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<br /> <br /> <br /> <br /> <br />Memorandum <br />Date: 09 Dec 2015 <br />To: Jim Abshire <br /> Bill Bear <br /> Art Etter <br />From: Brad Lindsay <br />Subject: Fall 2015 Subsidence Crack Mapping <br /> <br /> <br />Field Survey <br />A field survey above the B-17 longwall area was conducted on November 20th 2015. The B-17 panel <br />runs in an east west direction west of Terror Creek and south of West Fork Terror Creek. Much of <br />the surface topography is steep facing north, south, and east. Traverses over the panel were hiked to <br />observe visual evidence of subsidence. Thick oak brush covers most of the area. An aspen stand lies <br />over the west end of the panel. Snow covered all the ground except south facing slopes and some of <br />the flats. This made it difficult to identify small cracks in those areas. 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 measured. Only <br />one crack was observed in this investigation. <br /> <br />Observations <br />Areas with snow were traveled in a loose grid to look for large cracks. No cracks were observed in <br />snow covered areas. Areas with patchy or no snow were traveled thoroughly. One small crack was <br />identified. It is 1 inch wide and 20 feet long. <br /> <br />Files <br />Crack measurements and field notes are recorded in an Excel file (Subsidence Crack Mapping Fall <br />15.xls). The AutoCAD map (Subsidence-Crack-Nov15-source.dwg) was updated with the GPS track. <br />Digital photos of the crack and area are attached. <br />Rock Logic Consulting <br />PO Box 544 • Cedaredge, CO 81413 <br />Phone: (435) 851-9044 • rocklogicconsulting@gmail.com <br /> <br />Brad Lindsay • Consulting Geologist