Laserfiche WebLink
<br />of instability were observed and are expected to be of continued concern during further <br />development in this area. <br />Based on these conditions and on comparisons with baseline conditions for the analyses, <br />slopes at the east end of the North Quarry are presently being excavated at an inclination <br />of approximately 1H:1V or flatter. This classification and excavation geometry may <br />change as additional or different rock is exposed in this area and as additional observations <br />are made. <br />A[ present, work in the North Quarry is not at the ultimate limit of the planned excavation, <br />therefore, precision blasting techniques are not presently being used. When excavation <br />occurs at the proposed quarry walls and if the slopes are to be excavated with an overall <br />inclination exceeding 1H:1V, precision blasting techniques are planned. <br />SUMMARY AND CONCLUSIONS <br />Development of Cooley's Morrison Quarry is continuing in general accordance with the <br />approved Mine Plan. Mining is continuing at the south end and east side of the Central Quarry <br />and the east end of the North Quarry in accordance with the Observational Iviethod presented <br />and approved in the permit. <br />Present excavations do not generally reflect [he ultimate, final quarry walls. Excavation of the <br />East Highwall for [he Central Quarry is progressing as planned with ground conditions similar <br />to those assumed for the baseline stability condition. However, the width of the fourth bench <br />will likely be decreased slightly so [hat the remaining benches and highwalls will better fit the <br />geometry of the actual slope. A network of survey monuments for monitoring potential slope <br />movement will be installed. <br />Due to a relatively weak parent rock material at the south end for the Central Quarry, benches <br />and highwalls are presently being excavated no steeper than 1H:1V. <br />At the east end of the North Quarry, benches and highwalls are presently being excavated no <br />steeper than 1H:1V. This slope configuration is due to the weak rock near the ground surface <br />and adverse joint orientation. Present excavations do not reflect [he ultimate slope <br />configuration for the quarry. <br />Localized adverse jointing of rock in benches and highwalls has resulted in the isolated <br />occurrence of blocks and wedges dislocating from the highwalls at the outboard edges of <br />benches. This condition will probably continue to occur and will be monitored and evaluated <br />on a case-by-case basis. The methods of mine development, blasting, excavation, and <br />evaluation used to date have been effective in controlling slope stability within expected <br />parameters. <br />G:LO'_OO~R09i00.t00 <br />