Hard Rock Mining Bureau

Amendment 004
Stillwater Mining Company (Stillwater) East Boulder Mine proposes a major amendment to Operating Permit #000149 for the addition of the Lewis Gulch Tailings Storage Facility (LGTSF) and the Dry Fork Waste Rock Storage Area (DFWRSA). Construction of these facilities will provide Stillwater with the tailings and waste rock storage capacity needed to continue to mine the JM Reef in the near term. A summary of the facilities is provided below, and detailed information is in the attached Amendment 004 Plan of Operations (POO). The LGTSF is proposed to be constructed along the west end of the existing East Boulder tailings storage facility in the general area of the current borrow pit. Infrastructure relocation is proposed for 2028 with lining to the basin mid-point in 2030 and lining to the top in 2033. The proposed LGTSF footprint will encompass 87.81 acres an additional 38.9 acres of disturbance associated with roads and infrastructure will be disturbed resulting in a total of 126.71 acres. The LGTSF is expected to provide storage for 5.8 million cubic yards of material which should provide storage at the current mining rate until 2043 to 2045. The DFWRSA is proposed to be constructed to the north of the current mine site. The proposed DFWRSA footprint will encompass 57.02 acres with an additional associated disturbance of 38.53 for a total of 95.55 acres. Of the 95.55 Acres to be disturbed 45.99 are USFS and 49.56 are privately owned by SMC. The DFWRSA will be built in three stages with construction stages proposed to begin in 2025, 2028, 2035. Infrastructure to support construction of the waste rock facility is expected to be constructed in 2024. Total storage will be 5.4 million cubic yards of waste rock which at the current mining rate should provide waste rock storage until 2036 to 2047. Both facilities will have HDPE lined underdrain collection water management systems.

Amendment 008
ES Stone and Structure, Inc. (ES Stone) filed an application for an amendment (008) with the Department of Environmental Quality to reduce the number of sites from 21 to 8 by the removal from the permit of 3 sites (currently Sites #6, 8, and 9) that were withdrawn during the permitting process, 4 sites (currently Sites #3, 5, 7, and 10) that have had full bond release, and the combination of two sites: 1) Current Sites #13, 14, 16, 17 and 21 would be combined to proposed Site #6 and 2) Current Sites #18 and 19 would be combined to proposed Site #7. Additionally, permitted disturbance area would be added to Site #1 and proposed Site #7. Site #1 is located in Golden Valley County: Township 6 North, Range 19 East, Sections 16 & 17. Proposed Site #6 is located in Wheatland County: Township 8 North, Range 15 East, Sections 34 & 35 and Township 7 North, Range 15 East, Sections 02 & 03. Proposed Site #7 is located in Cascade County: Township 22 North, Range 01 East, Sections 27, 28, & 29 and Township 22 North, Range 02 East, Sections 25, 26, & 30. Mining on Site #1 and proposed Site #6 would expand the current practice of excavating surface sandstone. Mining would be to an average of 10 feet below ground surface. Rocks would be quarried with an excavator and then transported to a palleting/staging area using a skidsteer loader. The palleted rock would be loaded onto trucks for shipping off-site. Mining on proposed Site #7 would expand current the practice of harvesting surface sandstone rocks. The depressions left by rock removal would generally be about one foot deep. Surface rock would continue to be removed using hand tools, an excavator, or backhoe and transported to a palleting/staging area using a skidsteer loader. The palleted rock would be loaded onto trucks for shipping off-site. The amendment would add about 3,264 acres to the current operating permit area of about 5,686 acres.

Amendment 017
On March 30, 2020 Golden Sunlight Mine, Inc. (GSM) submitted to the Department of Environmental Quality (DEQ) an application to amend Operating Permit No. 00065. The amendment would allow GSM to reprocess tailings recovered from Tailings Storage Facility 1 (TSF-1) over a period of approximately 12 years using conventional excavation, loading, and conveyance equipment. The 26.2 million tons of tailings at TSF-1 cover an area of approximately 190 acres. Tailings would be recovered from TSF-1, then mixed with water to produce a slurry that would be pumped to the Flotation Plant in the existing Mill Building. The Flotation Plant would process approximately 6,400 tons per day of tailings. The Flotation Plant will allow recovery of residual gold values, reduce reactivity of the reprocessed tailings, and produce a sulfidic concentrate for market at a rate of approximately 455 tons per day. GSM would use the Mineral Hill Pit as a repository for disposal of reprocessed tailings. For final reclamation, a growth media cover will be placed on the tailings surface and seeded to control dust and minimize infiltration of precipitation. Flotation tailings fill material in the Mineral Hill Pit will have a surface area of approximately 35 acres. Implementation will not require a change in the approved water management system for the Mineral Hill Pit. Flotation tailings process solution combined with existing Mineral Hill Pit seepage and the bedrock aquifer will continue to be managed in accordance with the current approved system. GSM would continue to maintain the cone-of-depression in the groundwater table surrounding the Mineral Hill Pit through use of the underground sump. The existing dewatering system will effectively control seepage water from the tailings, ultimately pumping the sump water to TSF-2.

On February 5, 2021, GSM submitted a modification to the proposed amendment application. This modification would relocate the Re-Pulping Facility and related infrastructure, as well as update the associated plans for the operation and reclamation of that facility. On February 10, 2021, DEQ issued a determination that the modification does not constitute a substantial change to the amendment application nor the compliance determination that DEQ issued on October 26, 2020. The Modified Final Application will be the Proposed Action analyzed in the Environmental Impact Statement (EIS).

Modified Final Application
Modification Determination

Amendment 002
On February 27, 2020, GCC Three Forks, LLC, Geyser Site, filed an application with the Department of Environmental Quality for an amendment to Operating Permit No. 00184. The site is approximately 6.5 miles southeast of Geyser, MT near Highway 87. The amendment would authorize the quarrying of gypsum on Department of Natural Resource and Conservation (DNRC) land in Sections 2, 3, 10 and 11, Township 16 North, Range 10 East. The proposed amendment area would cover a total of 377 acres. About 45 acres would be disturbed, in addition to the 37 acres already permitted for disturbance over the life of mine. The mining allowed under the amendment is estimated to add about three years to the life of mine

Amendment 001
On May 11, 2020, Little Bear Construction, Inc. filed an Amendment Application (001) with the Department of Environmental Quality to add acreage currently being mined for limestone and removes the industrial site from the permit boundary. The Drummond Quarry is located north of Interstate 90, approximately four miles west of Drummond, MT.

Montana Frontier Sandstone, LLC (MFS) has filed an application with the Department of Environmental Quality for an operating permit under the Metal Mine Reclamation Act. The operating permit would authorize a quarry mine operation for the purpose of recovering sandstone for masonry and landscape use. The proposed site, the Jones Quarry, is located about 5 miles southwest of Harlowton, MT in Section 10, Township 7 North, Range 15 East, in Wheatland County for a total permit area of about 40 acres. MFS currently operates in this location under a Small Mine Exclusion Statement and needs an operating permit due to proposed expansion of the site. MFS proposes to disturb approximately 30 acres over a life of mine of about 25 years. The site is on private land and would employ 10-14 seasonal employees.

On February 28, 2020, an application for a Hard Rock Mining Operating Permit was submitted by Potentate Mining, LLC (Potentate) for a site located in Granite County. Potentate filed the application with the Department of Environmental Quality for an operating permit under the Metal Mine Reclamation Act. If approved, the operating permit would authorize a placer mine operation for the purpose of recovering sapphires and a minor amount of placer gold. The proposed site is located about 22 miles southwest of Philipsburg, MT in Section 15, and parts of Sections 16, 17, 20, 21 and 22, Township 6 North, Range 16 West, in Granite County for a total permit area of about 2,800 acres. Potentate currently operates in these locations under an Exploration License and Small Mine Exclusion Statement and needs an operating permit due to proposed expansion of the site. Potentate proposes to disturb approximately 2,321 acres over a life of mine of about 30 to 40 years. The site is on private land and would employ up to 24 full and part time employees.

On July 14, 2020, an application for a Hard Rock Mining Operating Permit was submitted by C3 Limited Liability Company (C3) for a site located in Granite County. C3 filed the application with the Department of Environmental Quality for an operating permit under the Metal Mine Reclamation Act. If approved, the operating permit would authorize a placer mine operation for recovering sapphires. The proposed site is located about 22 miles southwest of Philipsburg, MT in parts of Sections 16, 17, 20, and 21, Township 6 North, Range 16 West, in Granite County for a total permit area of about 376 acres. C3 currently operates in these locations under an Exploration License and Small Mine Exclusion Statement and needs an operating permit due to proposed expansion of the site. C3 proposes to disturb approximately 174 acres over a life of mine of about 20 years. The site is on private land and would employ up to 4 full and part time employees. C3 sells washed gravel and sapphire concentrate it produces to Cooney’s Sapphire Village Inc. (CSVI). CSVI would employ up to 36 full or part time employees..