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Summitville Mine

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Site Description

The Site covers about 1,400 acres and is located in the southeastern portion of the San Juan Mountains, in the southwest corner of Rio Grande County, CO. Mining began at Summitville in the 1870s. In the 1980s, Summitville Consolidated Mining Company, Inc. (SCMCI) started large-scale surface gold mining, using the heap-leach process. Gold-bearing ore was mined, crushed and stacked or heaped on a multi-layered, lined pad. A solution of sodium cyanide was used to leach gold from the ore by sprinkling it on the heaped ore and allowing it to percolate down. Then the sodium-cyanide solution was pumped to a facility that removed the gold. These actions greatly increased the acidity and dissolved metals in the surrounding streams, damaging aquatic life. The dissolved metals include aluminum, copper, iron, manganese and zinc.

Current Site Status and Cleanup Actions to Date

  • In December 1992, the owner of the Site declared bankruptcy, and the State of Colorado requested EPA's assistance. EPA's Removal Program immediately began water treatment plant modifications to treat cyanide-contaminated leachate and acid mine drainage from numerous sources at the Site.
  • In May 1994, the Site was added to the Superfund National Priorities List (NPL).
  • EPA and its partners constructed a 90-million-gallon wastewater holding pond.
  • EPA and its partners have replanted 585-acres of mining-disturbed land.
  • EPA awarded a Technical Assistance Grant (TAG) to a group of concerned citizens to allow them to hire an independent technical advisor. The advisor reviews cleanup issues and assists the community members in contributing to the cleanup decision-making process.
  • The final site Remedial Investigation and Feasibility Study (RI/FS), led by the Colorado Department of Public Health and Environmental (CDPHE), was completed in 2001. EPA and CDPHE selected a final remedy in 2001.

Current Funding Status

  • EPA has provided more than $210 million for the Summitville project.
  • EPA has determined that this site does not pose an immediate threat to human health and will continue to monitor this site for any changes that may trigger additional action. EPA is working with its partners to better define the future actions to be taken at the Summitville site and will consider funding new construction work at this site in Fiscal Year (FY) 2006.

For more information on the projects at this site, please read the Summitville Mine Fact Sheet on the Region 8 Superfund Web site.

Key Accomplishments

  • Mine reclamation activities were completed in October 2001.
  • EPA and its partners have replanted 585-acres of mining-disturbed land, which now support plant and wildlife habitat.
  • Water quality of the Alamosa River downstream of the site has improved considerably.


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