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Memorandum <br />Rock Logic Consulting <br />Rock Logic PO Box 544 • Cedaredge, CO 81413 <br />Consulting LLC Phone: (435) 851 -9044 • rocklogicconsulting @gmail.com <br />Brad Lindsay • Consulting Geologist <br />Date: 7 June 2012 <br />To: Jim Abshire <br />Bill Bear <br />John Zutman <br />From: Brad Lindsay <br />Subject: Spring 2012 Subsidence Crack Mapping <br />Field Survey <br />A thorough field survey above the B -11 longwall area was conducted in May 2012. The mined B -11 <br />panel runs north -south west of terror creek. Areas of both mildly sloping terrain and steep <br />topography overlie the panel. Traverses over most of the panel were hiked to observe visual evidence <br />of subsidence. Thick brush, cliffs, and steep slopes exist in the area. A GPS unit was utilized in <br />track mode to record the path of all traverses and locations of cracks observed. Each new crack was <br />photographed and the orientation, length, width, and vertical displacement were measured. <br />Observations <br />Twenty seven individual cracks were observed covering almost the entire B -11 panel. Many, but not <br />all the cracks roughly follow the surface topography. Some cracks near the edge of the B -10 panel <br />appear to correlate with cracks observed last fall. Cracks over the B -10 panel still exist, but are <br />beginning to heal. <br />Files <br />Crack measurements and field notes are recorded in an Excel file (Subsidence Crack Mapping Spring <br />12.xls). The AutoCAD map ( Subsidence - Crack- May12- source.dwg) was updated with the track <br />surveyed and lengths, orientations, and locations of new cracks observed. Digital photos of <br />the cracks are attached. <br />