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Upper Tenmile Creek
Helena, Montana

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Site Description

The Upper Tenmile Creek Mining Area site is located in the Rimini Mining District, southwest of Helena, Lewis and Clark County, MT. It consists of many abandoned and inactive hard rock mine sites that produced gold, lead, zinc, and copper. Mining began in the Rimini Mining District before 1870 and continued through the 1920s. The site boundary includes the drainage basin of Tenmile Creek upstream of the Helena Water Treatment Plant. It also includes tributaries that supply water to the plant's five intake pipelines. Contaminants of concern are heavy metals, primarily lead, copper and zinc, as well as arsenic.

Current Site Status and Cleanup Actions to Date

  • In 2000 and 2001, EPA conducted a cleanup investigation and feasibility study that showed high levels of arsenic and/or lead in most yards in the community of Rimini and some in the nearby Landmark subdivision. The investigation also found high levels of these contaminants at 70 high priority mine sites. Private water wells in Rimini are also contaminated.
  • In 2002, EPA removed high-priority mine waste and provided in-home water treatment systems. After evaluating cleanup options, EPA selected a long-term cleanup plan that included removal of contaminated soils and mine waste.
  • EPA cleaned up Landmark yards and the Lee Mountain Mine in 2003-2004.
  • In 2005, the Agency began construction of the Rimini wastewater system.
  • In 2006 EPA conducted cleanups of Rimini yards (where accessible), cleaned up the Lee Mountain staging area and undertook reclamation improvements to the Luttrell Repository, a 100,000-cubic-yard repository of mine wastes.
  • In 2008 EPA completed a Record of Decision (ROD) amendment.
  • EPA completed a five-year review of the site in 2008. The review found that the cleanup is being conducted according to the site cleanup plan and that the cleanup is expected to be protective when complete.

Current Funding Status

  • Cleanup activities addressing the cleanup of mine waste on Rimini roads were not funded in Fiscal Year 2008.
  • To date, EPA has obligated $32 million for cleanup activities at this site.

For more information on this site, please read the Upper Tenmile Creek site fact sheet (http://www.epa.gov/region08/superfund/mt/upper_ten/index.html#5) on the Region 8 Superfund web site.

Key Accomplishments

  • Removed high-priority mine waste and provided in-home water treatment systems in 2002
  • Cleaned up Landmark yards and the Lee Mountain Mine in 2003-2004
  • Completed five-year review of the site in 2008


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