2023-08-03_PERMIT FILE - M2023025 ‎(29)‎

• Permit No: M2023025
• IBM Index Class Name: Permit File
• Doc Date: 8/3/2023
• Doc Name Note: Exhibit S - Slope Stability Report
• Doc Name: Application
• From: J & T Consulting Inc.
• To: DRMS
• Email Name: RDZ
• Email Name: MAC
• Email Name: AWA
• Media Type: D
• Archive: No

Table 1 — Soil Properties
Description Max dry Saturated Cohesion Internal
density Density (psf) Friction
cf c Angle
Clay 107 130 50 24
Sand and Gravel 110 125 0 35
Weathered 125 141 100 18
Bedrock
Stable Bedrock 125 141 2000 20
Slurry Wall 100 110 0 45
DESIGN ANALYSIS AND CRITERIA
The proposed mining slopes were analyzed using Clover Technologies Galena Slope
Stability Analysis System, version 7.2. Galena was designed to analyze the slope stability
of earth embankments subjected to several critical situations that may occur during the
life of the embankment. For this project, five cases were identified as critical during the
mining operation. Static and pseudo-static conditions were analyzed in each case.
Pseudo-static peak acceleration factors (peak horizontal acceleration, or PHA) were
taken from USGS information for the western United States. The 2% probability of
exceedance in 50 years (the most conservative) was used. The USGS peak acceleration
map is included in Appendix E. A peak acceleration factor of 0.10 x gravity was taken
from this data. A conservative earthquake loading coefficient of 0.50 x PHA is often used
for slope stability analyses (50% of PHA). We used an even more conservative approach
and used 70% of the PHA for this area for our earthquake loading coefficient. Hence, 0.70
x 0.10 = 0.07.
All mining side slopes will be 2H:1 V, and all reclaimed slopes will be 4.5H:1 V.
The locations of the cases are shown on the case location map included in Appendix A.
Case SS-1 — Gas Line West of Pit.
The mining operation is adjacent to a gas line on the west side of the pit. The proposed
setback for mining is 53 feet from the gas line. The mining depth was assumed to be 38
feet in this area based on bore log information.
Case SS-2— Gas Line North of Pit.
The mining operation is adjacent to a gas line on the north side of the pit. The proposed
setback for mining is 91 feet from the power poles/lines. The mining depth was assumed
to be 34 feet in this area based on bore log information.
IHC Scott,Inc.—Bernhardt Sand and Gravel Pit
Slope
J&T Consulting, Inc. Stability Analysis
2