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 Numerous MVB pads have been historically accessible from this traverse including E3-6, E3-12, E3-17.5, E3-21, E3-25, E4-15, E4-16, E4-17, and E4-18 over mined E -seam Longwall Panels E3 and E4. Relatively recently constructed MVB pads for E5-17 and E5-18 were added in the past year. Attempts to visit each of these pads during our fall 2015 field activities found that the MVB pads for E3-12, E3-17.5, E3-20, and E3-21 pad all been reclaimed. In the case of the MVB E3-12 pad, the road that used to traverse the edge of the pad had been moved slightly north away from the reclaimed area. Fall 2015 observations found subsidence cracks at Point I (in the cut slope east of the intersection or Traverse I -I' with Traverse H -H'). This is discussed below as Location 3. Other subsidence features observed along Traverse I -I' included locations at the MVB E4-17 pad (Location 4), along the road west of the MVB E5-17pad (Location 5) and on the MVB E5-17 pad itself (Location 6). Details associated with these observed subsidence features are discussed below. Previous reported observations (fall 2013) along this traverse included a small slump on the downslope side of the MVB pad access road above the Deer Creek valley. This slope failure was likely triggered as a result of the mining of E -seam Longwall Panel E4 beneath the area sometime after our fall 2013 field visit. This feature is approximately 800 feet south of the westernmost hairpin turn. This slump occurred in colluvial material and is more than 100 feet above the Deer Creek valley floor and approximately midway between the mined E -seam Longwall Panel E4 headgate and tailgate entries. This failure remain visible and may actually be expanding to some degree as evidenced by the earthen berm placed along the road at the upper end to warn vehicle traffic of its narrowing effect of the road at this location. E -seam overburden thickness at this location is between 450 and 500 feet. 3.12.1 Location 3 Two subsidence cracks were observed in the cut slope at Point I of Traverse I -I' during the fall 2015 field visit (see Figure 5). The longest of these observed cracks was approximately 6 feet as observed near the top of the cut. The maximum dimensions on these cracks was 4 inches wide and 12 inches deep. Some parallel cracks of much smaller length and size were also observed. E - seam overburden thickness at this location is 400 feet. 831-032.797 Wright Water Engineers, Inc. Page 13 March 2016