2016-07-14_PERMIT FILE - M2016010 ‎(4)‎

• Permit No: M2016010
• IBM Index Class Name: Permit File
• Doc Date: 7/14/2016
• Doc Name: Adequacy Review Response
• From: Transit-Mix Concrete Co.
• To: DRMS
• Email Name: AME
• Media Type: D
• Archive: No

Transit Mix Concrete Co.
6. Comment: Please provide the SLOPE/W slope stability analysis data from the Norwest
overall slope analysis to allow the Division to duplicate the analysis with Clover
Technology's Galena software for verification purposes.
Response: Modelling inputs are provided in the Exhibit 6.5 addendum.
7. Comment: Please provide the SLOPE/W slope stability analysis models for all conditions
for the bench scale analysis from the Norwest analysis to allow the Division to duplicate the
analysis with Clover Technology's Galena software for verification purposes.
Response: Modelling inputs and an AutoCAD file of the region boundaries are provided
on the attached CD.
8. Comment: Please provide justification for the Phi angle value of 0 degrees used in the
Norwest SLOPE/W slope stability analysis.
Response: The author assumes you are referring to the Phi-B value shown on the
SLOPE/W outputs in Appendix H of the pit wall memorandum. Phi-B is related to
suction and can represent additional strength due to matric suction in soils. This
parameter has been set to zero degrees for the pit wall stability analysis (i.e.,saturated
or near saturated condition).
9. Comment: Please provide justification for the circular failure analysis instead of a wedge
failure analysis used in the Norwest SLOPE/W slope stability analysis.
Response: Rock slope failure mechanisms become similar to those encountered in soil
when there are no dominant or preferred directions of weakness plane.Without the
presence of large-scale structural features to define failure wedges within the pit walls,
the circular failure analysis is deemed to be acceptable.
The west fault is near vertical and oriented perpendicular to the pit walls. It is also a
narrow (less than 2ft) and tight fault zone where is intersects pit walls and so is not
anticipated to create stability issues. The west fault does cut through the east wall of
the North Pit, nearly parallel to the pit wall. However, due to the orientation and
characteristics of the fault combined with the strength of the rock mass within the pit
wall area it is not expected to create a stability concern.
10. Comment: As recommended in Section 6.3 of the Norwest Geotechnical Assessment- Rev.
B, dated January 26, 2015, please commit to conducting further geotechnical assessments
during the initial quarry development to evaluate pit wall design performance and wall
angles.
Response: See Transit Mix memorandum included in Exhibit 6.5.
Hitch Rack Ranch Quarry (M-2016-010)
Response to Comments—July 14, 2016