REP05386 - Laserfiche WebLink

Home Browse Search

B. South End, North End, and West Side ' The overall slope in the south end appears stable. There are localized areas of instability on individual benches due to "poor" rock mass conditions. Localized areas ' of instability were observed in temporary slopes and these conditions will continue to be observed during further development in this area. Rock mass properties significantly improve with depth, due to higher strength parent rock, less weathered and more massive than the rock mass above, which is composed of low strength rock material ' with weathered and slick joint surfaces. The overall slope on the west side appears stable. Localized instabilities are infrequent ' and consist of relatively small loose blocks and wedges, generally less than 10 feet in length. These instabilities are as expected for the highwall and only cause localized operational inconveniences. A portion a constructed fill for the access road to the pit ' bottom was observed to have failed as it became saturated due to the filling of the reservoir. Although this may create operation problems for the reservoir, it is not expected to adversely impact the stability of the rock slopes or pit walls. The overall slope on the north end appears stable. Localized instabilities are infrequent and consist of relatively small loose blocks and wedges, generally less than 10 feet in length. These instabilities are as expected for the highwall and only cause localized operational inconveniences. 5.03 North Quarry The highwalls and benches are aligned curvilinear bearing approximately 000 to 080 azimuth as the pit extends to the east. The rock type is primarily granite gneiss with mafic and felsic intrusions (felsite dikes and pegmatites). For Bench 1, the primary joint set coincides with foliation of the rock mass. In general, the foliation dips in a southwest direction. Foliation orientation has local variations due to several sets of localized anticline/syncline structural features in [he rock mass. The primary joint set is perpendicular to sub-perpendicular on the northern side dipping into the mining face. Dip angle varies from approximately 15° to 45°. Joint set information is provided in Table I. Spacing of joints in the primary joint set typically ranges from 0.5 ft to 2 fr. Joint surfaces are typically tight and appeaz slightly to moderately weathered. Joints are very continuous in certain locations, and discontinuous in other locations. One dominant secondary joint set is present. This near vertical joint set strikes in a northeast direction. Joint set information is provided in Table I. Spacing of joints in the secondary joint set typically ranges from 1 to 5 feet. Joint surfaces are typically tight and appeaz slightly weathered. Joints are both continuous and discontinuous. The overall slope appears stable. Localized instabilities are limited to single benches and are evidenced by relatively small block and wedge shaped slip surfaces, generally less than 10 feet in length. These slip surfaces are as expected for the highwall and cause only localized operational inconveniences.