Captain Jack Superfund Site

This site is one of the "Superfund" hazardous waste sites in Colorado. A site qualifies for the National Priorities List (NPL or Superfund list) when the U.S. Environmental Protection Agency (EPA) determines there is a release or threatened release of hazardous substances that may endanger public health, welfare or the environment. In Colorado, the lead agency for Superfund remediation may be either the EPA or the Colorado Department of Public Health and Environment (the state health department).

What's New

The revised Community Involvement Plan is now available.

Site Summary	Planned Activity
Environmental Concerns	Related Web Sites
Monitoring Data Application	Superfund Site List
Record of Decision

Record of Decision - Identifies the selected remedy for contaminated soils and surface water discharges associated with the Captain Jack Mill Superfund Site.

Copies of the feasibility study and Record of Decision are also available at the information repositories in both Ward and Boulder Public Libraries, as well as the Colorado Department of Public Health and Environment, Hazardous Materials and Waste Management Division records center.

(888) 569-1831 toll-free (extension is the last four digits of their direct number)

Site Summary

Location

The Captain Jack Superfund site is located at the headwaters of the Lefthand Creek Watershed in a narrow valley about 1.5 miles south of Ward in Boulder County, Colorado.

History

Mining for gold and silver began in this region in 1861 and continued intermittently until 1992. Camp Frances, near Ward, was started in the early 1890s. It was here that the Big Five Mining Group managed several mines, including the Adit, Ni-Wot, Columbia and Dew Drop. The combined ores came down to the Camp by way of the adit tunnel. Processing was carried out in the Dew Drop Mill or the larger Big Five Mill - located on the side of the gulch below the Camp. The Colorado and Northwestern Railroad was built through the Big Five/Camp Frances area to the town of Ward to service the mining area.

The histories of the Big Five Mine, located about 500 feet upstream from the mill, and the Captain Jack Mine (also known as the Black Jack Mine) are uncertain. The Black Jack Mine operated intermittently as an underground mine following its patent approval in 1917. The Big Five Mine operated without a permit, so there is no way to track its official history through conventional paper trails. It is unknown how long it originally operated before it was shut down.

The Big Five Mine consists of an adit (tunnel), a large waste rock pile and a settling pond. The Mill Works area includes several lagoons previously used for settling tailings from the mill. The lower portal consists of the Black Jack adit and the contents of a shed. Other mine wastes include waste material in Lefthand Creek and waste rock from the mine tunnels.

The EPA added the Captain Jack site to the National Priorities List (NPL) on September 29, 2003.

Environmental Concerns

Chemicals

Samples indicate the presence of elevated concentrations of lead, arsenic, thallium, zinc, manganese, copper, magnesium, cadmium, aluminum, calcium and iron. Site contaminants of highest concern are lead, arsenic, and thallium.

Exposure

Lefthand Creek is one of the sources used by Lefthand Water District to supply drinking water to approximately 15,000 water users. Elevated levels of metals and other contaminants have been found in surface water and sediment samples from Lefthand Creek and its tributaries and from wetlands fronting along the creek. Groundwater samples from two nearby wells show elevated levels of metals. Uncovered tailings, ore concentrates and surface soil contaminants could pose a threat of dust emissions, especially to the nearby residences. In addition to human exposures, the elevated metal concentrations in sediments and water entering Lefthand Creek affect aquatic life.

Overview of Selected Remedy

The selected remedy for cleaning up the Captain Jack Mill Superfund Site has two components, as it controls both surface and subsurface contamination sources.

To control subsurface contamination, the remedy (Alternative 3B in the Remedial Investigation / Feasibility Study) consists of an installed bulkhead, mine pool mitigation, and phased successive biochemical reactor treatment. The concrete bulkhead will plug the draining mine adit, impounding the mine water. The mine pool environment will have reduced oxygen levels, which, coupled with an injected caustic chemical, will increase the pH of the water to a neutral condition (Phase I). If necessary, after approximately two years of neutralization, the Colorado Department of Public Health and Environment may install a series of biochemical reactors outside of the mine (Phase II). The reactors use microorganisms to transform hazardous contaminants into non-hazardous substances. Following bioreactor treatment, the water would flow through wetlands for additional "polishing" treatment before entering Lefthand Creek. Because of uncertainties over the mine workings, there will be extensive groundwater monitoring once the bulkhead is installed.

Under the selected surface remedy (Alternative 2C), all waste will be excavated and placed in several onsite consolidation cells. The selected remedy calls for excavation of all site material containing contaminants of concern in concentrations above the remedial action levels.

To contain the waste, each consolidation cell will have a cap. The caps will likely consist of a liner impervious to water, coarse material to prevent rainwater from seeping down and contacting the waste, and topsoil to support vegetation. Before the liner is placed on the waste, alkaline material would be mixed into the top six inches of the waste material to minimize acidic leaching. Officials will fully evaluate potential locations for the consolidation cells, as well as locations from which to borrow dirt for the cap, during the design phase.

Hazardous Materials and Waste Management Division Captain Jack Mill (Left Hand Canyon, Boulder County)