(CN) — The Montana Department of Environmental Quality failed to properly evaluate the environmental impacts of a new mining technique to be used in a proposed copper mine in eastern Montana, attorneys argued in state district court Friday.
The proposed underground Black Butte copper mine near White Sulphur Springs, Montana, would extract 440 tons of ore daily and generate 12.9 million tons of tailings from an 1,800-acre mine near the headwaters of the Smith River — one of Montana’s most pristine rivers.
The Montana Department of Environmental Quality issued a mine operating permit to Tintina Resources Inc. in April 2020, for the company to pursue the Johnny Lee copper deposit — one of the largest copper deposits Montana has ever seen.
The state was sued in June 2020 in Meagher County District Court over the state’s alleged failure to properly analyze the mine’s long-term effects. Jenny Harbine, an attorney for EarthJustice, a nonprofit law firm in Bozeman, Montana, argued Friday before Richland County Judge Katherine Bidegaray that the state did not properly analyze the nitrogen content of effluent water pumped out of the mine, nor did the state take into account Tintina’s plan to build an above-ground tailings impoundment using new and untested methods.
EarthJustice represents plaintiffs Trout Unlimited, Montana Environmental Information Center, American Rivers and Earthworks.
Tintina proposes to mix the treated copper mine tailings with cement and store them in a tailings impoundment. Harbine argued that this is an untested method and the Montana Department of Environmental Quality failed to properly determine what level of mine waste and cement would be strong enough to protect the environment.
The Montana Department of Environmental Quality is tasked with researching all aspects of the effects of metals mining in the state, and the courts are to give the agency deference in their decision making.
In this case, Harbine said, the state “fell well short of those standards” in its review of the Black Butte copper mine and its permit. In order to balance the stability of the cemented tailings with the amount of time required for each layer to dry, new layers would be added every seven to 30 days. The state and Tintina say this process would form a solid, hard mass that would be impermeable to water and would lock in hazardous materials left over from the copper-ore mining process.
Harbine said the state of Montana didn’t study how the cemented tailings facility would perform as it suggests, as the proper cement mixture has never been field tested.
One of EarthJustice’s main arguments was that this new method of cemented mine tailings may not form a solid, stable mass of mine waste that is impermeable to the elements.
Under Tintina’s mine permit from the state, the top layer of mine waste will not have set before wet tailings are placed on top of them “layer after layer after layer,” Harbine said. “There is no analysis that defendants can point to” in terms of how long it takes tailings to set.
“Without this timeframe, DEQ’s vague timeframes are meaningless,” Harbine said. “There’s just no record evidence for set time of (cemented) tailings.”
“There are more questions than answers” of whether Tintina struck the right balance of mixtures and timing, Harbine said, adding “it’s important that Tintina gets this right.”
Montana has a long history of mines that failed to contain leftover waste, such as the defunct Zortman Landusky mine, which a bankrupt mining company abandoned and left the state to pay cleanup costs.
“These were mines that DEQ permitted and predicted to be safe, and in each of these cases they were wrong,” Harbine said, “leaving irreversible contamination and incalculable loss.”
