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Spring 2017 Subsidence and Geologic Field Observations <br />South of Divide and Dry Fork Mining Areas <br />4.0 SPRING 2017 SUBSIDENCE OBSERVATIONS <br />During our spring 2017 field visit, subsidence -related tension cracks were observed above E -seam <br />Longwall Panel E6 in the SOD and Dry Fork mining areas along some drilling roads accessed by <br />USFS Road 711 (Dry Fork Road) and on MVB pads, particularly where they exist above active <br />mining activities. <br />Specific features were observed at various locations along the established traverses. Of particular <br />note were features along Traverses B -B', C -C', D -D', and E -E' (see Map 1). All of these subsidence <br />features were located above E -seam Longwall Panel E6 with the greatest number observed above <br />the most recent longwall mining activities (i.e., areas of maximum expected dynamic subsidence <br />effects). Additional details regarding the spring 2017 subsidence observations along these <br />traverses can be found in Sections 4.2, 4.3, 4.4, and 4.5 of this report. <br />The subsidence features previously -observed and discussed in earlier subsidence report were all <br />re -visited and noticeably weathered and less discernible. Also of note is that, to date, there have <br />been no subsidence -related features observed in alluvium even above active longwall mining <br />activities. <br />The following is a detailed discussion of observations associated with Traverses A -A' through F- <br />F' (see Maps 1 and 2). Map 1 shows the outline of E -seam mine workings along with surface <br />topography and other surface features, including the named traverses. Map 2 shows the same area <br />and detail as Map 1 (minus traverses) along with recently active, or potentially active, landslide <br />and rockfall areas as delineated from aerial photo research and field observations. Some of the <br />numerous photographs obtained during the spring 2017 field visit are included as figures in the <br />following text. Where these images have notable differences from previous photographs, the older <br />image has been included for comparison purposes. To reduce the overall size of this document, <br />narrative text and photographs are excluded for traverses where no noticeable change was <br />observed. <br />831-032.799 Wright Water Engineers, Inc. Page 8 <br />August 2017 <br />