HELENA—Today, the Department of Environmental Quality (DEQ) and the Department of Natural Resources and Conservation (DNRC) took steps to move the review process forward for the Black Butte Copper Mine Project proposed by Tintina Montana, Inc. (Tintina). The proposed project consists of an underground copper mine to be located in west-central Montana, approximately 15 miles north of White Sulphur Springs.
DEQ has issued a Final Environmental Impact Statement (EIS), which was prepared under the authority of the Montana Environmental Policy Act (MEPA), analyzing the potential impacts of the proposed project. The Final EIS is not a decision document, but will help DEQ make informed decisions with respect to permit applications submitted by Tintina, including applications for a hard rock mining operating permit, an air quality permit, and a surface water discharge permit.
“We take our responsibility in conducting environmental review of permit applications very seriously,” said DEQ Director Shaun McGrath. “The Final EIS represents a thorough evaluation of the potential impacts of this proposed project. Our review was informed not only by the DEQ scientists working on the project, but also by the thousands of comments submitted throughout the process. It was truly an extensive effort and we appreciate the public’s interest and participation.”
The MEPA analysis revealed a potential for reduction in flow in Coon Creek due to groundwater being diverted by mining activity. To ensure compliance with the Montana Water Quality Act, Tintina must mitigate this potential impact by augmenting flows in Coon Creek. This flow mitigation requires Tintina to apply to DNRC for water permits and water right changes. DEQ and DNRC have worked closely to ensure the environmental review and water rights processes are aligned to the extent possible.
DNRC has issued Preliminary Determinations to Grant two water permit applications and six water right change applications related to the project. One permit application requests to divert groundwater from the mine workings for industrial use around the mine site. The other permit would allow Tintina to divert and temporarily store water during high spring flows for release later in the year.
The six water right change applications would allow existing irrigation rights to be marketed on an annual basis to Tintina to mitigate impacts to surface water from Tintina’s groundwater appropriation.
“The source aquifer is hydraulically-connected to area streams,” noted DNRC Director John Tubbs. “When Tintina pumps groundwater out of the mine, our analysis shows that surface water will be depleted, and it’s critical that those depletions are replaced by another water supply so that existing water users are protected.”
Tubbs said the mitigation plans will assure no net increase in stream depletions due to Tintina’s groundwater pumping. “Our foremost responsibility is to ensure no adverse effects to existing water rights,” he said.
Through the MEPA analysis, DEQ identified the Agency Modified Alternative as the agency’s preferred alternative. This alternative includes all elements from Tintina’s Proposed Action, with one additional component: backfilling additional areas of the underground mine workings. The Proposed Action involves a mining method called “drift-and-fill” where mining happens incrementally and areas are continuously backfilled as mining activity moves forward. DEQ proposes that Tintina backfill more areas than originally proposed, including certain access ramps and other openings located within sulfide zones. The mined-out areas would be backfilled with cemented paste tailings, which is a paste-like material created by adding cement, slag and/or fly ash to mine tailings. Water does not easily flow through cemented paste tailings, so the use of this material minimizes the potential for new groundwater flow patterns to develop across the reactive materials in these zones. While the analysis has shown that the Proposed Action would comply with water quality standards, DEQ has selected the Agency Modified Alterative to further protect water quality.
Following today’s release of the Final EIS, DEQ will issue its final decision and rationale in a Record of Decision (ROD). The ROD identifies what the decision is, the reasons for the decision and any special conditions surrounding the decision or its implementation. DEQ cannot issue the ROD until at least 15 days after the publication of the Final EIS.
The Final EIS has been posted on DEQ's website at: http://deq.mt.gov/Public/eis The permit applications are also available for the public to view by visiting DEQ’s website at: http://deq.mt.gov/Land/hardrock/tintinamines
Copies of the Preliminary Determinations to Grant documents and other information related to the Tintina applications are available on the DNRC Web at: http://dnrc.mt.gov/divisions/water/water-rights/new-appropriations-program
For DEQ: Rebecca Harbage, Public Policy Director, 406-444-2813, firstname.lastname@example.org
For DNRC: John Grassy, Public Information Officer, 406-444-0465, email@example.com