Captain Jack Mill Superfund Site Will Get a Makeover
Karelle Scharff
Ward, CO At a well-attended meeting in Ward on the evening of July 2, the Colorado Department of Public Health and Environment, the EPA and Walsh Environmental presented their preferred alternative for the cleanup of the Captain Jack Mill Superfund site. Present were local Ward residents, representatives from the Left Hand Watershed Task Force, Left Hand Watershed Oversight Group (LWOG), Left Hand Water District, Boulder Historical Society, and from the Town of Ward.  The Captain Jack Superfund site encompasses several old mining and milling properties, including the Big Five, the White Raven, and the Captain Jack, all about a mile south of the town of Ward, west of Left Hand Canyon Road. The mines associated with the site were originally developed in the late 1800’s and included the Big Five tunnel which was dug into the mountain nearly a mile. Although the original mines and mills closed down in the first part of the 20th century, they were reopened in the 70s and the Captain Jack Mill processed ore from the early 80s to the mid-90s. Predictably 100 years of mining activity has left a heavy legacy of acid and metals pollution in the soil and water. In the early 80s when the Mill reopened, the EPA discovered fisheries and wetlands impacts in the Left Hand Creek watershed that they suspected were associated with the discharges of metal contaminated water from the surrounding abandoned mining and milling areas including the Captain Jack Mill site. In 2003 the Captain Jack Mill site was listed on the national priorities list of the EPA. Between 2004 and 2008 a remedial investigation and feasibility study (RI/FS) was conducted to identify the types, quantities and locations of contaminants and evaluated ways to address these problems.
The RI/FS presented at the meeting on Wednesday night identified eight “contaminants of concern” present in the soil, waste rock, tailings, surface water and mine impacted groundwater that pose a risk to human health and the environment at this site: antimony, arsenic, cadmium, copper, lead, manganese, thallium, and zinc. Three of these – arsenic, lead and thallium – present significant human health risks, while the other five present risks primarily to fish and other aquatic life. Both sets of risks were considered unacceptable. The plan proposed by the EPA intends “to prevent current and future exposure to contaminated soil, water and groundwater through a combination of treatment containment. The remedial response actions described in this proposed plan will permanently control and reduce the toxicity, mobility and volume of those source materials that pose a risk at the site.” The two agencies presented eight alternatives, the first being no action at all which it does not consider an alternative as it doesn’t meet any of the criteria the EPA sets up to determine the effectiveness of a solution. For the three alternatives evaluated to remediate surface contamination they chose the alternative known as “2B: ON SITE CONSOLIDATION AND CAPPED CELL FOR PRINCIPAL THREAT WASTE WITH THE REMAINDER CAP-IN-PLACE.” In this scenario the “principle threat waste” is excavated and placed in an on-site consolidation cell instead of being removed to an off-site disposal facility. The consolidation cell would be capped with 6 inches of topsoil on top of 12 inches of fill on top of a geo-synthetic clay liner. Before the clay liner is installed, a caustic material would be mixed into the top 6 inches of the waste material in order to neutralize it to minimize acidic leaching. EPA estimates the cost of this alternative to be around $1.3 million. They anticipate it could take 8 to 10 years to be fully operational. Of the four alternatives evaluated to deal with the acidic, metals-laden water leaking from the mine, alternative 3B: BIG FIVE ADIT BULKHEAD AND MINE POOL MITIGATION WITH PHASED SUCCESSIVE BIOCHEMICAL REACTOR TREATMENT AS REQUIRED, was chosen. This alternative installs a concrete plug – a bulkhead, approximately 10 feet thick, with pressure gauge and flow-through valve – approximately 470-675 feet from the portal of the tunnel. The idea is to create a pool of water behind the bulkhead that would both reduce oxygen available to the chemical processes that make the runoff acidic and contain the runoff itself. To further neutralize the acidic mine pools, injection wells will insert and circulate caustic chemicals to the water to raise its pH. Since alkaline water doesn’t readily hold metals in solution they will settle out into a sludge behind the bulkhead in the mine tunnel. During this neutralization process the water quality of Left Hand Creek will be monitored. If the cleanup objectives are not being met, the second phase of this alternative will be evaluated and implemented. This phase involves installing a series of vessels called biochemical reactors. The reactors use microorganisms to transform hazardous contaminants into nonhazardous substances. After the biochemical reactor treatment, water would flow through on-site wetlands for a “polishing treatment” before draining to Left Hand Creek. The EPA and CDPHE regard this alternative as the most flexible, and project its cost to be between $4 and $10 million, depending on whether the second phase is necessary. There were numerous questions from the assembly, some regarding historical buildings on the site, some regarding the effect of these operations on wildlife downstream, some about the operations and maintenance commitment of the EPA. But the most discussion was about damming the water in that tunnel. There was a great deal of concern expressed about possible seepage and the tendency of water to take the path of least resistance. The EPA representative reassured the audience that they would closely monitor the surrounding area for possible leaks. More information is available from Mr. Angus Campbell, CDPHE, Hazardous Materials Waste Management Division, (303) 692-3385,
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. For more information:
http://www.lwog.org
www.cdphe.state.co.us/hm/captjack/index.htm
http://www.epa.gov/region8/superfund/co/captainjack/
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Preparations were underway for the 8th annual Joe Colton Off Road Adventure Run. The race, which has obviously become a favorite for runners from altitude and from down below, was created by Lori Kinczel, in memory and honor of Joe Colton, a local youngster who died of the flu just over 8 years ago.
