Tintina Resources office in White Sulphur Springs

Tintina Resources has opened an office on the main street of White Sulphur Springs to promote their Black Butte copper mine project.

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A Canadian company wants to test the groundwater near the site of a proposed mine in central Montana, but state regulators are seeking public input because the groundwater could be laced with arsenic.

On Monday, the Montana Department of Environmental Quality published an environmental assessment of Tintina Resources' plan to drill four new deep wells to test the groundwater recharge rates in the area of the proposed Black Butte copper mine northwest of White Sulphur Springs. The assessment is open for public comment.

Environmental groups are sure to comment because the site in this study is adjacent to an unnamed stream that feeds into Butte Creek, a tributary of Sheep Creek.

Montana Trout Unlimited Executive Director Bruce Farling is worried about mining discharge ruining Sheep Creek's high-quality fishery, which augments that of the Smith River 17 miles away.

Three of the new wells would pump water for 30 days from depths of between 200 and 400 feet to learn how quickly the water table drops. The fourth well would monitor groundwater levels.

Tintina has already drilled several monitoring wells near the proposed mine to measure water quality and quantity under its existing exploration permit.

The company's plans have described an underground mineshaft that passes through the water table. To keep the shaft from filling with water, the water would need to be pumped out. These tests would provide the company with an indication of how much water it would need to pump.

The concerning issue for DEQ is that at least one of the wells is expected to pass through an area of rock that contains higher amounts of arsenic.

Measurements at a nearby monitoring well shows arsenic levels in the water exceed the allowable standards set by the Environmental Protection Agency.

Tintina has proposed a plan to collect the water pumped out of the wells in a lined holding pond. The pond would be made big enough to hold slightly more water than they expect to pump from the wells in a 24-hour period.

Then, the mining company would use an irrigation system to sprinkle the pond water slowly over 40 acres. The plan is to complete the test during the summer when vegetation is still growing and sprinkle the water so slowly for six hours each day that it evaporates before it would get into the surface or groundwater. The ground would be allowed to dry for 18 hours each day.

The plan claims this amount of dispersal would keep the arsenic load on the soil below EPA limits.

That plan would change in the event of rain, which would slow evaporation. In that case, the plan would require the company to either temporarily store the water in tanks or stop the pump test.

If they had to stop the 30-day test, they might have to start over.

Additionally, the company would have to construct a larger lined contingency pond if the test has to stretch into the late fall or winter months. Water sprinkling would still continue but at a slower rate.

Farling, with Trout Unlimited, is having a hydrologist check the modeling used to calculate the evaporation rates.

“They've been telling us that no matter what they do, it won't affect the water. If they were so sure, why do they need the pump test now?” Farling said. “They're depending on land application rates and modeling to work up there. In our experience, mining companies always get it wrong and end up with more discharge than what the land can take.”

Because the public comment period closes July 21, it's likely that the project will be pushed into the colder months.

DEQ spokesman Chris Saeger said going through the comments and finalizing the decision will take time.

As Tintina has worked with DEQ on finalizing the EA, they have brought an Australian mining company to recent meetings.

Sandfire Resources is an Australian copper mining and exploration company that opened its first mine near Perth in 2012.

Saeger could not confirm whether Sandfire Resources was taking over the Black Butte operation or just joining as a financial partner.

Tintina Resources spokeswoman Nancy Schlepp previously told the, Chronicle that Tintina was in the hunt for strategic partners. Calls to Schlepp Monday were not returned.

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