Environmental Impact Statement for Stillwater Mining Company East Boulder Mine Amendment

18 February 2022 Environmental Impact Statement for Stillwater Mining Company East Boulder Mine Amendment Environmental Impact Statement for Stillwater Mining Company East Boulder Mine Amendment - Lewis Gulch Tailings Storage Facility and the Dry Fork Waste Rock Storage Area 18 February 2022 Open 2/18/2022 3:00 PM MST Type Request for Proposal Close 3/25/2022 3:00 PM MDT Number DEQ-RFP2022-122005 Currency US Dollar Sealed Until 3/25/2022 3:00 PM MDT Payment Terms 0% 0, Net 30 18 February 2022 Contacts Vicki Woodrow VWoodrow@mt.gov Phone +1 406-444-3101 18 February 2022 Commodity Codes Commodity Code Description 1602 Environmental Services - Assessments 18 February 202218 February 202218 February 2022 mailto:VWoodrow@mt.gov DEQ is conducting the completeness and compliance review of the Stillwater Mining Company’s amendment application for Operating Permit No. 00149 issued by DEQ

and the East Boulder Mine Plan of Operations approved by the Custer Gallatin National Forest. The proposed amendment would be Amendment 004. DEQ is seeking a third-party Contractor to assist DEQ and the FS in preparing a joint environmental impact statement analyzing the potential environmental impacts of authorizing the expansion of the East Boulder Mine to construct and operate the Lewis Gulch Tailings Storage Facility and the Dry Fork Waste Rock Storage Area along with various other operational facilities to support the expansion in accordance with the Montana Environmental Policy Act and the National Environmental Policy Act. The EIS must comply with MEPA, Section 75-1-101, et seq., Montana Code Annotated (“MCA”), the Metal Mines Reclamation Act (Section 82-4-301, et seq., MCA), and the Administrative Rules of Montana (“ARM”) pertaining to MEPA. The joint environmental review must also comply with the National Environmental Policy Act as amended by the Environmental Quality Improvement Act of 1970, 42 USC 4321 et seq. and all other applicable laws, Executive Orders, regulations, and direction. Description