2023-08-31_ENFORCEMENT - M1982121

• Permit No: M1982121
• IBM Index Class Name: Enforcement
• Doc Date: 8/31/2023
• Doc Name: Rock Failure Analysis and Stability Report
• From: RMR Aggregates, Inc.
• To: DRMS
• Email Name: ACY
• Email Name: THM
• Media Type: D
• Archive: No

K1L D UFF RMR Aggregates, Inc.
U N ❑ E R G R O U N ❑ Rock Failure Analyses and Stabilization Report
E NGIN E E R I N G,INC. Mid Continent Limestone Ouarry
For the RMR Aggregate site, the failure path of the slope could impact quarry facilities on the bench,
so the consequence of failure from moderate to high was evaluated. This correlates with the
recommendation from the DRMS recommendations reproduced in Table 4, corroborating a FOS of
1.5 was considered as the minimum acceptable FOS.
Based on the slope stability results for the west wall, the massive limestone is stable for a variety of
bench slope geometries. Slope stability results for the west face based on the above conditions are
summarized in Table 4.
Table 4. Summary of Factor of safety
for varying bench slope geometry
Bench Slope Geometry Factor of Safety
(Horizontal:Vertical)1 (long-term)
1:1 1.40
1.4:1 1.54
1.67:1 1.63
1. Max bench height of 30 feet
Using the accepted minimum FOS of 1.5, a H:V bench slope geometry of 1.4:1 or larger is deemed
acceptable.
7. JULY 6 SITE RECONNAISSANCE
A site reconnaissance on the West wall was performed on July 6, 2023 with RMRA staff and Ben
Langenfeld of Lewicki &Associates to evaluate the north limit of the upper limestone beds and
formulate a plan across represented disciplines to determine the optimal quarry headwall extent for
long-term slope stability using the modeled long-term slope geometries discussed above. Photos with
detailed captions from the reconnaissance are included in Appendix F.
A site mapping program was performed to collect structure data on the West wall and to determine
the north limit of the upper limestone beds as they pinch out upslope. The bed thickness and bedding
dip of the two upper limestone beds decreases to the north from the quarry headwall as the forelimb
of the monocline rolls over toward the fold axis. Kirkham et al. map the upper limestone beds as
dipping between 38 degrees near the quarry to 24 degrees toward the top of the hill to the north,
which forms dip slopes and tends to control hillside slope topography. Borehole Lynx 05-099 (1966)
drilled vertically in the area of the event identifies dip in the upper 40 feet of the section as 40
degrees. The July 2023 site reconnaissance mapped the upper limestone beds from near the ground
event and northward as the beds pinch out and bedding decreases to approximately 28 degrees.
Appendix F photos document the beds decreasing in thickness at points along the slope. Locations of
bedding dip and dip direction on the top of the massive limestone (contact with the upper limestone
units) and measurement of the presence/thickness of the upper limestone beds are designated on
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