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| Tin Mine Report - October 7, 2004, Progress Review Trip | ||||||||||||
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Fourteen TREPA members were treated to a tour of the former East Kempt Mine, owned by Rio Algom, where tin was the focus of attention from 1985 until it closed in 1992. Currently, a staff of three monitors ground water and surface runoff and maintains treatment of surface water. In general, the surface water prior to discharge is low in pH, and therefore high in heavy metals. Most of the surface water is collected in a central ditch, from which it is pumped to a primary treatment plant for treatment with lime slurry. This tends to raise the pH to between 9 and 10, and leads to the precipitation of most of the heavy metals. | ||||||||||||
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 | Central collection ditch, with tailings ponds in the background. | |||||||||||
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 | Close-up of the water on the collection ditch Following treatment, the water eventually reaches a series of tailings ponds. Initially, one pond was built, but Rio Algom was obliged to construct two dams to divide the pond into three smaller ones. This allows more thorough treatment of the runoff. | |||||||||||
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 | A secondary treatment plant treats all water as it passes from the second to the final tailings pond. | |||||||||||
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Finally, a backup plant (to the right) is in place on the lowest tailings pond to treat surface water in case the other two plants encounter problems. The tall white structures are the lime silos for the secondary and backup plants. In the foreground is the outlet canal from the site. | ||||||||||||
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 | Some of the TREPA members looking at
the outlet from the site. By the time water reaches this point the pH is at accepable levels for discharge. | |||||||||||
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 | The lower reaches of the site are enclosed by a clay-core dam, to contain runoff and seepage. | |||||||||||
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Our hosts told us that this monitoring and treatment program was expected to be inplace for fifty to a hundred more years. So far, progress in treating the runoff has been better than expected. There is hope that the pollution leachate from the site will cease to be a problem more rapidly than this. However, it is too early to conclude this, and continued monitoring will be essential. Ground water is monitored through sampling at numerous artesian wells on and near the site. No serious problems have developed, but the possibility remains. We were very happy with our visit. Paul and Gary, of the on-site team, gave us a friendly and frank tour of the premises, and we thank them! John Sollows Report 10/18/04 | ||||||||||||