39]

 

 

1860s – 1890s

Silver production expanded and then declined when the silver market collapsed.

 

 

1870s – Current

Copper is mined in Butte.

 

 

1875 – 1955

Large-scale underground mining in Butte. [40]

 

 

1870s – 1945

This period constituted the “heyday” of milling and smelting in Butte. Silver milling boomed first, from the 1870s through about 1893. Large-scale copper smelting started around 1880, reached its peak in the 1890s, and ended in 1924. Zinc milling started small in 1905, and expanded greatly prior to and during the World War I era, closing out by 1930. Manganese was processed from 1928 through the end of World War II in 1945.[41]

 

 

1895

The Anaconda Copper Mining Company (ACMC) incorporated.

 

 

1955

ACMC changed its name to The Anaconda Company; open pit mining began in the Berkeley Pit (adjacent to the BPSOU).[42]

 

 

1971

The majority of The Anaconda Company’s global assets, in Chile and Mexico, were seized by foreign governments and nationalized.[43]

 

 

1977

Atlantic Richfield Company purchased The Anaconda Company.[44]

 

 

1980

Smelting operations in Anaconda closed.[45]

 

 

1981

The Anaconda Company merged with Atlantic Richfield.[46]

 

 

1983

Atlantic Richfield Company suspended its mining activity in Butte and offers its Butte mining business for sale. EPA placed Silver Bow Creek Site and associated areas on its national priority list of sites for investigation and remediation under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA).[47]

 

 

1985

The Butte mining business was purchased by Dennis Washington and Montana Resources Inc.[48]

 

 

1986

Mining operations resumed in the Continental Pit (formerly known as the East Berkeley Pit) under new mine ownership.[49]

 

 

1987

The Silver Bow Creek Site was modified by EPA to include the Butte area, and the site is renamed “Silver Bow Creek/Butte Area NPL Site.”[50] EPA begins conducting and ordering responsible parties to conduct strategic removals and expedited response actions to reduce potential exposure to mining waste.[51]

 

 

1988

Atlantic Richfield removes ~300,000 cubic yards of mine waste under the Walkerville Time Critical Removal Action (TCRA).[52]

 

 

1989

Atlantic Richfield completes the Timber Butte TCRA, addressing 40,000 cubic yards of contaminated soil.[53]

 

 

1990

Remedial investigation and feasibility study investigations begin in the 1990s.[54] Thirty waste dumps are addressed by Atlantic Richfield under the Butte Priority Soils TCRA,[55] resulting in removal or remediation of 100,000 cubic yards of waste.

 

 

1992

Atlantic Richfield removes and consolidates ~40,000 cubic yards of impacted materials under the Colorado Smelter TCRA. The Lower Area One Expedited Response Action (ERA)[56] is initiated by Atlantic Richfield, eventually removing over 1 million cubic yards of accessible mine waste and tailings along Silver Bow Creek.

A consent order with EPA is signed by Atlantic Richfield and other potentially responsible parties (PRPs) to conduct a Remedial Investigation/Feasibility Study (RI/FS).[57]

 

 

1994

Walkerville TCRA II is completed by Atlantic Richfield,[58] addressing 12 additional waste dumps. The Butte Priority Soils ERA for Residential Soils/Source areas begins, leading to ongoing metal abatement for contaminated residential yards and attics under what is now referred to as the Residential Metals Abatement Program (RMAP).[59]

 

 

1997

Atlantic Richfield begins work under the Stormwater TCRA[60] to control stormwater flow, minimize erosion, and reduce transport of contaminated sediment to Silver Bow Creek. Work included reclamation of the Alice Mine dump, reclaiming ~ 2,000,000 cubic yards of contaminated soil and waste rock.

 

 

1998

Phase I of the BPSOU Remedial Investigation and Feasibility Study (RI/FS) is completed.[61] Atlantic Richfield enters into agreements with the U.S. EPA, State of Montana and other trustees on certain natural resource damages and remediation claims relating to Clark Fork River Basin sites.

 

 

1999

The Court approves settlements among Atlantic Richfield, the State, and the U.S. to resolve: some claims for natural resource damages and restoration activities in portions of the Clark Fork Basin, claims for remediation of most of Silver Bow Creek, and past costs incurred during litigation.[62] Further information can be found on the Administrative and Judicial Proceedings webpage.

 

 

2001

Atlantic Richfield opens the Copper Mountain Sports and Recreation Complex to the public.[63]

 

 

2002

Phase II of the BPSOU RI/FS is completed.[64]

 

 

2003

Atlantic Richfield begins construction of the Metro Storm Drain (MSD) subdrain system,[65] now referred to as “upper Silver Bow Creek,” that captures contaminated groundwater beneath the upper Silver Bow Creek corridor for treatment at the Butte Treatment Lagoons system

 

 

2005

The remainder of the BPSOU RI/FS is completed.[66] EPA releases proposed plan for remediation in the Butte and Walkerville areas.

 

 

2006

U.S. EPA issues a Record of Decision (ROD) containing the selected, final remedy for BPSOU.[67] Butte-Silver Bow County (BSB) and Atlantic Richfield[68] reach an agreement that provides funding to BSB to complete certain portions of the remedy. The Butte Historic Landmark District is expanded. Design and construction of the final BPSOU remedy begin.[69] The Butte lead abatement program is re-named the “Residential Metals Abatement Program,” building on the multi-pathway program initiated by U.S. EPA with funding from Atlantic Richfield in 1994, in cooperation with Montana DEQ and Butte-Silver Bow County.[70]

Butte Reclamation Evaluation Program begins.[71]

 

 

2008

Upgrades of the subgrade vault pumping system and control building of the MSD subdrain system are completed by Atlantic Richfield.[72]

The State, the U.S., and Atlantic Richfield reach a final settlement for remediation of the upper Clark Fork River site and settle all remaining State claims for natural resource damages and restoration costs for Butte Area One, the Smelter Hill Uplands, and the upper Clark Fork River.[73]

 

 

2009

Atlantic Richfield begins cleanup and redevelopment construction of Mountain Con Mine Yard.[74]

 

 

2010

Atlantic Richfield completes the Granite Mountain Memorial[75] and begins Silver Bow Creek stream bank and floodplain removal near the confluence with Blacktail Creek.

Atlantic Richfield expands groundwater capture system of Lower Area One[76] during the Butte Reduction Works Open Area Excavation project.

EPA reports that the majority of capping is complete.[77]

 

 

2011

EPA issues a BPSOU Unilateral Administrative Order to Atlantic Richfield and Butte-Silver Bow, with additional remedy analyses and requirements that are needed to complete the 2006 BPSOU ROD remedy.[78] Atlantic Richfield begins to upgrade the Butte Treatment Lagoons and West Camp Pump Station,[79] modernizing the groundwater collection and treatment system at Lower Area One.

 

 

2012

Atlantic Richfield opens Foreman’s Park[80] and recreation area at the Mountain Con Mine Yard and completes a one-mile extension of Mine Yard and Butte Hill Trail system.

 

 

2014

Atlantic Richfield begins the Lower Area One Surface Enhancements[81] to improve vegetative cover throughout Lower Area One.

 

 

2015

Atlantic Richfield completes demolition and reclamation of the former Wetland Demonstration Area[82], covering approximately eight acres in the center of Butte.

 

 

2016

Atlantic Richfield begins reclamation and preservation of the historic Lexington Hoist House and Mine Yard.[83]

 

 

2018

EPA releases potential concepts for modifications to the 2006 BPSOU ROD remedy for public review and comment. Details can be found on the Completing the remedy page of this website.[84]

 

 

2019

April 11—EPA publishes an amended proposed remedy plan for BPSOU, for public review and comment. The comment period closed on July 11, 2019.

 

 

2020

February 4—US EPA releases an amended Record of Decision for the Butte Priority Soils Operable Unit and portions of the Butte Area site.

February 13—US EPA, the State of Montana, the consolidated City and County government of Butte-Silver Bow (BSB) and Atlantic Richfield Company announce a proposed partial Consent Decree for the Butte Priority Soils site.

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