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Rock Logic Consulting <br />Rock Logic PO Box 544 • Cedaredge, CO 81413 <br />is Consulting LLC Phone: (435) 851-9044 • rocklogicconsulting@gmail.com <br />Brad Lindsay* Consulting Geologist <br />Memorandum <br />Date: 25 November 2008 <br />To: Jim Abshire <br /> Ry Stone <br /> Bill Bear <br />From: Brad Lindsay <br />Subject: Fall 2008 Subsidence Crack Mapping <br />Field Survey <br />A detailed field survey above the 136 and B7 longwall areas was conducted. Roadways in these areas <br />were walked or driven over slowly to observe subsidence cracks. Areas between and around <br />roadways were hiked. A cursory field survey along roadways above the 138, B9, B10, and B11 <br />longwall areas was conducted. The surveys were completed in November 2008. Each new crack <br />was photographed and the orientation, length, width, and vertical displacement were measured. <br />Observations <br />is The area over the 137 longwall was checked extensively. Surprisingly few cracks were observed. <br />Most of the cracks observed were small and expressed only in bedrock. In previous surveys cracks <br />were observed in the soil as well as bedrock. No cracks were observed above the B8 - BI 1 longwall <br />panels. The attached map outlines areas that were walked or driven. <br />Files <br />Crack measurements and field notes are recorded in an Excel file (Subsidence Crack Mapping Fall <br />08.xls). The AutoCAD map (Subsidence-Crack-NOV08-source.dwg) was updated with the lengths, <br />orientations, and locations of new cracks observed and areas surveyed. Digital photos are attached. <br />r? <br />LJ