HELENA – Montana’s history of mining from a century ago has left the state with a toxic legacy that officials continue to deal with.
The Montana Department of Environmental Quality has an inventory of 3,000 abandoned mines.
That includes an old mine that’s spilling 165 gallons of polluted water a minute into a creek just outside the town of Belt.
“So for half the year the community has a red creek running right through the middle of the community,” said DEQ Reclamation Specialist Thomas Henderson.
Water from the closed entrance of the old Anaconda coal mine travels across several fields before it tumbles down a rocky ledge and into Belt Creek. The bright orange/red water contains high levels of iron. It’s mixed with white water that contains dissolved aluminum.
Across from the polluted water is a small beach that makes up Belt’s community swimming hole.
“It’s one of the few accesses to lower Belt Creek that the public can go recreate in Belt Creek,” said Henderson. “And unfortunately it coincides with the location of the acidic water coming in.”
This week Henderson oversaw a water pumping operation in the bluffs above Belt. Nearly 300 feet below Tiber Butte Road is a small lake of groundwater nearly a half-mile long and 15 feet deep that is pooled at the head of the old mine.
Henderson said that groundwater is very clean. Problems arise when the water comes into contact with exposed ore deep inside the mine.
“Sulfur, when exposed to oxygen and water reacts and forms acidic water.”
DEQ’s Abandoned Minelands Program is working on a project to treat the discharge water with hydrated lime and restore Belt Creek.
“It’s calcium hydroxide is what this is and this would be the agent that we add to the water, the acid mine drainage to treat it. And every liter of water that we have coming out would need one gram of hydrated lime.”
The other aim of the project is to study the feasibility of taking the sludge out of the water and re-injecting it into the mine.
“It’s a very common practice back East, their mine workings are bigger than ours so we were curious if we had the physical space available here to potentially inject sludge,” said Henderson.
He also said it may be possible to pump enough water out of the head end of the mine, further reducing the acid discharge and saving water treatment costs.
The Great Falls coal fields of a hundred years ago first fed steamships that plied the waters of the Missouri River. The coal was then used for railroad trains and the smelters located in Great Falls and Anaconda.
The mines follow a horizontal seam of coal that can still be seen in places along the rolling hills east of Great Falls.
Thousands of miners and their families made up towns like Belt, Sand Coulee, Centerville and Stockett. The area is home to both small reclamation projects and the Belt water project, currently DEQ’s biggest.
The goal of the projects: restore land and waterways for wildlife, communities and crops.
DEQ officials say once clean water is restored to impacted streams, it doesn’t take long for nature to bounce back. For instance, once the well-known McLaren Mine Tailings were removed from Soda Butte Creek near Cooke City, wild fish returned to the waterway in short order.
“I think it’s a huge win both ways. The creek comes just up-stream of these acidic discharges and it has excellent water quality, and it’s an excellent fishery just up-stream of these discharges.”
The project, funded by federal government mining cleanup dollars, will cost between $5 million and $6 million.
Henderson hopes to break ground on the water treatment plant in the spring of 2018 and have the plant running by the fall of 2019.