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Rock Logic Consulting <br />O ~OCI{ LOg1C PO Box 544 • Cedaredge, CO 81413 <br />consulting L,LC Phone: (435) 851-9044 • rocklogicconsulting@gmail.com <br />Brad Lindsay • Consulting Geologist <br />Memorandum <br />Date: 2 August 2007 <br />To: Collin Stewart <br /> Ry Stone <br /> Bill Bear <br />From: Brad Lindsay <br />Subject: Spring 2007 Subsidence Crack Mapping <br />Field Survey <br />A field survey of the roadways above the B 1, B2, and B3 longwall areas was conducted on <br />May 31, 2007. Roadways in these areas were walked or driven over slowly to observe <br />subsidence cracks. A detailed field survey was conducted above the B4, and BS longwall <br />areas that same day. Areas were hiked between and adjacent to Freeman Gulch Road and the <br />main road that runs along the top of the ridge. Each new crack was photographed and the <br />• orientation, length, width, and vertical displacement were measured. <br />Observations <br />Cracks identified in the 2004 through 2006 surveys have healed or continue to heal. Many of <br />these cracks are no longer visible. Very few cracks were observed during this field survey. <br />One series of cracks was observed on the GVB-S-A drill pad. These cracks appear to be due <br />to slumping of fill material from the pad construction. The same cracking may have occurred <br />without any mining. The other cracks were small and only observed in sandstone bedrock <br />southeast of the upper lay-down area. Most of the B-4 and B-5 mining areas lay below <br />Freeman Gulch. Much of this area is covered with thick vegetation making it difficult to see <br />any cracks that may exist. <br />Files <br />Crack measurements and field notes are recorded in an Excel file (Subsidence Crack <br />Mapping.xls). The AutoCAD map (Subsidence-Crack-May07-source.dwg) was updated <br />with the lengths, orientations, and locations of new cracks observed and areas surveyed. <br />Digital photos of the cracks are attached. <br />M1-1 <br />