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Fall 2008 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />• 5.5.4 Location 6 (Location 6 of the Spring 2008 Field Visit) <br />Cracks were initially observed at this location in 2006 in graded material for NIDWs 19-01, 19- <br />02, and 19-03 and above the northeastern edge of mined Longwall Panel 19. The drill site is <br />constructed primarily in soil and colluvium derived tram the Wasatch Formation. }lased on their <br />location, these cracks were within the area of maximum tensile strain and about 2,250 feet above <br />the 13-seam. Observations made during spring and fall 2008 (Figure 16) reveal that the locations <br />of the cracks are no longer discernable due to additional healing and grading of the site. <br />At the time of- their original observation. these particular cracks were thought to have been <br />related equally to differential settlement of the graded material and subsidence. Giycn the <br />completion of mining beneath this area and the regrading of the drill pad, it appears the actual <br />explanation \yill never be fully known. <br /> <br />;M _ ? . rte'-?? <br />Figure 16. Fall 2008 view of what used to be east-trending cracks in graded colluvium, on the <br />northern edge of MDWs 19-01, 19-02, and 19-03. <br />5.5.5 Location 7 (Location 7 of the Spring 2008 Field Visit) <br />\s previously noted, Traverse E-F.' Nyas extended approximately 800 feet of Location 6 to the <br />• drill pad for `,If) Ws 18-39, 18-40, 18-41. and 18-43 as ofOUr spring 2008 field visit. This %IDW <br />pad. designated as Location 7, represents the northernmost location on the traverse. Location 7 is <br />831-032.790 Wright Water Engineers, Inc. Page 31 <br />December 2008