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TECHNOLOGIES INC <br />• <br />September 9, 1997 <br />Mr. Jim Stover <br />J.E. Stover & Associates <br />2768 Compass Drive, Suite 101 <br />Grand Junction, Colorado 81428 <br />96 South Zuni Sweet <br />Denver, Colorado 80223-1292 <br />Telephone: (303)744-7105 <br />Feceim0e: (303) 744-0270 <br />Subject: Observation of Portal Slide and Portal Bench Slope Stability, Bowie No. 2 Mine, <br />Bowie, Colorado <br />Project No. 5003700102 <br />Dear Mr. Stover: <br />At your request, the undersigned visited the subject site on August 20, 1997 to observe the <br />conditions of a slide which occurred on the cut slope above ttte portal entrance. <br />Present Conditions: At the time of our site observation, the portal bench had been constructed <br />and the conttactor was in the process of constructing the initial portal entrances. The toe of the <br />cut slope at the base of the portal entrances had been cut back alto the slope leaving an <br />approximately 40-foot nearly vertical slope. Once the portal entrance can be established, multi- <br />plate will be placed extending back to the portal entrance and backlill will be constructed above <br />the multi-plate to re-establish the slope. <br />We understand that a portion of the slope above the western-most portal failed on Sunday, <br />August 18, 1997. When we arrived at [he site we observed a slide that was about 125 feet wide <br />and extended from the portal to about three quarters of the slope height. The remainder of tl)e <br />cut slope above the middle and eastern-most portals was stable witl7 fairly competent material <br />exposed on the nearly vertical face. Some minor sloughing had occurred above the eastern-most <br />portal area. <br />The slide that occurred above the western-most portal appears to be surficial and the result of <br />the undercutting of the slope toe. The soils exposed above this portal were visibly weaker than <br />along the remainder of ttre cut consisting of pockets of fat clay with evidence of coal bum <br />debris. There was no evidence of seepage along this portion of the cut slope; however, seepage <br />was observed further to the west adjacent to the slide zone. TI7is is near the area of our Boring <br />18 which encountered groundwater at about elevation 6993. It does not appear that the seepage <br />impacted [he slide. <br />The undersigned observed the area above the west and north cut slopes. No evidence of <br />potential slope instability was observed. <br />• <br />Austin Research Engineers Chen-Northern Empire Soils Investigations <br />Kansas City Testing Southwestern Laboratories .Twin City Testing <br />a e <br />mod' -rte-O <br />