Dangerous levels of dioxins and other deadly contaminants from the defunct Smurfit-Stone mill site did not wash into the Clark Fork River during this spring’s high water.
That was the finding of emergency water sampling conducted by the U.S. Environmental Protection Agency after citizens of Frenchtown and Missoula expressed concerns during the flood.
Members of the Smurfit-Stone Community Advisory group received the report Thursday night.
“What I can tell you, looking at these numbers, they’re at or below what we consider a concern,” EPA remedial project manager Sara Sparks told the 22 people gathered at the Frenchtown Fire Hall.
In May, as the Clark Fork River rose above flood stage, groundwater was forced up into a number of old holding ponds that had contained liquid byproducts of the pulp-making process conducted at the former linerboard plant.
While the Frenchtown mill was operating, some of that liquid used to percolate into the ground where many of the contaminants were filtered out before the liquid bubbled up into the nearby river.
But when the river flooded this spring, the groundwater reversed course, carrying some of those solids with it, making colored water appear to boil up from the bottom of the ponds.
Then, as the Clark Fork River dropped again, dark “tea-colored” water was observed outside the berm that separates the ponds from the river.
Residents and local officials worried that contaminants from the pond were flowing back to the river and demanded action.
Sparks said her team responded between May 18 and May 20, sampling water in seven locations around the site: some in the river, some in the ponds and at one well on the site.
After sampling, they also added 3,500 cubic yards to the bottom of one of the ponds so groundwater wouldn’t bubble up again with the next flood.
Sparks had results for heavy metals, but she focused on the results for dioxins. Dioxins, namely chlorine dioxin used to bleach paper, are highly toxic even at low levels and remain in the environment for decades.
So they were the biggest concern.
But except for the sample from the well, all samples had safe dioxin levels, with toxicity falling below the human-health standard.
Keith Large, Montana Department of Environmental Quality Superfund Project manager, said the well is known for having higher levels of contaminants. Fortunately, dioxins bind tightly to soil so they don’t move with groundwater.
“Thank God we are not seeing elevated levels of dioxins in the river,” Sparks said.
The May sample results showed that toxic metals are more of a problem. Aluminum, copper and lead were all found at levels exceeding EPA water quality standards. But the levels are high at a point in the river above the Smurfit site so the mill isn’t the only source of contamination, Sparks said.
The Clark Fork River has many old mining sites along its course and that of its tributaries, so some of them could be adding pollution to the river before it reaches the mill site.
“We have a problem with those metals, but it’s not an emergency,” Sparks said.
The EPA will publish a summary of all the sample data next Wednesday.
With the emergency averted, Sparks’ team will continue the normal sampling that goes along with the long process of remedial investigation. On June 11, they’ll start their seventh round of groundwater sampling, and at the end of June they’ll assess the berms between the ponds and the river for stability and longevity.
During the summer, they’ll collect additional water samples from the site and the Clark Fork River. In addition, they’re considering working with Montana Fish, Wildlife and Parks to sample fish tissue.
“We’re completing the human-health and ecological risk assessment that is needed before we can complete the remedial investigation. Once we do that, we move into the feasibility study where we’ll look at do we need to clean it up and how do we clean it up. It’s a long, painful process,” Sparks said.