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Central City/Clear Creek (Big Five Mine, Chase Gulch #2)

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Printable Version (PDF) (44 K, 2 pp)

Site Description

The Central City/Clear Creek site is a 400-square-mile watershed that extends from the Continental Divide east to Denver, CO. Mining wastes were disposed of in Clear Creek contaminating it with zinc and cadmium. Clear Creek and its tributaries are used in whole or in part as a drinking water supply by several municipalities including Georgetown, Idaho Springs, Black Hawk, Golden, Westminster, Thornton, and Arvada. Water from Clear Creek is also used for agriculture and recreation.

Current Site Status and Cleanup Actions to Date

  • In 1983, EPA placed the Central City/Clear Creek site on the National Priorities List (NPL).
  • Colorado Department of Public Health and Environment (CDPHE) is the lead for the cleanup, with EPA working in collaboration.
  • Casino developers in Central City and Black Hawk have capped or removed a number of mine waste piles as part of the cleanup.
  • CDPHE completed a cleanup at the Argo Mill waste pile that included storm water controls and stream bank restoration.
  • The cleanup plan included a voluntary program to test water from private wells. Free bottled water is provided to well owners who volunteered for testing and whose wells had contaminated water.
  • To date, a number of mining waste and tails piles have been excavated (PDF) (530 K, 2 pp) and the contaminated materials removed, or capped (PDF) (526 K, 2 pp).
  • Records of Decision (RODs) for the first two cleanup projects (known as Operable Units (OUs) 1 and 2), identified five discharging mine tunnels and the five tailings and mine waste piles associated with those tunnels for remedial action.
  • The ROD for the third cleanup project (OU3) modified those decisions and identified six discharging mine tunnels and seventeen tailings and waste piles for interim or final action. EPA will have to cleanup waste piles that range in size from 10,000 to 340,600 cubic yards.
  • The ROD for OU4 was created to investigate contamination associated with the North Clear Creek tributary to Clear Creek.

Current Funding Status

  • Work on the design phase for the Big Five Mine Portal, and the Chase Gulch #2 Mine Waste Pile areas covered under OU2 and OU3 was completed during Fiscal Year (FY) 2005. Construction work at these three areas was started from funding available through the existing State Cooperative Agreements with the State of Colorado for these areas; therefore, additional funds were not needed.
  • The Big Five Mine Portal (OU2) project construction completion is expected in early FY 2006.
  • The Chase Gulch #2 Mine Waste Pile (OU3) project construction completion is expected in early FY 2006.

For more information on the projects at this site, please read the Central City/Clear Creek Fact Sheet on the Region 8 Superfund Web site.

Key Accomplishments

  • Work on the design phase for the Big Five Mine Portal (OU2), and the Chase Gulch #2 Mine Waste Pile (OU3) was completed during FY 2005.
  • Casino developers in Central City and Black Hawk have capped or removed a number of mine waste piles as part of the cleanup.
  • CDPHE completed a cleanup at the Argo Mill waste pile that included storm water controls and stream bank restoration.
  • The cleanup plan included a voluntary program to test water from private wells. Bottled water is being provided free to those well owners who volunteered for testing and whose wells had contaminated water.

 

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