2008-04-30_REPORT - M1973021 (3)

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Figures 3 and 4 are a photo documentary of the features observed in Bench D. 3.3 South Quarry Geotechnical data was collected for the areas mined in 2007. As mining in this expansion to the quarry only started this year, the primary activity for the expansion included overburden stripping and building haul roads. One highwall has been completed (Bench 1, approximate elevation 7000 feet above MSL); however the related bench has not been completed yet being approximately 120 feet wide at the time of the survey. The highwall orientation is approximately north-south and likely represents the average highwall development orientation for the upcoming mining. The type of rock encountered in the highwall is consistent with rock found in other areas of the quarry. The rock of the highwall was fine to medium grained biotite gneiss. No intrusions were • observed in this highwall survey. The gneiss observed in the highwall was moderately to highly weathered, likely due to the • proximity to the original ground surface. The highwall generally displays two prominent joint • sets and a foliation surface. Joint spacing ranges from approximately '/4 inch up to 3 feet. Joint ed l t l . os o c y open surfaces generally are slightly smooth to slightly rough and are moderate When joint surfaces are open or exposed, the joint faces are typically moderately to highly . weathered and display iron staining. The joints generally do not contain any infill material. Foliation spacing ranges from less than one inch up to 2 feet. Foliation surfaces generally are slightly smooth to slightly rough and are moderately open. Across the highwall, the foliation displays relatively similar orientations with anticlinal folding. The anticlinal axis is into in di ti li f h i g pp on a o n t e approximately the same orientation as the highwall, which results the highwall in areas and out of the highwall in other areas. When foliation surfaces are open • or exposed, the aperture is up to one inch and the foliation faces are typically moderately l i ; a weathered with iron staining. The foliation generally does not contain any infill mater however in some cases minor clay infill was observed. • The highwall observed was dry and seepage through the rock is not anticipated. Average RMR values calculated for the rock exposed in the highwall of Bench 1 range from 38 to 55 indicating poor to fair rock. Joint orientation field data and RMR spreadsheets for the • highwalls are included in Appendix A. ~' The Bench 1 scanline was approximately 200 feet long and was separated into 4 discrete ~ sections. Stations 0+00 through 0+50 consisted of biotite gneiss displaying an anticlinal trend. The strike of the foliation ranges from 0 to 10 degrees. Foliation dips range from 28 to 38 degrees. The average spacing of the foliation was approximately 12 to 18 inches and the foliation displays slightly smooth, wavy apertures that are open up to 0.5 inches. The primary joint set strike ranges from 145 to 150 degrees and generally dips from 65 to 75 degrees. The secondary joint set strike ranges from 210 to 220 degrees and generally dips from 72 to 80 degrees. Joint set 1 average spacing was 7 inches and -5- • F:\3919_038\Anmial_Repod_2007\Gcotech_Addcndum_2007Wnnual_Report_2007_Gcotcch.doc • • l _ - - Apri12008