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Subsidence and Geologic Field Observations <br />Apache Rocks and Box Canyon Mining Areas <br />July 12-15, 2004 <br />1. Cracks as much as 1.5 inches wide locally occur roughly parallel to the ridgeline. The <br />cracks, which occur in weathered clays of the Wasatch Formation, may have primary <br />and secondary causal components: the primary cause appears to be gravity-induced <br />lateral movement; the secondary is likely caused by desiccation. <br />2. The cracks are located where the ridge becomes very narrow in two places, about 500 <br />feet long, above parts of un-mined longwall panels 19 and 20 and un-mined longwall <br />pane121. <br />4.2 Subsidence Observations and Evaluations for July 13, 2004 <br />4.2.1 Traverse G-G' <br />This vehicle traverse begins at fork in drill road north of Twin Ponds and ends at methane <br />drainage well site MDW-17-O5. The methane drainage well site and access road to it were being <br />reclaimed during the visit. <br />• Traversed above mined longwall panels 15, 16, and the northern edge of mined longwall <br />panel l7. <br />• Colluvium, soil (which is locally a few feet thick), and local weathered bedrock were <br />encountered in the traverse. <br />• Overburden depth to the B Seam ranges from 1,500 to 1,650 feet. <br />• No subsidence features were observed. <br />4.2.2 Traverse H-H' <br />This vehicle traverse begins at the fork in drill roads above mined longwall panel 16 and ends at <br />methane drainage well 17-02. <br />831-032.640 Wright Water Engineers, Inc. Page 19 <br />September 2004 <br />