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Subsidence Field Observations <br />West Elk Mine <br />July 22-24, 2003 <br />• Traversed above the approximate middle of mined longwall Panel 14 and northward to the <br />south edge of projected longwall Pane] 24. <br />• Massive sandstones of the upper part of the Ohio Creek Formation, in addition to colluvium <br />and soil, were encountered in the traverse. <br />• Overburden depth to the B-Seam ranges from 1,625 to 2,050 feet. <br />Location 1: <br />Subsidence cracks were observed in [he massive sandstones of the Ohio Creek Member of the <br />Mesaverde Formation. <br />• One crack (Figure 1), which is as much as 0.5 inch wide and trends N60°W, transects the <br />upper two massive sandstones-a vertical distance of about 75 feet. Overburden depth to the <br />B-Seam is about 1,800 feet. <br />• The cracks are located near [he midpoint, both transversely and longitudinally, of mined-out <br />longwall Panel 14. <br />• Other subsidence cracks, or pre-existing fractures affected by subsidence, were observed a <br />few hundred feet west of Location 1 (Figure 2). This area probably was already fractured, but <br />was further disturbed by longwall mining below. <br />831.032.610 Wright Water Engineers, Inc. Page 8 <br />September 2003 <br />