2008-03-05_REVISION - M1997054 (32)

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4.03 Phase II Phase H will continue from drainage 2 east to the northeast corner of the mining limits and south to drainage 3. Benches and highwalls in Phase II will be developed beginning at the northern and eastern mining limits and proceed inward and down to the platform elevation 5800 ft established in phase I. The area previously opened in Phase I will be incorporated into Phase II by further excavation to elevation 5700 ft. Final benches and highwalls above elevation 5800 ft in Phase I and some in Phase II will begin to be reclaimed by backfilling the benches to reduce visual impacts. Phase II bench and highwall configurations are shown in figure D-1, Mining Plan. 4.04 Phase III Phase III begins development of benches and highwalls from the south side of drainage 3 to the southern corner of the mining limits and ties into Phase I on the southeastern side of drainage 2. Again, the benches and highwalls will be developed from the outer edges of the mining limits inward and down. The area previously opened in Phase II will be incorporated into Phase III by further excavation to platform elevation 5750 ft. Phase I will remain at elevation 5700. Final benches and highwalls above elevation 5800 ft in Phase H and some in Phase III will begin to be backfilled to reduce visual impacts. Phase III bench and highwall configurations are shown in figure D-1, Mining Plan. 4.05 Phase IV Phase IV is the continuation of excavation and development of benches and highwalls to the final build-out to a bottom elevation of 5300 ft. Phase IV also encompasses the continuation of backfilling of select previously excavated benches. Final benches and highwalls above elevation 5800 ft in previous phases will begin to be backfilled to reduce visual impacts. Phase IV final build-out bench and highwall configurations are shown in figure D-l, Mining Plan. 4.06 Discussion The quarry will be developed to the maximum volume recoverable within the footprint of the limits of mining. Mining will occur within the limits of mining. The maximum recoverable volume is dependent on the final cut slope angles within the mine, which are dependent on the structure and behavior of the rock mass during excavation. The mining plans shown in Figures D-1 through D-4 show the most aggressive maximum build-out configurations which are likely to be achieved if the rock mass properties are sufficient to support the benches and highwalls as shown. These anticipated maximum build-out conditions are based on information gathered during a visit to the proposed quarry site and from a geotechnical investigation performed by J.A. Cesare and Associates, Inc. Phase IA will be used as a trial or demonstration phase in which bench and highwall performance will be evaluated in various orientations. Observations of Phase IA will lead to recommendations for bench and highwall configurations in Phase IB with continued observations of bench and highwall performance as the quarry is developed. A. Observational Method Based on presently available information, it is not practical to model the rock mass in sufficient detail to predetermine absolute final slope configurations. Therefore, the "observational method" approach to determining stability of final cut slopes will be ` -employed. The observational method is a rigorous series of interactive steps of excavating rock, observing the condition of the rock mass and behavior of rock slopes, \\Secver0l\common\PROJECTS\106052-000 Parkdale Mine Plan\R. Records and Correspondence\R.11 Reports\Permit_1_24_08.doc