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Spring 2018 Subsidence and Geologic Field Observations <br />South of Divide and Dry Fork Mining Areas <br />4.0 SPRING 2018 SUBSIDENCE OBSERVATIONS <br />During our spring 2018 field visit, subsidence -related tension cracks were observed above E -seam <br />Longwall Panels E6 and E7 in the SOD and Dry Fork mining areas along some drilling roads <br />accessed by USFS Road 711 (Dry Fork Road) and on MVB pads, particularly where they exist <br />above active mining activities. <br />Subsidence features were observed at various locations along the established traverses. The most <br />notable subsidence features were located west of MVB E6-10 above mined E -seam Longwall <br />Panel E6 and between MVB E7-7 and MVB E7-10 (i.e., areas of maximum expected dynamic <br />subsidence effects). Details associated with the spring 2018 observation of subsidence features <br />can be found in Sections 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, to date, there have been no <br />subsidence -related features observed in alluvium even above active longwall mining 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. Also on Map <br />1, note that a designation similar to E6-1/2/3 indicates one MVB pad containing three drill holes <br />with the surface and termination point of each drill hole shown by a small and large filled green <br />circle, respectively, that are connected by a green line. <br />Some of the numerous photographs obtained during the spring 2018 field visit are included as <br />figures in the following text. Where these images have notable differences from previous <br />photographs, the older image has been included for comparison purposes. To reduce the overall <br />size of this document, narrative text and photographs are excluded for traverses where no <br />noticeable change was observed. <br />831-032.900 Wright Water Engineers, Inc. Page 8 <br />August 2018 <br />