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zones of weakness, however, because orientations are nearly horizontal, they would not be <br />considered a condition of potential failure by themselves during mining activities. <br />From observations of the Laramie Formation at the Keenesburg Mine (Sec 25, T3N, <br />R64W) and from core obtained during exploration activities in Sec. 17, T3N, R63W, the <br />clayshales exhibit a condition of stress release within the formation. Slickened-sides or <br />"micro -faults" have very random orientations and are generally continuous for only a few <br />feet. Joint patterns have also been observed in areas of stress due to minor warping and <br />buckling of the Laramie Formation clays. These joint patterns were traced in the A -Pit <br />highwall at the Keenesburg Mine, and can be up to 35 feet in length. Displacements along <br />these near vertical failure planes are typically 0 ft. to .5 ft., but have been observed to be 5 <br />ft. to 15 ft. in areas of more intense faulting. <br />As a result of weathering, three zones occur within the clay -clay shale sequence of the <br />Laramie Formation. The first one, which underlies the unconsolidated eolian sands, <br />consists primarily of disintegrated, oxidized and weathered material generally 0 ft. to 10 ft. <br />in thickness, usually silty and sandy in nature. <br />The next underlying zone, which is approximately 2 to 20 feet in thickness, exhibits <br />moderate disintegration and contains numerous joints and slickened sides. This zone <br />generally has undergone moderate weathering and has become weaker, and is especially <br />unstable in the presence of water. <br />The third and lower-most zone has more widely spaced joints and slickened sides. Surface <br />moisture content and thus the degree of weathering is variable and not as extensive in this <br />zone. This material exhibits and overall higher strength than the overlying weathered clay <br />materials. <br />No preferred orientations of slickened sides, joint planes or fault plane surfaces have been <br />determined in the area; however, regional geological structure may suggest strike <br />orientations of larger features (faults, etc.) in a northwest -southeast direction. <br />Drill hole logs for the Keenesburg Mine area can be found in Appendix G. Physical and <br />chemical properties of the stratum within the overburden and interburden, and chemical <br />analysis of the coal seam are found in Appendix H (archived portion of Permit). <br />46 07/09 <br />