Officials propose capping East Helena slag pile in final cleanup plan

By Tom Kuglin, Excerpt from the Helena Independent Record 

The reshaped Prickly Pear Creek flows through former Asarco property beneath the East Helena slag pile. Officials with the Montana Environmental Trust Group and EPA propose capping the slag pile in place as part of their final cleanup plan. Thom Bridge, thom.bridge@helenair.com

The environmental trust group charged with cleanup of the former East Helena smelter site proposed building a cap over the East Helena slag pile to prevent storm water from spreading contamination as its final major step in remediating the site at an open house in East Helena Wednesday.

The Montana Environmental Trust Group and Environmental Protection Agency presented a draft of its final cleanup plan, called a corrective measures study. The document, which is open for public comment, incorporates remediation and protective actions completed to date with remaining work the trust proposes.

The trust controls both the smelter site and Asarco-owned lands in the area. Contamination includes arsenic and selenium in soils at the site that have caused groundwater plumes and levels above safe drinking water standards.

In the years since the settlement and ahead of the corrective measures study, contractors have analyzed contamination and performed “interim measures” addressing pollution. Interim measures have included capping much of the site to isolate contaminated soil, removing some soil, dropping groundwater levels to stop or slow the leeching of contaminates into the water, and rechanneling Prickly Pear Creek.

On Wednesday, officials told about 40 people in East Helena that those interim measures have begun reducing concentrations and the size of plumes by largely cutting off their sources.

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