2016-04-19_REPORT - C1980007 (6)

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Fall 2015 Subsidence and Geologic Field Observations South of Divide and Dry Fork Mininq Areas 2.0 SUMMARY OF FALL 2015 FIELD STUDIES On October 8 and 9, 2015, WWE performed subsidence and geologic field investigations of the SOD and Dry Fork mining areas for MCC as the second part of 2015 field activities. Based on field observations to date, the overall effects of longwall mining have been less than initially projected. Twenty years of experience (1996 to 2015 inclusive) indicate that subsidence features (cracks and bulges) are most visible on roads and trails, where the ground is more compact and free of vegetation. These areas (or traverses) are targeted for specific observations either on foot or using a 4 -wheel drive vehicle. In addition, photographic comparisons are routinely made to evaluate and document changes between observations (using regularly visited photographic observation points) and to record their condition for future reference (Maps 1 and 2). Subsidence -related tension cracks were observed during our fall 2015 field visit to the SOD and Dry Fork mining areas particularly where they exist above active mining locations. Subsidence - related tension cracks observed in previous site visits were noticeably weathered and less discernible. These features are discussed in Section 3.0. Longwall mining in the SOD and Dry Fork mining areas was initiated at the east end of E -seam Longwall Panel E1 in December 2008. At the time of our fall 2015 field visit, mining was complete on E -seam Longwall Panels E1, E2, E3, E4, and E5 and had recently been initiated on the east end of E -seam Longwall Panel E6. Subsidence -related features were observed at the surface along Traverses F -F', H -H', I -I', and JJ. Additional details regarding the observed subsidence features can be found in Sections 3.11, 3.12, and 3.15 of this report. 831-032.797 Wright Water Engineers, Inc. Page 3 March 2016