Officials propose capping East Helena slag pile in final cleanup plan

Source: Helena Independent Record
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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.

In 1998, a century of contamination at the East Helena lead smelter site and other facilities resulted in a multimillion dollar settlement between Asarco and the EPA for violations of the Resource Conservation and Recovery Act (RCRA) and the Clean Water Act. The smelter closed in 2001, and after later declaring bankruptcy, Asarco placed about $96 million in a trust managed by the Montana Environmental Trust Group. The state of Montana is a beneficiary in the trust via the Montana Department of Environmental Quality and the Montana Department of Justice, along with the EPA.

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.

Bob Anderson, a contractor at the site, told the open house that contamination levels at the site have dropped “significantly,” saying arsenic levels are down 50 percent and there’s been up to an 80 percent drop for selenium. Offsite where plumes have traveled to the northeast, concentrations have dropped less, but data has shown plumes receding.

“Everything we’re doing is designed to keep people from being exposed,” he said.

Selenium tends to move much faster in groundwater and the modeling suggests a significant recession towards the plant in the next 20 years. Arsenic moves much slower, Anderson said, and shrinking the plume back to the smelter site is a decades-long proposition.

Other contractors detailed work to restore wetlands and establish vegetation along the creek and across the site, indicating some early success.

Lauri Gorton, East Helena director of environmental programs for the trust, detailed the administrative side of the cleanup, with the trust needing EPA approval on its final plan. With a finite amount of funding – about $50 million remaining – measures are designed to minimize the need for future work.

“These things work on their own and are sustainable over time,” she said.

Cost-benefit analysis of the cleanup made it clear early on that removal of all soil and the slag pile is too expensive, she said.

“Why not dig up the soil and slag? The answer is there is too much of it, it wasn’t feasible,” Gorton said.

Recognizing that the slag pile is a “significant visual landmark,” engineers would look to shape and cap it to blend in as much as possible, she said. There is also the possibility that the slag could be purchased and processed for other purposes, and capping it would keep that option viable, she added.

Officials also looked at pumping and treating the water, which was deemed cost prohibitive as well. Anderson said that pumping could reduce concentrations, but not the extent of the plumes, as soil around the plumes is now also contaminated and would re-pollute the water.

Attendees grilled officials on the remaining budget, cleanup plans offsite on other Asarco lands and controlling storm water from the site.

Remaining funding will include extensive monitoring and potential remediation at other Asarco properties, officials said.

Written comments may be sent to: Betsy Burns; EPA Region 8 Montana Office; 10 W. 15th St.; Suite 3200; Helena, MT 59626. They may be emailed to: burns.betsy@epa.gov. The public comment period for the CMS report ends on May 29 at 5 p.m.

To view the corrective measures study, go to http://www.mtenvironmentaltrust.org/.