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<br />On April 12, 1993, an approximate 130 foot long section of the <br />portal access road was destroyed by a landslide which occurred <br />below the level of the access road. The section of road that slid <br />contained cracks and scarps but was basically intact. The slide is <br />approximately centered on the mine ventilation fan. The fractured <br />road section was simply lying seven feet below its original <br />location. The mine ventilation fan was not affected by the slide. <br />Numerous sources of water were apparent in the scarp adjacent <br />to the access road, at the approximate (-7') level of the road. On <br />April 12th the Operator mobilized personnel and equipment to <br />establish access into the mine and to contain and relieve the water <br />in the scarp. The access was established by breaking down the <br />scarp on each end of the road. The road now ramps down into the <br />area that slid, then ramps back up to the original level of the <br />mine portal access road. A french drain was placed adjacent to the <br />• scarp in the failure surface of the slide in a position expected to <br />relieve and intercept any groundwater entering the failure surface. <br />PREVIOUS INVESTIGATIONS <br />In the spring of 1982 Rocky Mountain Geotechnical (RMG) <br />conducted a slope stability investigation which produced a report <br />titled, Stability Analysis of Portal and Access Road Areas Bear <br />Mine No. 3 Somerset, Colorado. The report provided the results of <br />the investigation and a computer assisted slope stability analysis <br />of the existing slope conditions in the portal areas and access <br />road. <br />Their results indicated that the existing stability in the <br />area of the slide, which occurred April 12, 1993, was marginal at <br />best with factors of safety of 0.809 using residual strength <br />parameters for the colluvium and 1.255 using the optimistic peak <br />strength parameters for the colluvium. Obviously the true factors <br />• of safety present on the site, at the time of that investigation, <br />21-3 <br />