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Region 8

Serving Colorado, Montana, North Dakota, South Dakota, Utah, Wyoming and 27 Tribal Nations

Superfund Program

   

National Information
Regional Information
Site Information
National Priorities List (NPL) History

Proposed Date
12/30/1982

Final Date
9/8/1983

Central City/ Clear Creek

Central City Clear Creek site map
Site Type: Final NPL
City: Idaho Springs
County: Clear Creek
Street Address: Near Town
Zip Code: 80452
EPA ID#: COD980717557
Site ID#: 0800257
Site Aliases: Argo Tunnel, Five Mile Tunnel, Central City Mining District, Quartz Hill Tunnel, National Tunnel, Gregory Incline, Newhouse Tunnel
Congressional District(s): 02

The Clear Creek/Central City Site has received up to $5 million in new funding through the American Recovery and Reinvestment Act of 2009. The new money will accelerate the cleanup of the 400-square-mile Clear Creek watershed that is impacted by wastes from historic mining activities. Improvements will include the consolidation and capping of mine waste piles, sediment control and water treatment to mitigate heavy metals impacts to Clear Creek, a tributary of the South Platte River. Work at the site will also reduce metals entering the watershed which supplies water to Denver-area residents.

 What's New?

2008 Construction Activities

Church Placer Mine Waste Repository:

  • The State acquired the Church Placer property on October 30, 2008.
  • The new access road on the property is complete.
  • Three sediment retention ponds have been constructed to control surface water run-off and to trap sediment.
  • Construction of run-on control ditches and installation of culverts is complete.
  • The entire property has been graded to remove erosion cuts and rills, remove debris, and a soil cover has been placed and hydro-seeded to stabilize this year's work.
  • The consolidation area where sediment will be placed is complete. Sediment produced from the Nevada Gulch and Russell Gulch sediment dams, sediment retention ponds and check dams will be placed there.
  • A rock cover has been placed on the steep slopes of the two heap leach pads.
  • Rock used for this project came from a Colorado Department of Transportation (CDOT) Highway 119 project.

Nevada Gulch:

  • A run-off control ditch was completed for the Keystone waste rock pile.
  • Two check dams were completed in the vicinity of the American Flag waste rock pile.
  • Near Nevadaville, part of the Nevada Gulch drainage ditch was reconstructed and repairs were made on an existing ditch.

Pittsburg Mine Tailings Pile & Adjacent Channel:

  • In the Russell Gulch channel, workers removed eroded tailings, placing them on stable areas of the Pittsburg and Mattie May mine waste piles.
  • The Russell Gulch channel was reconstructed and four rock drop structures were installed.
  • At the Pittsburgh Mine, two waste rock and tailings piles were re-graded and covered with rock generated from a CDOT Highway 119 project.

Baltimore, Alva Adams:

  • Tailings piles were re-graded or moved to the Mattie May Mine and capped with a rock cover.
  • To prevent erosion, riprap was placed at the toe of the piles adjacent to Russell Gulch.
  • A run-on control ditch was constructed above the Baltimore pile.

South Willis Gulch:

  • Construction of four check dams

Golden Gilpin Mill Site:

  • Controlled contamination at the mill site by capping and revegetating portions of the waste pile and stabilizing the adjacent bank of North Clear Creek.

2008 Design Activities:

National Tunnel Passive Treatment System:

  • Testing of various sulfate reducing bioreactors continued. A summary report of the pilot study was finalized.

National Tunnel Conveyance System:

  • A preliminary design of the piping system to deliver the tunnel discharge to the passive treatment system was completed.

Waste Rock, Sediment Control Projects and On-site Mine Waste Repository:

  • The design for Phase II of this project was developed. This project is being constructed in three phases over three years.

North Clear Creek Improvements:

  • The state and EPA joined with the CDOT to mitigate mining impacts along the mile downstream of Black Hawk, restore fish and wildlife habitat and improve transportation along the State Highway 119 corridor. Coordination and plans for teaming were developed in order to implement the Superfund and highway projects in an efficient manner.

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 Site Description

The Central City /Clear Creek site (the "Site") is a 400-square-mile watershed extending from the Continental Divide east to the Denver metropolitan area. Popular for activities like fishing, rafting, kayaking and gold panning, the Site also serves as a drinking water source for more than 50,000 people in the northwest Denver Metro area. Historic gold mining and mine wastes left behind in the Clear Creek basin contaminated the watershed.

Abandoned mines along Clear Creek produce acidic, metal-laden water that drains into the creek. Piles of mine tailings located along or near the creek's bank erode or leach metals into the water. Because these mine wastes are scattered throughout the Clear Creek basin this Site has been identified as a study area where efforts are focused on water quality goals rather than individual tasks. Local, state and federal agencies, industry and concerned citizens are working together to improve water quality in the watershed.


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 Site Risk

Media Affected Contaminants Source of Contamination
Soil, surface water, leachate, ground water, liquid waste Heavy metals like
zinc, copper, manganese, cadmium, lead and arsenic
 Mining and milling operations within a watershed

EPA and Colorado Department of Public Health and Environment (CDPHE) assessed potential impacts to human health and the environment from mine waste piles and tunnel discharges.

The primary contaminants of concern (COC) for humans at this Site are arsenic and lead. Health risks to humans could result from long-term drinking of ground water with high concentrations of these metals, incidental ingestion of tailings and waste rock, and/or inhalation of airborne dust.

Contaminants of concern for aquatic life include zinc, copper, cadmium, and manganese. These metals are found in surface water and primarily affect trout and aquatic insects, as well as aquatic and riparian vegetation.

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 Cleanup Progress

2007

Phase 1 Operable Unit 4 work included erosion-protection measures and sediment detention basins. Erosion control measures included run-on and run-off ditches and re-grading of steep or eroding slopes. The following projects were completed:

  • Anchor
  • Silver Dollar
  • Powers
  • Gregory Gulch #3
  • Lower Nevada Gulch Sediment Retention Dam
  • Russell Gulch Sediment Retention Basin

EPA and CDPHE formed partnerships to complete two separate projects:

  • The Colorado School of Mines joined efforts to implement a pilot project testing of various passive systems to treat water from the National Tunnel. Systems known as "sulfate-reducing bioreactors" were used.
  • Black Hawk/Central City Sanitation District along with CDPHE and EPA constructed a wetlands project to filter and remove metals from North Clear Creek water.

2006

  • The Record of Decision (ROD) for Operable Units 3 & 4 was amended to add an on-site mine waste repository.
  • In an effort to address significant sources of metals contamination to the main stem of Clear Creek, structures to pipe water from both Virginia Canyon and the Big 5 Tunnel to the Argo Water Treatment Facility were built.

2005

  • The Argo Water Treatment Facility began using hydrated lime in its treatment process of metals-laden water from the Argo Tunnel.
  • Design work for the reclamation of the Golden Gilpin Mill was completed.
  • Construction of the cap for the Chase Gulch #2 mine waste pile was completed.
  • CDPHE, CDOT, EPA and the city of Idaho Springs worked collaboratively to design and construct a conveyance system to take the water from the Big 5 Tunnel drainage and pond to the Argo Water Treatment Facility. As part of this project the Big 5 Pond has been drained, filled and capped.
  • A cutoff wall and sediment basins were constructed along with general storm water management maintenance the county needed in Virginia Canyon to assist with the collection of the metals-laden surface and ground water.
  • The ROD for Operable Unit 4 (OU4) was signed Sept. 29, 2004 for the cleanup of North Fork of Clear Creek and its tributaries as well as Quartz Hill, Gregory Incline and National Tunnel mine discharges.

2004

  • The Five Year Review and update of the Community Involvement Plan were completed.
  • A public meeting was held to discuss the proposed cleanup plan and preferred alternative for OU4. Comments were accepted from the public about the cleanup alternatives and the OU4 ROD was finalized in September.
  • Work was completed in Virginia Canyon which included removing mine waste piles from the Two Brothers Mine, the Little #6, and collecting ground water to divert to the Argo water treatment plant.
  • The Clear Creek Watershed Foundation completed cleanup of waste piles at the Leavenworth, Sydney and Dibbens mines.

2003-2000

  • In 2003, an amendment to the ROD for OU3 to change the remedial action at the Burleigh Tunnel to a no-action response was completed.
  • In 2000, EPA and CDPHE began looking at locations for use as an on-site mine waste repository. Three locations were considered: the Gem/Franklin in Clear Creek County, the Glory Hole and the Druid/Church Placer, both located in Gilpin County.

Pre-2000

  • In 1999, CDPHE began high-flow and low-flow surface water monitoring on Clear Creek below the Burleigh Tunnel.
  • During 1998, one of the wetland components at OU 3 was decommissioned and the other component operated until 1999.
  • April 1998, the Argo Water Treatment Plant was completed and began operation, removing about 99% of the metals from the mine water.
  • August 1993, pursuant to the Operable Unit 3 ROD: a passive treatment wetland was constructed as a pilot scale demonstration project at the portal of the Burleigh Tunnel.
  • Cleanups of numerous tailings and waste rock piles occurred during the 1990s.
  • The Operable Unit 3 ROD was signed Sept. 30, 1991.

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 Community Involvement

Team members regularly meet with local elected officials, groups like the Upper Clear Creek Watershed Association, Black Hawk Rotary Club and individuals as needed. It is important to reach out to communities to understand any concerns the community may have as work progresses.

CDPHE and EPA have provided the community with information about the work being done by using fact sheets, public notices and press releases in local papers, a community involvement plan, maintaining an information repository, public meetings, individual or small group informal meetings, and occasional e-mails.

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 Site Documents

Note: most of the following documents are VERY LARGE PDF FILES
About PDF files

Explanation of Significant Differences in the Big Five Tunnel Discharge (PDF, 20 pages, 718 kB)

2008 Fact Sheet (PDF, 6 pages, 356 kB)

Proposed plan to amend the Records of Decision for OU3 and OU4 to add an on-site repository (PDF, 9 pages, 91 kB)

Records of Decision List (ROD List)

Amendments to Records of Decision (RODs)

Five-Year Review List

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 Contacts

State of Colorado

Ron Abel, State Project Manager
Colorado Department of Public Health and Environment
HMWMD-B2
4300 Cherry Creek Drive South B2
Denver, CO 80246
FAX: (303) 759-5355
(303) 692-3381
ron.abel@state.co.us

Warren Smith
Community Involvement Manager
Colorado Department of Public Health and Environment
HMWMD-B2
4300 Cherry Creek Drive South B2
Denver, CO 80246
FAX: (303) 759-5355
(303) 692-3373
warren.smith@state.co.us

U.S. EPA

Mike Holmes, Remedial Project Manager
U.S. Environmental Protection Agency
1595 Wynkoop Street
Denver, CO 80202-1129
FAX: (303) 312-6961
(303) 312-6607
holmes.michael@epa.gov

Peggy Linn, Community Involvement Coordinator
U.S. Environmental Protection Agency
1595 Wynkoop Street
Denver, CO 80202-1129
FAX: (303) 312-6961
(303) 312-6622
linn.peggy@epa.gov

Toll Free 800-227-8917

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