DEQ Press Releases

Driscoll, Paul

USFS and DEQ Approve Benbow Mineral Exploration Portal

Dean, Montana – The Custer Gallatin National Forest and Montana Department of Environmental Quality have prepared an Environmental Assessment and Decision Notice and Finding of No Significant Impact for Stillwater Mining Company’s Benbow Exploration Portal and Support Facilities Plan of Operations for Mineral Exploration.

This decision approves construction of an underground exploration decline and related surface support facilities approximately four miles southwest of Dean in Stillwater County.

Surface infrastructure includes a portal pad, an access road, waste rock management facilities, water wells, a water treatment plant and a water disposal system.  Excess water generated from mineral exploration would be collected and treated to remove nitrogen to comply with state water quality standards.  Two potential water disposal options are authorized:  1) Injection well disposal; or, 2) Land Application Disposal system.  Injection well disposal is the preferred option and would consist of injecting treated water into the Environmental Protection Agency-approved receiving groundwater aquifer.  Land Application Disposal would be utilized in the event that the injection well disposal results in water quality violations or if the injection well does not function.  Land Application Disposal would consist of storing treated water in a pond and using pivot sprinklers to evaporate and apply treated water across meadows in the Benbow area during summer.  This decision also authorizes use of waste rock to surface roads and campsites, cap historic chrome mine tailings and create a new parking area for the Chrome Lake Jeep Trail trailhead.

Work is scheduled to begin in September 2015 with construction of an access road and other surface support facilities.  Additional underground work is expected to continue for approximately three years.  Stillwater Mining Company is expecting to start hauling and placing gravel and clearing trees in the area over the next few weeks.  Forest users should expect truck traffic and short delays on the Benbow Road #2414.

Project information is available online at: Project information is also available for review at the Beartooth District or upon request.  If you have information needs or questions, please contact Dan Seifert, Interdisciplinary Team Leader, at 6811 U.S. Highway 212, Red Lodge, MT; phone 406-446-2103, e-mail:

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