by Austin Buckingham
Summitville Mine Superfund Site Project Manager, CDPHE/HMWMD

The 1,231-acre Summitville Mine Superfund site is located in the San Juan Mountains of southwestern Colorado, approximately 25 miles from South Fork. The remote site is situated at an elevation of 11,500 feet. Drainage from the site discharges to Wightman Fork, which 5.5 miles downstream joins the Alamosa River.

 Summitville Field Trip
Photo by Denis Hall
Field trip leader Austin Buckingham addresses participants with Summitville Mine site in the background.

Within the Alamosa watershed, three mineralized areas have an impact on water quality. The Stunner, Summitville and Jasper hydrothermal alteration areas have been historically explored for mineral extraction. The most exploited and profitable of these was the Summitville area, which has been mined since the 1870s. In accordance with the technology of the late 1800s and early 1900s, mining was conducted by boring horizontal tunnels or adits in the mountain. The ore-bearing rock was brought to the surface on rail cars, crushed and the precious gold, silver or copper was separated from the waste material. Mining at Summitville was marginal because the ore did not contain significant amounts valuable metals. The miners and their families were known to have lived in the town of Summitville year round, though there could be on average 30 feet of snow through the winter in the extremely remote region. Though conditions were harsh, there was a store and a school.
With the rising price of gold, large-scale surface disturbance generating even greater volumes of waste rock to extract microscopic quantities of gold became economically practical at Summitville. In the early 1980s, Galactic applied for and received a permit to operate a cyanide heap leaching operation. Following the 1984 issued permit, the mining company began without delay to construct the infrastructure for open pit mining and gold extraction. Notwithstanding the fact that the permit allowed for inadequate reclamation bonding in the event the company defaulted on mine closure and for insufficient mine oversight, the operation was doomed to failure almost immediately due to several critical design, construction and environmental factors. They were: 1) an enormous snowfall and spring melt-off resulting in an overwhelming volume of water, much of it contaminated from the now exposed mineralized surface, 2) the lack of water treatment or water storage facilities to manage contaminated water, 3) a poorly designed and constructed heap leach pad, 4) a clayey ore with microscopic quantities of gold, and 5) a plunging gold price. Within a few short years, Galactic realized they had an unprofitable operation and were trapped in an impending environmental disaster; thus they packed up and left town. The Summitville disaster resulted in uncontrolled acid mine drainage and contaminant releases to the Alamosa River in the late 1980’s and by 1990 large fish kills were documented in the river and in Terrace Reservoir 20 miles downstream of the site and beyond. The mine site was out of control. Galactic spent $180,000,000 to develop the mine and made $200,000,000 in gold profits, therefore only netting $20,000,000.

 Overview of Site
Photo by Denis Hall
Overview of the Summitville Mine Site from atop the “high wall”.

Contaminants of concern are aluminum, ammonia, copper, iron, manganese, zinc and low pH discharges. The primary contaminant pathway is surface water; therefore aquatic life in the Alamosa River has been negatively impacted. Human health impacts are not present. Downstream of Terrace Reservoir, the Alamosa River is entirely appropriated for agricultural purposes in the San Luis Valley. For more than six generations of landowners, the valley’s main livelihood has been farming and cattle ranching. Without the water the Alamosa River provides, this high altitude dry valley could not thrive.
As of December 1992, the Environmental Protection Agency and the State of Colorado have been the custodian of the site, first under emergency response then in 1994, as a Superfund site. From 1992 to the present, superfund remedial actions include:

  • Placement of bulkheads to control drainage from the lowermost adits
  • Construction of water treatment systems and contaminated water storage impoundment
  • Cap and revegetate the heap leach pad
  • Consolidation of waste materials from the Cropsy Waste Pile, the Beaver Mud Dump, and mine pit closure
  • Recontour, cap and revegetate exposed areas
  • Construction a surface water management system to direct water either to the contaminated water storage impoundment or off-site depending on chemistry
  • Construction of point source contaminant collection system

Throughout the final remedial investigation and feasibility study, the Alamosa River and Terrace Reservoir were modeled and studied intensively. The studies include aquatic life (a count of individuals and specie diversity, and metals content), habitat and metals concentration in the water column and the sediment. The final remedy aimed to achieve the major goal of returning aquatic life to the impacted surface water environment.
With the completion of the majority of the remedial actions, water quality has improved in the Alamosa River. From 1994 to 2000 in Terrace Reservoir, aluminum, copper, iron and zinc has been reduced by 80% to 99%. Based on the improved water quality, the State and Federal agencies decided in 2000 to conduct both a short-term and long-term aquatic life test in the reservoir formerly devoid of aquatic life. In 2001, 7,000 6-inch rainbow trout were placed in the reservoir for long-term monitoring (year 2001). This study continued for two years. The fish were sampled for metals content before placement in the reservoir for a baseline analysis, then twice the first year and once the second year. The fish were growing in both weight and length. Unfortunately in the year 2003, the reservoir was drained for repairs to the outlet works; therefore the test was terminated. Regardless of the premature end of the long-term survival test, the agencies believe that substantial progress has been made in restoring the aquatic life of the Alamosa River.
As configured, the current water treatment plant cannot meet stream standards. The final remedy includes the construction of new water treatment plants that will more efficiently and effectively remove metals from the treated effluent. Future work includes construction of a new water treatment plant, and if necessary, enlarging the contaminated water storage impoundment. The remedial goal is to return the river to its pre-mining condition by stabilizing the water management and storage so that untreated or contaminated releases from the Summitville Mine Superfund Site are eliminated. To date, approximately $180,000,000 has been spent on remediation and water treatment. The total cost (assuming 100-year life with the attendant operation and maintenance) are estimated in excess of $250,000,000. Following construction of the major remedial elements, the State of Colorado will continue as the custodian of the Summitville Mine Superfund Site in perpetuity.

Colorado Riparian Association