2024-02-01_REVISION - M1973021 ‎(2)‎

• Permit No: M1973021
• IBM Index Class Name: Revision
• Doc Date: 2/1/2024
• Doc Name Note: Adequacy Response 1
• Doc Name: Adequacy Review Response
• From: Holcim/HDR
• To: DRMS
• Type & Sequence: TR9
• Archive: No

Geotechnical Stability Exhibit
Engineering Evaluation of Highwall Design for the South Quarry of the Morrison Quarry

January 2024 | i
Contents
1 Introduction ........................................................................................................................ 3
1.1 Purpose and Scope ................................................................................................... 3
1.2 Site Description ......................................................................................................... 3
2 Geologic Conditions ........................................................................................................... 6
2.1 General Geology ....................................................................................................... 6
2.2 Morrison Quarry Geology .......................................................................................... 7
3 Field Evaluations ................................................................................................................ 8
3.1 Annual Quarry Inspections ........................................................................................ 8
3.2 2022 Geotechnical Borings ........................................................................................ 8
3.2.1 Geophysical Evaluations ................................................................................ 9
4 Laboratory Testing ........................................................................................................... 10
4.1 Previous Testing ...................................................................................................... 10
4.1.1 Historic Strength Testing .............................................................................. 10
4.2 Recent Testing ........................................................................................................ 12
4.2.1 Recent Strength Testing .............................................................................. 12
4.2.2 Aggregate Property Testing ......................................................................... 15
4.2.3 Petrographic Analysis .................................................................................. 16
5 Design Methodology ......................................................................................................... 18
5.1 3-D Geologic Model ................................................................................................. 18
5.2 Bench Stability ......................................................................................................... 18
5.2.1 Hoek-Brown Parameters .............................................................................. 18
5.2.2 Kinematic Analyses ...................................................................................... 24
5.2.3 Slope Stability Analyses ............................................................................... 26
6 Quarry Geometry Recommendations ............................................................................... 29
6.1 Kinematic Stability Results ...................................................................................... 29
6.2 Slope Stability Results ............................................................................................. 29
7 Limitations ........................................................................................................................ 30
8 References ....................................................................................................................... 31

Figures
Figure 1: Project location of the Morrison Quarry ....................................................................... 4
Figure 2: Approximate extents of mining cells within Morrison Quarry ........................................ 4
Figure 3: Geologic map of project area ...................................................................................... 7
Figure 4: Suggested Value of D based on excavation method (Hoek, 2000) ............................ 20
Figure 5: Values of constant mi for intact rock by rock group (Hoek, 2000) .............................. 20