By Jonathon Ambarian, from KTVH.com
EAST HELENA – Four years ago, the site of the former ASARCO smelter in East Helena was crowded with buildings. Today, almost all of them are gone.
It’s the most obvious sign of the long-term project to clean up the Superfund site, led by the U.S. Environmental Protection Agency and the Montana Environmental Trust Group, which took over the site as part of ASARCO’s bankruptcy settlement.
For more than 100 years, ASARCO conducted lead and zinc smelting operations in East Helena. Soils around the smelter were contaminated with lead and other heavy metals, while chemicals like arsenic and selenium leached into the groundwater, spreading beneath East Helena in large plumes.
The EPA laid out three key steps to address the contamination: placing a cap over the site, redirecting Prickly Pear Creek and removing limited amounts of contaminated soil. Work on the cap and the new channel for the creek were completed last year.
Betsy Burns, the EPA’s remedial project manager for the ASARCO site, said the 60-acre cap over the smelter area is one of the largest in the U.S. It’s about three feet of clay, designed to protect people and wildlife from the materials underneath and to keep rain and snow from carrying those substances into the groundwater.
“It allows moisture to infiltrate into that, and then it’s uptaken by the grasses that are planted on the top of the cap system,” Burns said.
The cap system also includes a concrete drain around the outside, to carry extra runoff away from the contaminated area.
Rechanneling Prickly Pear Creek was another major effort. Burns said the creek had been rerouted multiple times over the years as the smelter complex expanded. A dam had also been built, creating two small lakes that bordered contaminated soils.
Crews removed the dam and lowered the creek by several feet in order to bring down the groundwater level and keep it from reaching contaminated area. They also created a more natural, meandering channel for the creek, including a floodplain along its banks.
The water is also farther from the massive East Helena slag pile. Burns said the creek had begun eroding parts of the pile.
While workers did remove some of the contaminated soils from the smelter site, Burns said it would have been far too impractical to remove all of them. Altogether, she said the volume of affected soil would have been equivalent to the size of the slag pile.
“There are ways to manage materials without moving them,” said Burns.
Burns said the EPA is now considering covering the top portion of the slag pile with a similar cap to the one placed over the smelter area. She said the material in the lower part is more solidified, so it poses less of a risk.
Most of the actual construction work at the smelter site has been completed. A public hearing on the final remediation projects could happen as early as this fall or winter. But the EPA will remain in the area for years to come, monitoring contaminants.
Burns said the EPA has already seen results from the work they’ve done at ASARCO. For years, they’ve been measuring arsenic and selenium concentrations in wells around the smelter area. Since 2012, Burns said those concentrations have been trending downward.
This year, crews have focused on restoring the area around the smelter site. They replanted much of the property with native vegetation.
“We’ve gotten some really good grassy vegetation within the floodplain, as well as different shrubs and bushes that have been planted, and you’re starting to see really good willow growth on the banks,” Burns said.
Capping the site has also made it more attractive to wildlife, like birds, deer and foxes. Removing the dam has opened Prickly Pear Creek up for fish. Burns said crews will start conducting surveys on fish populations in the coming years.
East Helena Mayor James Schell and members of the city council toured the smelter site earlier this year. Schell said he’s particularly excited about possible recreational opportunities there.
“To turn that into something that’s good, and to turn that realignment area into public access, with walking trails and fishing access, is a great thing for the area,” he said.
Schell said the cleanup has been a long process, and residents are happy to see any visible progress at the site.
“We really look forward to moving forward in the next five years, to finish off with the site activities, to close this chapter in the East Helena area,” he said.
Burns said the results of the cleanup so far have exceeded her expectations. Soon, she said they will be ready to show off the progress they’ve made at the smelter site to the East Helena community.
“Be looking for next spring, we’d like to have some public events out here,” Burns said.