This piece was produced by KBMF News Team volunteer Ted McDermott.
Aimee Reynolds knows a lot about dioxins.
A risk assessor with the Montana Department of Environmental Quality and the agency’s contaminated site bureau chief, Reynolds has spent a significant part of her career trying to find ways to remove these highly toxic, cancer-causing compounds from contaminated sites around the state, from Frenchtown to Columbia Falls.
Reynolds was giving a presentation on dioxins in Butte, at Quarry Brewing, because there’s a 40-acre site in the Boulevard neighborhood, south of Uptown, where dioxins contaminate the soil—and where DEQ, the EPA, and others have spent some 23 years trying to clean up dioxin and a variety of other chemicals. Those chemicals were deposited in the soil between 1946 and 1984. During that time, the Montana Pole and Treating Plant operated on the site, soaking wood products in a variety of noxious chemicals—including pentachlorophenol (or PCP), petroleum, and dioxins.
After the site closed, the EPA led an emergency clean-up of the site in 1985. Two years later, the site was added to the Superfund National Priority List. And in 1993, a water treatment plant was built on site to treat the toxic chemicals before they enter Silver Bow Creek. As for the chemicals in the soil itself, the agencies overseeing the clean-up tried to deal with them beginning in 1995. That’s when a “Land Treatment Unit” was built on the site.
The idea was, the contaminated soil would simply be moved to a certain lined area, where exposure to sunlight and other natural elements, plus some tilling and water, would lead to the natural decomposition of the PCP, petroleum, and dioxins. Over the next seven years, more than 200,000 cubic yards of contaminated soil were rotated through the Land Treatment Unit. That process ended in 2002.
But it wasn’t until 2011—nine years later—that DEQ released some surprising information: soon after it began the Land Treatment Unit process, it became evident that the dioxins were resisting treatment and weren’t breaking down. DEQ continued the process, however, because it was effectively removing PCP, which was considered the toxin of greatest concern due to both its toxicity and its mobility, or tendency to spread.
And the cleanup of 95 percent of the PCP did have another benefit: it helped keep the dioxin from moving in the soil.
According to Aimee Reynolds, the DEQ risk assessor, dioxin isn’t mobile, unless it can pair with a liquid, like PCP. While dioxin is stable in the soil at the Montana Pole Site, it is still there, in the soil. The only way to get rid of dioxin would be to put it on trucks and train cars and ship it away—or to incinerate the soil on site. While DEQ has considered these and other, more experimental treatments, the agency has decided that these alternatives are too costly or too risky. So now, instead, the agency plans to simply bury the waste on site and put a cap over it that will reduce exposure to humans and the environment. That cap will reduce exposure—but it won’t eliminate it.
To determine whether capping and leaving the dioxin will be safe, DEQ relies on a process called risk assessment, which Reynolds described for a small audience at Quarry Brewing. The risk assessment Reynolds and the DEQ have done shows that exposure rates will be very low. On parts of the site slated for industrial use, the dioxin will be cleaned up to .00003 milligrams per kilogram.
While DEQ insists these exposure levels are safe, Montana Tech professor and Citizens Technical Environmental Committee board member John Ray says he remains concerned about the plan. But according to DEQ’s project manager for the site, David Bowers, the plan as it stands now is to cap the dioxin-contaminated soil on a 9-acre parcel of the site and leave it there in perpetuity—a solution he argues will be safe.
According to Bowers, that 9-acre parcel of capped dioxin-contaminated soil. could then be used for limited industrial use—such as a parking lot or storage—to accompany an approximately 15- acre parcel that is slated to be remediated for unlimited industrial and commercial use. Those 24 acres of the 40 acre site all lie south of Interstate 90.
DEQ is in the final stages of planning and hopes to complete work on that southern parcel soon. Once that southern parcel is complete, Bowers says DEQ will turn its attention to other issues on the site, such as trying to speed up the treatment of the groundwater and finding a way to clean up a portion of the site that is currently underneath a stretch of I-90.
All of this work needs to be done, however, with what remains of the settlement that was agreed to in 1996, shortly after a Record of Decision was agreed to for cleaning up the site. Of the $41 million dollars received in the settlement, approximately $29 million remains. While that sounds like a lot of money, the need to continually treat the groundwater for the foreseeable future means that $29 million will have to last for what has been projected for a period of 30 years—or more.