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JCB Engineering, LLC 26 March 2004 Page 2 Sand and gravel were encountered at depths of 4 to 10 feet below ground surface and extend to the bedrock below. The sand and gravel Layers were generally poorly graded to well graded, loose to dense in relative density, contain moderate amounts of silt, and are moist to wet in-situ. The estimated maximum size of gravel and/or cobbles encountered with depth is typically less than 3-inches in maximum dimension. N values ranged from 6 to 48. Bedrock consists of interbedded siltstone and claystone bedrock. N values ranged from 50 blows for 0.2 ft to 50 blows per 0.8 ft of penetration. Groundwater was encountered at depths of 3 to 9 feet below ground surface. Terracon's test boring reports and laboratory testing data are provided as Appendix A. PROPOSED CUT SLOPE CONFIGURATION For the cut slope configuration on the east side of the pipeline, Lyman Henn understands that the proposed excavation will start at approximately 50 feet from the pipeline alignment and extend from natural ground surface at El. 4782 through the overburden at a 4:1 (horizontal:vertical) slope to a 12 ft wide horizontal bench at El. 4773. From the end of this bench, the excavation will then extend through the sand and gravel at a steep (approx. 0.25:1) slope to the bottom of the pit at El. 4753. We understand that the pit will be dewatered during the excavation. A sketch of the excavation profile is shown in Figure 2. For mining reclamation, Lyman Henn understands that the face of the excavation below the bench at El. 4773 will be backfilled with a soil liner consisting of a compacted mixture of overburden and reworked bedrock which is "keyed" into the bedrock, as shown in Figure 1. The soil liner will result in the bench at El. 4773 extending an additional 8 feet from the pipeline alignment, for a total bench width of 20 feet. We understand that the high water elevation of the reservoir will be at El. 4768, approximately 5 feet below the bench crest. SLOPE STABILITY ANALYSIS RESULTS The proposed excavation slopes were evaluated using SLOPE/W, a software developed by GEO-SLOPE International that uses limit equilibrium theory to compute the factor of safety of earth slopes. Slope stability was evaluated for the following "worst-case scenario" conditions for the slope. During mining, when the pit is excavated to its full depth and dewatered. Based on the free draining nature of the sand and gravel, we did not assume that the full height of the face of the excavation in the sand and gravel would be saturated during this excavation. During reservoir operation, immediately after rapid drawdown of the reservoir when the soil liner experiences undrained conditions. We conservatively assumed that the entire slope of the soil liner and the native soil behind it was saturated, although the proposed high water surface elevation would be 5 feet below the top of this slope.