Eagle Mine site summary

 
Location
  • The mine is located approximately eight miles southwest of Vail and one hundred miles west of Denver. 
  • The 235-acre site includes the Eagle Mine workings, the town of Gilman, eight former mine tailings piles, Rock Creek Canyon below Highway 24 and at least 14 waste rock piles between Gilman and Minturn in Eagle County, Colorado. 
  • The consolidated tailings pile is 1,500 feet southeast of the Minturn Middle School and numerous residences.
  • The Eagle River flows northwesterly through the site.
History
  • Mining first began in the Gilman area in the late 1870s for gold, silver, lead and zinc. 
  • Four roasting and magnetic separation plants used to process the ore until 1919. 
  • An underground mill constructed to extract lead and zinc metals operated from 1919 to 1979. Copper-silver production continued until 1984 when the mine workings were allowed to flood.
  • Colorado filed notice and claim against the former mine owners for natural resource damages under the Superfund law in 1985. 
  • The site was placed on the list of Superfund sites in June 1986.
Environmental Concerns
Contamination includes:
  • Lead, zinc, cadmium, arsenic and manganese associated with the mining wastes. 
  • The major pathways of concern are surface water contamination to the Eagle River, groundwater contamination and ingestion/inhalation of mining wastes.
Site Remediation
  • We entered an agreement regarding cleanup activities with  the previous mine owner/operator (Gulf + Western Industries, now Viacom International, Inc.) in 1988. 
  • The cleanup plan included flooding the mine workings by bulkheading mine adits, relocating all processed mine wastes and contaminated soils to one main onsite tailings pile, capping this pile with a multi-layer clean soil cap and revegetating all disturbed area with native plant species.
  • Cleanup began in 1988 with the relocation of mine wastes and capping of the main tailings pile. 
  • Flooding of the mine workings resulted in unacceptable seepage into the Eagle River beginning in late 1989. 
  • A water treatment plant was constructed in 1990 to collect mine seepage, groundwater at the main tailings pile and precipitation accumulation on tailings removal and relocation areas. 
  • The water treatment plant treats approximately 140 million gallons of water annually, and removes approximately 175 pounds per day of zinc. 
  • Water quality in the Eagle River has shown improvements beginning in 1991.
  • Ongoing activities include a program to sample water quality, aquatic insects and fish populations in the Eagle River to assess the effects of cleanup and evaluate the possibility of establishing biological-based cleanup standards for the site. 
  • An additional 700 cubic yards of zinc concentrates have been moved to the consolidated tailings pile. 
  • 100-200 gallons per minute of clean groundwater are being intercepted and diverted from the Eagle Mine.
  • Reviews have concluded that public health risks have been removed and that significant progress has been made in restoring the Eagle River.