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I' M04007MT <br />' inclinations ranging from two and three-quarters to one (2 3/4 :1) <br />' to four to one (4:1) (horizontal to vertical) depending on the gob <br />strength characteristics used. The four to one (4:1) slope face <br />inclination was associated with strength characteristics of the 75 <br />' percent gob/25 percent clay and the two and three-quarters to one <br />(2 3/4 :1) slope face inclination was associated with strength <br />characteristics of the 100 percent gob. The slope stability <br />' analysis for the proposed flatter slope inclinations on the gob <br />pile is presented on Figures C and D. <br />' Our stability analysis included an existing cross section of the <br />gob pile. The existing cross section is located at or near the <br />maximum height of the proposed gob pile fill and has an existing <br />' height of one hundred (100) feet. The analysis was performed by <br />varying the slope face inclinations from two to one (2:1) <br />(horizontal to vertical) and flatter to determine a theoretical <br />' calculated factor of safety of 1.5 or greater for the existing <br />embankment. The stability analysis of the existing cross sections <br />indicates a theoretical factor of safety of about 1.5 or greater <br />for slope face inclinations ranging from two to one (2:1) to two <br />and one half to one (2 1/2:1) depending on the gob strength <br />characteristics used. The two to one (2:1) slope face inclination <br />' was associated with strength characteristics of the 100 percent gob <br />and the two and one half to one (2 lh :1) slope face inclination was <br />associated with strength characteristics of the 75 percent gob/25 <br />' percent clay. The slope stability analysis for the existing gob <br />pile is presented on Figures E and F. <br />' It should be noted that the coal gob strength characteristics are <br />based on limited sampling. We suggest that additional laboratory <br />strength tests be performed on the coal gob material during <br />' placement about every ten (10) feet of gob fill height or about <br />twice per year, whichever occurs more frequently, to verify that <br />' the material characteristics and strength do not vary <br />significantly, with time and mined material changes. <br />' 4.0 POST DESIGN CONSIDERATIONS <br />' The project geotechnical engineer should be consulted during <br />construction of the project to observe site conditions and open <br />6 <br />~am6ert ana ~,s~,oociates <br />CONSULTING GEOTECN NICAL EN6INEER3 ANO <br />MATERIAL TESTING <br />