2021-09-07_REVISION - M1973021 ‎(7)‎

• Permit No: M1973021
• IBM Index Class Name: Revision
• Doc Date: 9/7/2021
• Doc Name Note: Appendix 1 Geotech Exhibit
• Doc Name: Adequacy Review Response
• From: Aggregate Industries-WCR, Inc.
• To: DRMS
• Type & Sequence: AM7
• Email Name: ECS
• Email Name: MAC
• Media Type: D
• Archive: No

Sillimanitic Gneiss was considered for the global condition, FOSS reported ranging from 1.85
to 2.17 and 1.46 to 1.97 for SLOPE/W and FLAC/Slope, respectively. These results indicate
global stability is adequate for the various bench configurations as all global analyses meet
the minimum State required FOS of 1.25.
Considering smaller segments of the highwall with applied local strength conditions, the
resulting FOSS presented in Table 7-4 vary from 1.21 to 1.58 and from 1.21 to 1.35 for the
SLOPE/W and FLAC/Slope results, respectively. As indicated by the red shading in Table 7-
4, a 30-foot wide mid-slope bench at El. 6,650 feet(i.e., no change in highwall width) does
not meet the minimum State required FOS of 1.25 for the both analysis methods, and a 50-
foot wide mid-slope bench at El. 6,650 feet does not meet the minimum State required FOS
of 1.25 for the FLAC/Slope analysis. Based on these results, an intermediate bench width of
60 feet at El. 6,650 feet results in a FOS of 1.26 or greater, which satisfies State minimum
FOS criteria of 1.25.
Table 7-3. Slope Stability Analyses Results: South Quarry Global Stability
Considering Factor of Safety (FOS)
Bench Width Bench Width Presence of
at El 7000(ft) at El 6650(ft) Case ID Sillimanitic
SLOPE/W FLAC/Slope
Gneiss?
1-1a No 2.00 1.56
30
1-1b Yes 1.85 1.69
1-2a No 2.10 1.75
30 50
1-2b Yes 1.93 1.69
1-3a No 2.34 Note 3
100
1-3b Yes 2.12 1.86
2-1 a No 2.03 1.58
30
2-1 b Yes 1.85 1.64
2-2a No 2.11 1.62
40 50
2-2b Yes 1.94 1.50
2-3a No 2.34 1.87
100
2-3b Yes 2.14 1.91
3-1 a No 2.04 1.75
30
3-1 b Yes 1.86 1.60
3-2a No 2.12 1.71
50 50
3-2b Yes 1.95 1.62
3-3a No 2.35 1.99
100
3-3b Yes 2.15 1.87
37
Aggregate Industries-Morrison Quarry GEI Consultants, Inc.
AM-07 Geotechnical Stability Exhibit November 2020