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1 <br />Memorandum to Henry Barbe <br />September 27, 2000 <br />Page 12 <br /> <br /> <br /> <br /> <br />1 <br /> <br /> <br /> <br /> <br />Figure 4 <br />' Northward view ojsubsidence crarks forming small graben in sandstone outcrop located above <br />the approximate midpoint ojmined-out longwa(! panel 13. Trend ojcracks is N10E to Nom. <br />' Location 18. Located at Location 6 of September 1999. Point was re-occupied to observe <br />the changes that have occurred in one year. The point is located at an <br />outcrop of sandstone and thin, sandy soil and colluvium and is located 1,200 <br />' feet above the B-seam, where longwall mining has been completed. <br />• Tension cracks are narrower and less extensive than last year. Many cracks in the <br />' bedrock have apparently closed, now that tension is relieved by uniform longwall <br />extraction. Only about 10 percent of the cracks observed last year still exist. <br />' • The compression features observed last year are not visible now (see WWE report of <br />October 7, 1999, for more details). <br />' • No subsidence cracks or other subsidence features were observed during the ATV <br />traverse along the drill road from Location 16 to Location 18. Overburden thickness to <br />B-seam along traverse from Location 16 to Location 18 ranges from 1,200 to 1,300 feet. <br />' Wright Water Engineers, Inc., 2490 W. 26'" Avenue, Ste. 100A, Denver, CO 80211 <br />Tel. 303/480-1700; Fax. 303/480-1020, e-mail:krwright@wrighlwater.com <br />1 <br />