2008-04-15_REVISION - M1980244 ‎(192)‎

• Permit No: M1980244
• IBM Index Class Name: REVISION
• Doc Date: 4/15/2008
• Doc Name: VOL IV APP 5 Attachment 2 Globe Hill Mine Slope Design
• From: CC & V
• To: DRMS
• Type & Sequence: AM9
• Media Type: D
• Archive: No

• GHMXSIopeEvaluation
RQD values were computed for the 22 drill holes for which RQD data were reported. The average RQD
results for each borehole are summarized in Table 4, and are plotted for the GHMX area in Plate 3. The
RQD in all drill holes was not strongly dependent on sample depth. The exception is GHT-07-02, where
the RQD is controlled by approximately 20% of the recovered core being intact anhydrite, which is,
however, very weak.
There is a strong variation in RQD over the project, with the lowest RQD (5%) in the northeast, and the
highest (70%) in the southwest. The lowest RQD values are on the periphery of the Globe Hill Pipe,
where the volcanics are rubblized, and anhydrite is absent.
The average RQD for the Cripple Creek diatremal rock is 70%. Accordingly, almost all of the wall of
the proposed GHMX will be located in rock that is considerably more fractured, and hence considerably
weaker, than the rock in which all previous surface mines (except the original Globe Hill mine) have
been developed in the Cripple Creek mining district.
2.6 Fracture Intensity
The fracture intensity is measured as the number of fractures in each foot of recovered core. In cases
where core is rubble, or is missing, it is assumed that there is greater than 10 fractures per foot, and the
numerical value of 11 fractures per foot is used as a maximum. Thus the available range is from 0 to 11
• fractures per foot.
Fracture data was collected in
presented in Table 4, and is p
with high fracture intensity in
the more intact material to the
2.7 Intact Rock Strength
a total of 22 holes. The average fractures per foot for each hole is
resented in Plate 4. The distribution is similar to the RQD distributions,
the rubblized material to the northeast, and moderate fracture intensity in
southwest.
Samples of intact rock were taken from a total of 9 coreholes. Samples were taken from two of the
coreholes for unconfined compressive strength testing, with the results presented in Table 1. In the other
seven holes unconfined compressive strength was estimated from point load tests. The results are
presented in Table 2. The average unconfined compressive strength test results are presented in Table 4,
and are presented in Plate 5.
The intact rock varies from very weak (UCS = 415 psi) in the northeast quadrant of the GHMX mine to
relatively strong (UCS = 10,150 psi) in the southwest quadrant. By way of comparison, the average
UCS of diatreme rocks in the rest of the district is approximately 14,500 psi. Globe Hill represents the
weakest rock that has been mined by CC&V.
• ~ This is normal; the higher the fracture intensity, the lower the aggregate length of pieces that exceed 4" in length, and thus the lower the
RQD.
Report 1385E.20071126