REP00670

• Permit No: M1988112
• IBM Index Class Name: Report
• Doc Date: 7/14/1993
• Doc Name: APPENDIX B CONE PENETROMETER TESTS
• From: Battle Mountain Resources
• To: DMG
• Media Type: D
• Archive: No

Battle Mountain Resources, Inc.
06 July 1993
Page 7
3.0 EVALIIATION OF GEOTECHNICAL DATA
Upon completion of the field program, results were inter-
preted using a computer program which determines tailings
behavior according to the specific characteristics of the
' tailings as measured in the field.
Tabulated data was based on values averaged over a depth of
0.25 meters and therefore the influence of extreme values was
minimized. Due to this averaging technique, values of
equivalent density (Eq-Dr), phi angle (phi), Standard
Penetration Test (SPT), undrained shear strength (SU), and
cyclic stress ratio (CSR) may vary from results obtained
from laboratory testing on specific samples. From a geotech-
nical standpoint, this method is preferred over the
conventional intermittent sampling and testing program
' which yields data at discrete points which may not be
representative of the tailings profile in terms of behavior.
For the evaluation of thin lenses or layers; equally
important for geotechnical studies, the digital PCPT data
should be reviewed.
Solution fluids represented only degrees of saturation and a
water table condition was not apparent. A depth to water of
100 feet was utilized for all interpretations.
For determination of Su values, an Nk factor (empirical
' relationship between cone tip resistance and 5u) of 29 was
used. Nk is generally obtained from empirical correlations.
' Reference undrained shear strengths are usually measured from
field vane tests although half the unconfined compression
test is often used.
i Based on the interpreted PCPT profiles, the tailings at the
site primarily behave as sandy silts to clayey silts with
isolated silty sands and sands. In the granular deposits,
' equivalent density was typically less than 40 percent and the
phi angle ranged from 32 to about 38 degrees. Undrained
shear strength for the cohesive deposits averaged 0.2 to 0.6
' tons per square foot (tsf).
SPT N values ranged from about 5 to 15. SPT N1 values ranged
from about 5 to greater than 50. C5R varied from about 0.09
' to greater than 0.50 with an x value of 7.5 blows per foot
for Seed's correction with regard to SPT N1 values.
' Interpretative cone penetration test data for each sounding
in terms of undrained shear strength and cyclic stress ratio
is presented as Appendices B and C, respectively.
' Based upon the depositional history of the tailings, grain
' TERRA TECHNOLOGIES -SOUTHWEST, INC.