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| 9/24/2009 10:28:00 AM | Email this article • Print this article | EPA seeks artistic approach to capping off mine waste
Ann E. Wibbenmeyer
Herald Staff Writer
Construction on the Denver City waste pile as an pilot study site will begin next week, according to Linda Kiefer, project manager for the U.S. Environmental Protection Agency.
The goal of the pilot study is to find artistic ways of capping acid-producing, mine waste piles left by the founding residents of Lake County.
At a public meeting on Sept. 17, Kiefer outlined the pilot study and the four methods being tested as possible remedies for the Greenback, RAM and Makato tailings piles in Stray Horse Gulch. These piles are visible both from the Mineral Belt Trail and East 5th Street, or CR 1.
Under the original record of decision for remediating the operable unit 6 of the California Gulch Superfund site, there were two piles that were capped as part of the remedy.
The rocks that were used to cover those piles changed the appearance of those historic tailings, which have since been referred to as "the wedding cakes" by Leadvillites ever since.
The other part of this decision was to send other acidic runoff into the Leadville Mine Drainage Tunnel, which was supposed to be plugged to ensure that all the water would be treated in the plant run by the Bureau of Reclamation.
The BOR has been unwilling to take responsibility for the OU6 water to complete the bulkhead to plug the tunnel.
This brought the EPA to announce earlier this year that the remedy chosen in 2003 was not working, and it informed the Lake County commissioners that capping otherwise undisturbed piles was the next option.
In 2003, this was an unpopular option, because the community wanted to preserve the history of those piles.
The community still wants to preserve that history. The pilot study is an attempt to compromise by capping the piles, but making them blend into the other historic mine piles.
On one section of the test pile, shotcrete will be used as the capping material. This is a light concrete that is sprayed onto the pile. It can be done with various colorations, according to Kiefer.
The section next to the concrete will be covered with inert rock and stabilized with timber cribbing, much like what is seen from the Mineral Belt Trail.
The inert rock, which is non-acid producing waste rock from other piles, would retain the historic look of the piles.
One community member at the meeting asked if this was stealing from Peter to pay Paul, meaning that the piles these rocks are being taken from would then be diminished.
Doug Jamison with the Colorado Department of Public Health and Environment assured that there would be plenty of inert rock for each pile.
The third section would be covered without the cribbing. This section may have to be graded so that the rock could be spread evenly over the pile.
The last section would leave the visible side of the waste pile with its natural face and only cap the back side. This way, only those hiking over the piles would notice the difference, said Kiefer.
The hope is that the construction of the test site will be done by the end of October, when the community will be invited on a field trip to see the outcome of the test pile.
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