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National Information |
National Priorities List (NPL) HistoryProposed Date Final Date |
Superfund Program
Central City/Clear Creek
|
Site Type: Final NPL |
What's New
- October 2007 Phase 1 Operable Unit 4 erosion protection measures completed at four mine waste piles. Erosion control work includes run-on and run-off ditches and regrading of steep or eroding slopes. Work was completed at the following locations:
- Anchor
- Silver Dollar
- Powers
- Gregory Gulch #3
- Summer 2007 work completed on the Phase I Operable Unit 4 sediment control measure to reduce the amount of mine waste eroding into the tributaries of Clear Creek. The following projects were completed:
- Lower Nevada Gulch Sediment Retention Dam
- Russell Gulch Sediment Retention Basin
- During 2007 the Colorado School of Mines, EPA and CDPHE joined efforts to implement a pilot project testing various passive systems to treat water from the National Tunnel. Systems known as "sulfate-reducing bioreactors" are being used.
- In 2007, Black Hawk/Central City Sanitation District teamed with CDPHE and EPA to develop a wetlands project which will filter and remove metals from North Clear Creek Water.
- Throughout 2007, CDPHE and EPA continued to pursue options for locating a mine waste repository.
Site Description
Clear Creek 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, it also serves as a drinking water source for over 650,000 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-rich water that drains
into the river. Piles of mine tailings located along or near the river'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.
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 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 effect trout,
aquatic insects, as well as aquatic and riparian vegetation.
Cleanup Progress
- June 2006 a proposed plan to amend the Record of Decision for Operable Units 3 & 4 to add an on-site mine waste repository was presented to the public in Gilpin and Clear Creek counties.
- In 2006 water from both the Virginia Canyon and Big 5 Tunnel projects is being sent to the Argo Water Treatment Facility. These two projects complete efforts to address significant sources of metals contamination to the main stem of Clear Creek
- November 2005 the Argo Water Treatment Facility in Idaho Springs switched from using sodium hydroxide to hydrated lime in its treatment process of metals-laden water from the Argo Tunnel.
- September 2005 design work for the reclamation of the Golden Gilpin Mill was completed.
- November 2005 the Argo Water Treatment Facility in Idaho Springs switched from using sodium hydroxide to hydrated lime in its treatment process of metals-laden water from the Argo Tunnel.
- During 2005, the design and construction for capping the Chase Gulch #2 mine waste pile was completed.
- Summer 2005 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.
- Summer 2005 construction of 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.
- Record of Decision for Operable Unit 4 (OU4) was signed September 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.
- In September 2004, the Five Year Review and update of the Community Involvement Plan were completed.
- August 2004 a public meeting was held to discuss the proposed cleanup plan for OU4. This included the preferred alternative. Comments were accepted from the public about the cleanup alternatives.
- In 2004 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.
- During 2004, the Clear Creek Watershed Foundation completed cleanup of waste piles at the Leavenworth, Sydney, and Dibbens mines.
- 2003 a proposed plan to amend the ROD for OU3 changing the work at the Burleigh Tunnel to be a no action response.
- In 2000, EPA and CDPHE agreed to begin looking at locations for use as an on-site mine waste repository. This repository would be used for mine waste piles located throughout the watershed and for the metals solids from the water treatment facilities located in either Clear Creek or Gilpin counties. Three locations were considered: the Gem/Franklin in Clear Creek County, the Glory Hole and the Druid/Church Placer both located in Gilpin County.
- In 1999, CDPHE began high-flow and low-flow surface water monitoring on Clear Creek below the Burleigh Tunnel.
- 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 is completed, removing about 99% of the metals from the mine water.
- August 1993, pursuant to the Operable Unit 3 Record of Decision: 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 1990's.
- September 30, 1991, the Record of Decision was signed for Operable Unit 3.
- September 8, 1983, Central City/Clear Creek is listed on the NPL site list.
- Explanation of Significant Differences, Argo & Big Five Mine Waste Sites (PDF, 1 MB)
- Record of Decision (ROD) for Operable Unit 4 (OU4), North Fork Basin - September 29, 2004 (PDF, 9 MB)
- Record of Decision (ROD) for Operable Unit 3 (OU3), Burleigh Tunnel Discharge - June 5, 2002 (PDF, 1 MB)
- Amendment to Operable Unit 3 (OU3) ROD for the Burleigh Tunnel Discharge - June 5, 2003 (1 MB, PDF)
- Amendment to Operable Unit 3 (OU3) and Operable Unit 4 (OU4) Records of Decision for the addition of an on-site repository
- Five-Year Review Report, Third for Clear Creek/Central City Superfund Site - September 29, 2004 (5 MB, PDF)
- Five-Year Review Annual Update December 2007 (PDF, 42 K, 4pp)
Summer 2005
Community Involvement
Community involvement efforts at this site include frequent meetings with the Upper Clear Creek Watershed Association and individual members or stakeholders to obtain input in shaping the scope of work and to understand the community concerns as work progresses. Other groups CDPHE and EPA obtain input from include the Black Hawk Rotary Club, Clear Creek County and Gilpin County Commissioners and the Golden City Council.
Agencies found the Clear Creek Watershed Advisory Group a valuable tool in advising the agencies on local interests, priorities and opinions. This group received partial funding by an EPA technical assistance grant. Their final report was issued in January 2001.
Other means of communicating with the public include using fact sheets, public
notices and press releases. Fact Sheets are used to explain documents like
proposed cleanup plans and the preferred alternative, to keep the public updated
on current work efforts, and public notices inform the public where records
are kept in the different communities.
Site Documents
Note: most of the following documents are VERY LARGE PDF FILESAbout PDF files
Evaluation of Significant Differences in the Big Five Tunnel Discharge (PDF, 20 pages, 718 kB)
Clear Creek June 2006 Fact Sheet (PDF, 5 pages, 1 MB)
Proposed plan to amend the Records of Decision for OU3 and OU4 to add an on-site repository (PDF, 9 pages, 91 kB)
2007 Fact Sheet (VERY large PDF: 7.4 MB)
Records of Decision List (ROD List)
Amendments to Records of Decision (RODs)
Contacts
Ron Abel, State Project Manager
(303) 692-3381
ron.abel@state.co.us
Warren Smith
Community Involvement Manager
(303) 692-3373
warren.smith@state.co.us
Mailing Address
Colorado Department of Public Health and Environment
HMWMD-B2
4300 Cherry Creek Drive South B2
Denver, CO 80246
FAX: (303) 759-5355
Mike Holmes, Remedial Project Manager
(303) 312-6607
holmes.michael@epa.gov
Peggy Linn, Community Involvement Coordinator
(303) 312-6622
linn.peggy@epa.gov
Toll Free 800-227-8917
Mailing Address
U.S. Environmental Protection Agency
1595 Wynkoop Street
Denver, CO 80202-1129
FAX: (303) 312-6961
