2013-01-31_REPORT - M1973021 (2)

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be expected in this area. Raveling from this zone should be retained on the bench below the highwall and is anticipated to cause only local operational delays. • Stations 19 +60 through 26 +80 were unmappable due to nearly complete debris and rubble coverage. The condition of the highwall is unknown in this section. Figures 10 through 12 are photo documentaries of the features observed on bench 6640. 4.0 RESULTS AND DISCUSSION Observations of the North Quarry indicate little change in the finished slopes since January 2012. Local rock sloughing was observed and classified as minor based on rock accumulations observed on bench surfaces throughout the North Quarry. The condition of the remaining North Quarry is anticipated to remain stable with only small scale rockfall expected to occur. Observations of the Central Quarry indicate little change in the finished slopes since January 2012. Partial reclamation work will continue in 2013 and will consist of continued placement of stripped material within the quarry below approximate elevation 6500 and material pushed into the pit on the south highwalls. Local rock sloughing was observed and was classified as minor based on rock accumulations observed on bench surfaces throughout the Central Quarry. The general condition of the highwalls is anticipated to remain stable with only small scale rockfall expected to occur. A minor tension crack was observed in the south slope and appears to be a result of localized movement or settlement and is not anticipated to cause large scale movement. Slope movement in this area would result in deposition at the base of the Central Quarry where no ongoing mine work is planned in 2013. The baseline rock conditions described in Amendment 3 to Mining Permit M- 1973 -021 are "competent" for granite or biotite gneiss and "poor" for shear zones or highly to extremely weathered zones that have the potential to decrease the stability of the slope. The conditions observed in highwalls mined in 2012 in the South Quarry indicate that the rock is predominately "competent" with a "poor" area located along the north portion of the highwall of bench 6700. Additional localized areas of "poor" rock were observed in the highwalls. Generally, the localized areas of "poor" are located near the end of highwalls or in areas of initial highwall development and several are anticipated to be "competent" once further rock is removed for processing. Over the majority of the quarry no features were observed that are anticipated to cause large block size failures. Markland (stereonet) orientation data indicates very low probability of wedge or toppling failures. Markland orientation data also indicates a low probability of plane failure; the plane failures are most probable on the foliation surface when it dips out of the highwall face at greater than approximately 38 degrees. The foliation orientation at several locations has the potential for plane failure. However, from observations in the field, any blocks loosened in this area will be limited in size and are anticipated to be caught on the bench below the highwall. These results are similar to previous geotechnical addendum data. Therefore, other projected failures are estimated to be limited to raveling of smaller blocks in localized areas. These localized failures are not anticipated to extend further than the bench width. 11 Morrison Quarry Annual Report 2012 P \23514\133- 23514- 13002\Deliverables\Deliv-01 -2012 Annual Report \Annual Report_2012_Geotech doc January 2013