Tie plant's five-year review reveals unanswered questions

The fourth five-year review of the remedial actions performed under the Superfund program for the Burlington Northern Somers Tie Plant by the Montana Department of Environmental Quality and the U.S. Environmental Protection Agency has revealed some unanswered questions regarding the extent of the site’s contaminated groundwater.

The executive summary of the five-year review reads “the groundwater remedy is not protective of human health and the environment because new information generated since the last five-year review shows the plume is unstable, the vapor intrusion and drinking water pathways have not been fully evaluated, and the correct institutional controls do not cover all areas where contamination is above the Record of Decision cleanup standards for groundwater.”

“I want to emphasize that we haven’t found new or immediate risks,” EPA project manager Diana Hammer said. “We just have questions about the protectiveness of the remedy.”

The Somers plant operated from 1901 until 1986, where railroad ties and other lumber products were treated for protection from insects and weathering.

The site consists of roughly 80 acres next to Flathead Lake in Somers and the site is contaminated by nitrogen bearing heterocyclic bases, zinc, phenols, creosote, tar acids and bases, petroleum, and several metals such as arsenic, lead, and selenium.

The 1989 Record of Decision called for treating contaminated soil on-site in a land treatment unit and constructing and operating a groundwater treatment plant. The remedial action started in 1991 with reviews every five years.

The most recent five-year review’s sampling results have raised questions about how far from the plant the contamination could spread.

“A lot of it right now is we’re doing some confirmatory work to see where things are and where they are not,” DEQ Project Officer Lisa DeWitt said. “I know it does sound really bad, but as things are right now there’s not a big exposure risk. The biggest thing is groundwater, but nobody (in the Somers area) uses groundwater because they are on city water.”

This essentially means the contamination’s extent remains undetermined so the DEQ and EPA have concluded that the remedy’s groundwater section is not protective of public health and the environment.

The groundwater treatment plant was operated from 1994-2007. In 2002 the treatment was completed and the land treatment unit was closed, but under state law a controlled groundwater use area was created in 2003 and monitoring continues.

The previous five-year review from Sept. 2006 focused extensively on the groundwater component of the remedy because the soil component was certified as complete.

This year’s five-year review also found that the site remedy’s soils component is performing as intended and remains protective of the environment and public health.

The most recent five-year review maintains that the soil remedy protects human health and the environment because the contaminated soil was treated, placed in a land treatment unit at the site, covered with clean-fill soil, and surrounded by a fence to prevent access. However, enforceable institutional controls for the area need to be implemented for long-term protection.

The groundwater treatment systems were shut down in 2008 at Burlington Northern’s request because they weren’t extracting a lot of material from the groundwater. The EPA and DEQ agreed to this request, but continued monitoring to see what effect it would have.

Now the EPA and DEQ are working with Burlington Northern to start installing monitoring wells around the site to keep track of changes in the groundwater. A public meeting regarding the groundwater status and the results from those wells is anticipated for later this summer.

For a summary of the details and proposed actions, see the related article.

To read the entire five-year review, go to http://deq.mt.gov/fedsuperfund/BNS.mcpx or request a CD copy by contacting Hammer at hammer.diana@epa.gov or by calling 457-5040. Or by contacting Lisa DeWitt, DEQ Project Officer, at lidewitt@mt.gov or call 841-5037.