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' I - 16 - ' prove proper understanding of the stability problem. Even if ' such analyses do not provide accurate quantitative results, a qualitative evaluation is often valuable for preliminary design ' purposes. For this reason, we have carried out a series of stabili- ' ty analyses, using the existing topography and fairly well- defined geologic profile. The geotechnical profile - C-C' as , ' indicated on Plate 1, Site Map, and Plate 5, Geotechnical Profile C-C' were used for this purpose. Another typical pro- ' file (Profile B-B') is shown on Plate 4. The geology of this section is fairly well-known, even if some interpretations had ' to be made on the extent of the landslide deposits. The section includes two coal seams, the F and E seams. Hydrological con- ' ditions are practically unknown, and only very rough approxi- mations could have been made. As we suspect that ground water may temporarily or permanently occur mostly within the per- ' vious layers of the formation, we assumed that it exists either with the F or the E seam. It was assumed, for the pur- ' pose of our analyses, that the seams are confined aquifers and that the piezometric head is 40 feet above the bottom of the coal seam. This number is rather arbitrary, and it is based on the back-calculations which were carried out prior to ' the analyses. The mode of the failure plane or of individual failure ' planes was also interpreted. In concordance with the earlier discussions of this report on the mechanism of the slides, it ' was assumed that the failure plane develops along the bottom of any of the coal seams. The upper section of the failure ' plane within the coal overburden was developed by the com- puter model. The failure plane section in the landslide de- t 1 posits was also developed by the computer model. e¢w+rono coruuinNC, iNC.