A possible copper mine at the headwaters of the famed Smith River has passed another hurdle.
On Monday, the state Department of Environmental Quality released a draft Environmental Assessment that says it’s determined that Tintina Alaska Exploration, Inc. will be able to mitigate any possible impacts from its ongoing exploration at the Black Butte Mine.
Potential impacts include the possibility about 20 to 30 percent of the rocks removed could generate acid runoff, sulfide materials in waste rock react with water and oxygen to produce sulfuric acid.
The Canadian-based company has been drilling core samples in a field northeast of White Sulphur Springs for about three years at a cost of about $18 million. Earlier this year, Tintina applied for a permit for a “decline,” which will let it get a better look at whether it’s economically feasible to mine for copper there.
Basically, the decline is a 5,200-foot-long ramp that goes underground. It will be 18-feet high and 18-feet wide on about 45 acres of private property off of Highway 89.
“They want to look at their potential ore body in three-dimensions,” said Warren McCullough, head of the DEQ permitting and compliance division. “They can pull out 10,000 tons for bulk sampling for metallurgical testing.”
DEQ Director Tracy Stone-Manning noted that this is only a preliminary decision, and that they’ll now put the proposal out for public comment.
“This exploration will provide DEQ and the public with hard data and information that can be used if and when we make a final decision on a permit for a mine,” Stone-Manning said.
Based on their core samples, Tintina forecasts that what it calls the “Johnny Lee deposit” could produce a single copper concentrate containing an average of 47 million pounds of payable copper metal per year during a 14-year mine life. That translates to 658 million pounds of copper, which at $3 per pound, would have a value of $1.97 billion.
In the 60-page draft document, Tintina proposes putting the underground materials it hauls out of the decline into two piles lined with a thick, nonpermeable barrier. The “PAG” pile is of Potential Acid Generating materials and is estimated to include about 30 percent of the rock. The remaining materials go into the “NAG” pile, which is the Non-Acid Generating rock.
Water that falls on the rocks will be collected and treated if necessary. The PAG pond would have the capacity to store 1.9 million gallons of water, while the NAG pond would have a 4.1 million gallon capacity.
If Tintina decides it’s not feasible to develop the copper mine, the company will put the PAG rocks back into the decline, cover it with a concrete barrier, then put the other rocks on top of that and reclaim the site. McCullough said that by burying the PAG, it no longer will create acid runoff.
The state already has a bond from Tintina for its sampling and will increase that — if the draft EA is finalized — so that if Tintina doesn’t reclaim the site adequately, the state can do it without incurring costs.
He added that they’re not sure what they’ll do with the PAG and NAG rocks if Tintina wants to further develop the mine.
“We’re taking this one step at a time,” McCullough said. “First they need to see what they’ve got there and probably do some economic studies and that type of thing. We don’t want to get too far ahead of ourselves.”
That, and the entire project, worries Jim Jensen, executive director of the Montana Environmental Information Center. He’s well aware of the long-term negative impacts of acid mine runoff from the Zortman/Landusky mine in northeast Montana and in Butte, where the 900-foot-deep Berkeley Pit, carved out from a copper mine, holds a 30 billion gallon stew of highly acidic water.
Jensen fears a large copper mine at the headwaters of the Smith River will have similar results and contaminate its pristine waters.
“Once again DEQ assures us there will be no harm to the water from a mine proposed in highly acidic rock,” Jensen said. “Their record does not give me confidence.”
He added that, in his opinion, the draft EA doesn’t include any solid data about safeguards for the water quality or quantity.
“This is short on details but long on assurances,” Jensen said.
McCullough, however, said the state is well aware of the concerns regarding Sheep Creek and Coon Creek, which run nearby and flow into the Smith River.
“That’s one reason it took longer than expected to put out this document,” McCullough said. “We took a close look at possible impacts on water quality and quantity.”
The draft EA will be posted on the DEQ web page: www.deq.mt.gov, and copies also can be obtained by writing to the DEQ Environmental Management Bureau, c/o Herb Rolfes, P.O. Box 200901, Helena, MT 59620; calling Rolfe at 444-3841; or sending him an email addressed to DEQTintinaBlackButteCopperProject@mt.gov.
Public comments concerning the adequacy and accuracy of the Draft EA will be accepted until Aug. 26. A public meeting also will be held before the end of the comment period.
Reporter Eve Byron: 447-4076 or email@example.com Follow Eve on Twitter @IR_EveByron