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5.8 Traverse K4 -K4' <br />Spring 2011 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />Traverse K4 -K4' originates along the south side of Dry Fork Road and travels south and then <br />west to drill pads for MDW E2 -13 and E2 -9 over mined E -seam Longwall Panel E2 (Map 2). <br />Thick soil and colluvium derived primarily from the Wasatch Formation are evident along this <br />traverse with overburden depths to the E -seam between 550 and 650 feet. Baseline conditions <br />were observed along this route during the fall 2010 field visit. Mining beneath this area occurred <br />during May 2011 (approximately 4 to 6 weeks prior to the spring 2011 field visit). <br />Subsidence - related cracks were observed at three specific locations along this traverse; on drill <br />pad MDW E2 -9 (Location 6), on the roadway leading onto the MDW E2 -9 pad (Location 7), and <br />on the hairpin corner above the MDW E2 -13 drill pad (Location 8). All three locations are above <br />the mined E -seam Longwall Panel E2. <br />5.8.1 Location 6 <br />Location 6 is the numerous subsidence cracks observed on the MDW E2 -9 drill pad. Longwall <br />mining occurred beneath this well pad approximately three weeks prior to our site visit. This pad <br />is approximately 300 feet from the tailgate entries of the underlying mined E -seam Longwall <br />Panel E2 in an area with an overburden thickness of approximately 650 feet. <br />The longest observed crack was a continuous series that ran approximately 90 feet and extended <br />into the cut slope above the well pad (Figures 25 and 26). Many of these cracks trended between <br />N10 °E and N5 °W. This orientation is incongruous with the differential settlement cracks <br />parallel to the fill slopes as previously observed on this pad. These differential settlement cracks <br />were parallel with the fill slopes but had sharper edges and greater width and depth dimensions <br />than before. It was clear that these cracks had been influenced by the recent mining beneath the <br />area. The maximum observed width and depth of the cracks was 1 inch and 4 inches, <br />respectively. <br />831 - 032.793 <br />September 2011 <br />Wright Water Engineers, Inc. Page 33 <br />