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Spring 2008 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />Wasatch Formation. Based on their location, these cracks were within the area of maxurlunl <br />Icnsile strain and a B-seam overburden depth of ahout 2?50 feet. <br />Observations IMILIC durin- spring, 2008 (Fi"ore 20) revealed that the locations ()I' the cracks arc <br />no lon-er dlseclrnahle due to additional healing and `1radin° ol'the site. <br />These particular cracks were thought to he related to either differential settlement of' tile i_,radcd <br />nultcrial and/or to suhsidcnce. It was previously estinut(cd that the probcthility of the cracks <br />heinc settlement related versus suhsidcnce related was about 50 I)crccnt. At this time it is <br />unlikely that the actual explanation will he determined. <br />• <br />Figure 20. Spring 2008 view of what used to be east-trending cracks in graded <br />colluvium, on the northern edge of MDWs 19-01, 19-02, and 19-03. <br />5.5.4 Location 7 <br />"rrctverse F.-F.' extended approximately 800 feet fl-u-ther north on West Flatiron than any previous <br />traverses to observe a drill pad I'or new ?11)Ws 18-31). 18-40, 1<8-41. and 18-43). This pad is <br />located in uraded material above the Lonmwall Panel 19 taiknite. "rhe overhurdcn depth to for 13- <br />scam in this area is about 2,200 feet. The drill site is constructed prinlarllV In soil and C011LIVIUn1 <br />derived Front the \Va,atch Formation. ;Vii suhsiclence related feauuVs were noted :u this 10C,11ion. <br />• 831-032.790 Wright Water Engineers, Inc. Page 31 <br />August 2008