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"Observational Method" will be used to determine slope stability and cut slope design and construction. Refer to Amendments Nos. 3 and 4 for detailed descriptions of the Observational Method and existing implementation steps for highwall and bench configurations within the Morrison Quarry that will continue unchanged by this Amendment. 4-03. QUARRY DEVELOPMENT NARRATIVE The maximum final buildout configuration for the Morrison Quarry is presented in plan view in Figure D-4, Exhibit D - Phase N (Final) Mining Plan Map. Intermediate phases have been included in the proposed mine development to address reclamation of the mine, handling of surface water, and other operational considerations. Typical highwall and bench configurations were presented in Amendment No. 4 as Figure D-9, Typical Highwall and Bench Cross-Section. The standazd design configuration for the quarry remains unchanged and consists of maximum 80 ft highwalls and minimum 40 ft benches. Several exceptions to the standard are noted including: 1) the previous slope remediation area at the East Highwall of the Central Quarry, 2) flatter configurations along upper portions of western exposures to reduce visual impacts, and 3) other areas as necessary to address slope stability concerns in areas of lower anticipated quality rock, unusually high rock slopes, and key design areas near the proposed reservoir sites. Highwalls will generally be developed in two 40 ft high levels which correspond to the typical drill length for shot holes. Benches are designed to be 40 ft, 60 ft, or 80 ft wide depending on requirements for reclamation and stability. The upper benches on westem quarry walls, which may be highly visible to viewers outside the quarry from the east and southeast, are designed to be either 40 ft x 60 ft (highwall x bench} or 80 ft x 80 ft to accommodate a larger wedge of soil for reclamation, revegetation, and reduced visual impact. The limits of application of this less aggressive configuration vary depending on location to bring visual impact mitigation down to elevations generally matching natural visual barriers (ridges) east of the quarry. This configuration will result in a relatively small visual impact upon completion of the reclamation process. Below these upper benches, [he maximum development plan is for 80 h highwalls and 40 ft benches. Shallower slope angles than shown may be required based on future geotechnical evaluations. Rock will be removed by conventional blasting, loading with an excavator and/or a loader, and transportation with 50 or 85 ton trucks for the majority of the quarry. For some areas of the quarry, especially the exveme high and low areas, it is likely that truck haulage will not be practical due to the potentially steep and/or long grades for haul roads. Given these conditions, lower quarry development may utilize in-pit crushers and conveyors to assist in transporting crushed product to the plant area for final processing. The following pazagraphs summarize the nature and expected duration of each mining phase. The durations noted are based on reserves estimates and production rates considered CONFIDENTIAL by CAMAS. If this G ~PROIECfSI?030POpTlFJCfUMFN003.TXT IV - 4