Swan River set to be PCB free

The cleanup of two contaminated sites around PacifiCorp’s power plant on the Swan River that began the first week of February is planned to continue today and be completed by the end of week.

That’s the plan at least. With winter weather, equipment issues and access problems, PacifiCorp engineers and the cleanup crew at Water & Environmental Technologies encountered a longer process than was originally estimated.

Polychlorinated biphenyl (PCBs) were found on the southwest bank of the river both upstream and downstream of the plant just outside of downtown Bigfork. The contamination is thought to be the result of spills that happened over time in PacifiCorp’s transformer yard.

“PCBs were found from zero to six inches in the soil,” said Chris Cote, a project officer with Montana’s Department of Environmental Quality who is overseeing the PacifiCorp cleanup. “PacifiCorp is aware of that. They are hoping to remove the last of the contamination this winter.”

Equipment showed up around the first week of February, a walking excavator and a vacuum truck with a vacuum hose. Clean up started with the site located downstream of the power plant, just below Sliter Park. The excavator dug out the contaminated soil and the vacuum truck sucked it up without a hitch.

When it came time to do the same directly upstream of the plant, the vacuum truck couldn’t get the job done.

“It was too silty,” PacifiCorp engineer Jeff Tucker said. “It wouldn’t move with the super-sucker.”

There is a lot more clay in the soil on that side of the plant. It was too heavy to vacuum up, so PacifiCorp had to find a plan B.

Plan A involved the walking excavator crawling across the river digging up contaminated sediment with the vacuum hose crawling around the plant to suck-up the sediment. So, the original plan involved minimal needs for heavy equipment access to the site.

Plan B is a bit more involved.

It calls for crane removal of the remainder of the contaminated sediment. But, the only place to safely put the crane is above the waterway that flows down the hill above the power plant. The only bridge over that flume isn’t strong enough to hold a crane’s weight.

To get the crane over the bridge, the cleanup crew has to bring in a bridge-builder. Which is essentially a set of I-beams that stretch from one side of the waterway to the other. The crane will use that to cross the bridge and proceed with soil removal.

At this point both banks have been filled back in. The cleanup crew will have to re-dig up sediment from the contaminated site, remove it and replace it. As long as weather cooperates and the river level doesn’t rise, this process will start today.

PCBs were used to cool electrical transformers until its use was banned in 1979. The Environmental Protection Agency looked at PacifiCorp’s transformer yard for PCB contamination in 2000. The EPA found significant contamination. According to EPA documents PacifiCorp completed voluntary cleanup of the yard in 2003 and removed contaminated soil from a 800-square-foot area.

Tucker said PacifiCorp’s best guess of how contamination happened is that over time leaks and spills from the power plants transformer cause PCBs to leech into the soil surrounding the area.

In 2009 the EPA and DEQ were concerned PCB contamination might have reached the Swan River from the yard. At that time the Montana DEQ requested that samples be taken from the shore of the river near the plant. PCBs were found.

PacifiCorp acted quick enough to get a clean up plan application into the DEQ last year, but it wasn’t approved.

PacifiCorp modified their plan to comply with DEQ’s requests and rather than take the time to reapply for application approval, they proceeded with their cleanup this winter.

“We wanted to make sure we got it out as quickly as we could,” Tucker said. “We’ve taken out three yards of soil so far.”

The contaminated sites are below the high-water mark. That makes the best time to access them during the winter when the river level is low.

Because the site is listed on the state’s Comprehensive Environmental Cleanup and Responsibility Act list, the application is based on volunteer cleanup. Which means, the DEQ doesn’t pay for or staff clean up. Technically, the DEQ doesn’t have to approve the volunteer cleanup application before PacifiCorp can begin. But the DEQ does have to approve the application and that the cleanup was successful, before PacifiCorp is off the hook.

PacifiCorp will re-submit an application to the DEQ in April after clean up of the site is completed, and soil samples are taken and analyzed to prove the PCBs were removed.

While the DEQ and the EPA have both seen the revised plan, it’s not officially approved yet. Cote said that once the plan is submitted to the DEQ, they have 30 days to respond to whether or not they approve.