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1 <br />6.0 CONCLOSIONS AND RECOMMENDATIONS <br />1 <br />6.1 PROPOSED ROCR CUTS <br />The stability analysis indicated that the rock cut will have a <br />' safety factor greater than 1.5 for all types of failure modes if <br />the slope is kept flatter than 0.5 horizontal to 1.0 vertical. <br />1 However, this stability analysis does not take into account <br />1 raveling or erosional slope stability problems. The shales in <br />the area may be needed to be protected with shot-crete or some <br />other means to prevent them from drying out. The drying out of <br />' the shales could cause shallow slope instability problems if they <br />are allowed to erode away which could possibly undermine the <br />massive sandstone formations. it is also recommended that a wall <br />be erected to catch the minor rock falls in the vicinity of the <br />' portal entrances. <br /> <br /> The geologic investigation, along with previous work in the area <br /> indicated there has been evidence of coal burn ar eas in the <br /> vicinity of the portal entrance. The burn ar eas can be <br />' characterized as having voids or accumulation of ash where the <br /> coal seam had been previously located. The November 1981 report <br />1 <br /> indicated that the rock masses above and the actual ash material <br /> have significantly lower shear strengths than the surrounding <br /> rock masses. The effects of the burn areas on the overall <br />' stability of the entire rock slope was not taken into account in <br /> this report due to the unknown extent of the burn a reas at the <br />1 <br /> site. These burn areas may require possible pinning or removal <br />' as identified during the removal of the rock if adverse <br />' 14 <br />