2025-09-29_REVISION - M1980244 ‎(4)‎

• Permit No: M1980244
• IBM Index Class Name: Revision
• Doc Date: 9/29/2025
• Doc Name Note: 2 VLF Expansion Design Report
• Doc Name: Adequacy Review Response #2
• From: CC&V
• To: DRMS
• Type & Sequence: AM14
• Email Name: ERR
• Email Name: ZTT
• Media Type: D
• Archive: No

TABLE OF CONTENTS

1. INTRODUCTION ...................................................................................................................... 1
1.1. Project Description ......................................................................................................... 1
1.2. Scope of Work ................................................................................................................ 3
2. SITE CHARACTERIZATION ....................................................................................................... 3
2.1. Location and Topography ............................................................................................... 3
2.2. Climate ........................................................................................................................... 3
2.3. Underground Workings .................................................................................................. 3
2.4. Seismicity ........................................................................................................................ 4
2.5. Subsurface Conditions .................................................................................................... 5
3. GEOTECHNICAL CHARACTERIZATION ..................................................................................... 5
3.1. VLF2 Phase 3 Expansion Site Investigation (NewFields, 2020) ........................................ 5
3.2. Valley Leach Facility Expansion Test Pit Program (Newmont, 2023) ............................... 5
3.3. Valley Leach Facility Expansion Geophysical Survey (IGES, 2023) ................................... 6
3.4. Laboratory Testing Program ........................................................................................... 6
3.4.1. Natural Moisture .............................................................................................. 7
3.4.2. Index Properties and Material Characterization .............................................. 7
4. VALLEY LEACH FACILITY DESIGN ............................................................................................. 8
4.1. General ........................................................................................................................... 8
4.2. Staged Construction ....................................................................................................... 9
4.3. Valley Leach Facility Foundation ................................................................................... 10
4.3.1. VLF2 Phase 4 Stage A ..................................................................................... 10
4.3.2. VLF2 Phase 4 Stage B ..................................................................................... 11
4.3.3. VLF1 Phase 6 Stage A ..................................................................................... 11
4.3.4. VLF1 Phase 6 Stage B ..................................................................................... 11
4.4. VLF1 Phase 6 Process Solution Storage Area ................................................................ 12
4.4.1. PSSA Embankment ......................................................................................... 12
4.4.2. Lined PSSA Basin ............................................................................................ 13
4.4.3. High-Volume Solution Collection Recovery System ....................................... 13
4.5. Lined Pad Expansion Area ............................................................................................. 14
4.5.1. Leak Detection System ................................................................................... 14
4.5.2. Composite Liner System ................................................................................. 14
4.6. Solution Collection System ........................................................................................... 15
4.6.1. High-Volume Solution Collection System ....................................................... 15
4.6.2. VLF2 Phase 4 Infiltration Gallery .................................................................... 15
4.6.3. Low Volume Solution Collection System ........................................................ 16
4.7. Appurtenant Structures ................................................................................................ 16
4.8. Reclamation/Closure .................................................................................................... 1 6
4.9. Technical Specifications ................................................................................................ 16
5. GEOTECHNICAL EVALUATION .............................................................................................. 17
5.1. Stability Evaluation ....................................................................................................... 17
5.1.1. Model Development ...................................................................................... 17
5.1.2. Design Ground Motions ................................................................................. 18