2009-09-21_PERMIT FILE - C1981010 ‎(13)‎

• Permit No: C1981010
• IBM Index Class Name: Permit File
• Doc Date: 9/21/2009
• Doc Name: Trapper G-Pit Landslide Mining Assesment, January 2008
• Section_Exhibit Name: Appendix T
• Media Type: D
• Archive: No

January 15, 2008
3.0 ROCK MASS CHARACTERIZATION
Page 10
Lithologic logs were recorded for all 19 boreholes. The logging procedures followed
AAI core logging guidelines.9 Data collected for each significant interval were the following.
• Rock type and description.
Rock Quality Designation (RQD)10 varies between 0-100 as measured from the length of
intact core pieces greater than 4 inches (10 cm).
Infilling Index (I) varies 1-5 and indicates the type and quantity of infilling in fractures.
A value of 5 is unfavorable indicating thick weak clayey infilling.
Planarity Index (P) varies 1-5 and indicates the planarity of fractures. A value of 5 is
unfavorable indicating flat fractures with no steps or conchoidal shapes.
Roughness Index (R) varies 1-5 and indicates the roughness of fractures. A value of 5 is
unfavorable indicating very smooth fracture surfaces.
• Fracture Frequency Index (FF) varies 1-5 and indicates the number of natural fractures
per meter of core run. A value of 5 is unfavorable indicating highly fracture core run
(>5 fracture/ft).
• Structure Index (FT) varies 1-5 and indicates the predominant type of discontinuity in the
core run. A value of 5 is unfavorable indicating all natural jointing.
• Fracture Durability Index (FD) varies 1-5 and indicates the in situ strength of fractures.
A value of 5 is unfavorable indicating low fracture strengths and friable surfaces.
• Disturbance Index (D) varies 0-1 and indicates the amount of mining disturbance that the
rock mass has.been exposed to. A value of 1 is unfavorable indicating highly disturbed
by mining or landslide.
The RMR system 11,12 was selected because it is based on extensive mining case histories
in low to medium strength rock masses. RMR values are based on five factors: (1) RMRI is a
function of intact UCS rock strength (maximum 15 points), (2) RMR2 is a function of RQD
(maximum 20 points), (3) RMR3 is a function of fracture frequency of naturally occuring
jointing (maximum 20 points), (4) RMR4 is a function of joint condition of infilling, persistence,
and roughness (maximum 30 points), and (5) RMR5 is a function of groundwater condition
(maximum 15 points). The maximum RMR value is 100. RMR values at Trapper Mine are
typically in the range of 55-75. The RMR5 value was always taken as 10 because field
observations of the highwall mining face suggest the rock is normally dry with minor
groundwater seeps; constant flow is rarely observed.
9 Agapito Associates, Inc. (2000), "Core Logging Procedures," Grand Junction, CO, May.
10 Deere D.U. and D.W. Deere, (1988), "The Rock Quality Designation (RQD) Index in Practice," Rock
Classification Systems for Engineering Purposes, ASTM Special Publication 984, Ed. L. Kirkaldie, p. 91-101.
" Bieniawski Z.T. (1989), "Engineering Rock Mass Classifications," Wiley and Sons, Pennsylvania PA, p. 25-95.
12 Bieniawski Z.T. (1993), "Classification of Rock Masses for Engineers: The RMR System and Future Trends,"
Comprehensive Rock Engineering Principles -Practice and Projects, Ed. J.A. Hudson, Vol. 3, p. 553-573.
Agapito Associates, Inc.