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Subsidence Field Observations <br />West Elk Mine <br />August 27-29, 2002 <br />4.3.1 Traverse K-K' <br />This traverse covers the trail down Deep Creek from a jeep road in the upper part to the mud hole <br />in the trail where it crosses the first drainage south of West Flatiron. <br />• Traverse is first located above an azea with no projected longwall mining panels for about <br />6,000 ft, thence above un-mined projected longwall Panels 17 and 16, thence above mined- <br />out longwall Panel 15 in overburden ranging from 1,100 to 1,300 ft thick. <br />• Conditions on the traverse look much the same as last year on August 28, 2001. <br />• Soil and alluvium/colluvium along traverse, which consist of gravel and boulders from the <br />Tertiary intrusive rocks of Mt. Gunnison contain some clay from the Wasatch Formation. <br />• The Wasatch clay content decreases downstream (northward); the boulders also decrease in <br />size from about 4 ft in long dimension at the beginning of traverse, to a foot or so. <br />• No subsidence features (cracks or bulges) were observed within the azea of mining influence <br />of longwal] Panel 15. The thick alluvium and colluvium likely can yield without rupturing <br />during longwall mining. <br />Location 1 I: <br />Landslide complex located west of the mouth of Horse Gulch and near the northern abutment of <br />Minnesota Reservoir (Figure 15). <br />• Landslide is located 1,000 ft from the southern boundary of longwall Panel 13-A, and <br />therefore is located outside of the azea of any mining influence (using the most conservative <br />angle of 45°). Therefore, the landslide is completely related to natural processes. <br />' 831-032.570 <br />December 2002 <br />Wright Water Engineers, Inc. <br />Page 19 <br />