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t _• • MCC must analyze the failure in order to develop an acceptable methodology for rehabilitation and stabilization of the substation cutslope. Back calculation of the exact failed configuration should provide more accurate material strength parameters for use in the development of remedial treatments and final reclaimed treatments for the effected cutslope. Lower Sylvester Gulch Access Road - Slope Distortion Pursuant to my suggestion, MCC installed two slot-track tiltmeters in combination with piezometer installations immediately upslope from the lower Sylvester Gulch Road. The first of these installations has been in place for a month. Offsets have been documented at depths of approximately 15 and 30 feet, roughly corresponding with the existing access road. The approved plan for the widening of the lower Sylvester Gulch road included the excavation of a relatively high cutslope at the location of this tilt-meter. The evidence suggest to me that excavation of the planned cutslope will initiate an accelerated slope failure at this location. Appropriate methodology exists with which to reinforce this slope prior to excavation of material which currently buttresses the slope. Whether or not these techniques are adequate to prevent accelerated failure should be analyzed in detail. As an alternative design consideration could be focused upon the development of traffic signal controlled single lane access road. The second slot-track tiltmeter was installed the day before my tour of the site. The initial orientation data had been collected, but no comparative subsequent observations had been completed. Based upon my observations of the active landsliding which has characterized this location I anticipate movement similar to that observed at the first installation. [Nine iterative sensitivity slope stability analyses were conducted for this site. Safety factor results varied from 0.940 to 1.5 It appears the 0.940 may have been accurate.] cutslope South of the Ventilation Sha ti; nch - Stability Concern The slope southwest of the main ventilation shafts was being grubbed and excavated. Mr reconnaissance examination of the large caliber conifers and aspen occupying the slope discerned a high frequency of curved (pistol grip) trunks, suggesting active soil movement. I suspect that this slope may experience soil and shallow weathered bedrock veneer failures analogousy~.~~o the failure occurring on the substation cutslope. This slope Fua~ benefit from the installation of tiebacks or piling to prevent failure prior to the installation and backfilling of the surface diversion culvert along it's toe. Shaft #3 Collar Elevation Change - cutslope Concerns e Mr. Mende accompanied me to the bench constructed to serve as the collar for the 10 foot diameter ventilation bore #3. The pioneer bore determined that the bedrock surface is approximately 25 feet