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' approximately parallel with the slope, and dipping approximately perpendicular <br /> to and out of(south) the north highwall slope. In response to such occurrences <br /> with a south to north mining , <br /> operation (south-facing slopes with south dipping <br /> daylighting joints), CAMAS modified mining in the North Quarry to an east to <br /> west operation to create interim active mining slopes that are more east-facing <br /> and;therefore, more stable with respect to the prevailing south dipping joints in <br /> ' this area. This is shown to be well developed with stable highwalls in the <br /> attached topographic map depicting 1997 conditions. <br /> ' D. Based on the conditions observed in 1995 and 1996, the shallow rock mass in <br /> the northeast part of the North Quarry was tentatively classified as "poor" in <br /> terms of the previously-established baseline conditions. This classification was <br /> based primarily on the adverse orientation of the primary joint set along foliation <br /> which dips out of the slope (daylights). Additionally, the rock mass within the <br /> weathered zone was classified as "poor" based primarily on the low unconfined <br /> compressive strength of the shallow parent rock material. <br /> Further development of the North Quarry during 1997 was generally below the <br /> shallow weathered zone in better quality rock. This combined with the change <br /> ' from south to north, to east to west North Quarry development to create more <br /> favorable interim highwall orientations with respect to the primary foliation joint <br /> ' set results in "competent" rock mass conditions for the work completed during <br /> 1997. <br /> Despite these more favorable baseline conditions, slopes in the North Quarry are <br /> presently being excavated at an inclination of approximately Ili:IV or flatter, <br /> generally with only 40 ft highwalls. CAMAS is developing lower highwalls than <br /> the default 80 ft highwail by 80 ft bench. Ili:IV configuration to provide <br /> ,generally improved safety conditions in the mine and allow observation of lower <br /> highwail exposures before deciding to excavate higher ones, although not <br /> required to do so. <br /> E. At present, work in the North Quarry is not at the ultimate limit of the planned <br /> excavation, therefore, precision blasting techniques are not presently being used. <br /> ' When excavation occurs at the proposed quarry walls and if the slopes are to be <br /> excavated with an overall inclination exceeding IH:IV, precision blasting <br /> techniques are planned. <br /> ' 12 G,TROJ ECTS\-10200u102\97ANNRPr.W PF <br />