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As can be seen in Exhibits 3, 4, 5 and 6, all of the five cases which were investigated for r: the slope above the Portal Turnout share one characteristic. 'Che entire critical failure tt surface at this cross section takes place only within the steep slope above the upslope retaining •+vall of the Portal Turnout The critical failure surface, in the 5 cases studied was always in this steep upper slope portion; in not one case dicl the failure surface shear through or under the area to be backfilled (refer to the Exhit~its 3, 4, 5 and 6). It is evident that the dewatering system is the only variable having arty important effect on the absolute minimum factor of safety for the area above the portal turnout ' The conclusion !or this case is that the dewatering system for and above the Portal Turnout should always be operating to ensure a stable slope after reclamation. The immediate area below this steep upper slope and within the Portal Turnout itself was also investigated for stability in the post reclamation state. The modeling of the full cross section at Station 65+00 indicates, as noted previously, that the critical failure surfaces (those with the minimum Factors of Safety), in fact, lie above the Portal Turnout on the steep upper slope. By using this same model and selecting only those failure surfaces which intercepted the backfill zone of the Portal Turnout, one can compare the stability of this one part of the cross section with the stability of the overall section, especially that of steep upper slope above the Porto! Turnout The minimum Stability Factors of Safety for this isolated part of the cross section are much higher than those of the steep upper slope. These Factors of Safety are summarized in Table 3 below. TABLE 3 Reclamation Alternatives at Access Road Station 65+00 portal Turnout) with Corresponding Factors of Safety . Refer Dewatering Degree IIpslope 4linimum Case to Exhibit System left of Retaining wall Factor of Number Number In Place Compaction Left in place Safety 13 6 Yes 85% No 1.547* 14 6 Yes 95% No 1.546 15 6 Yes 85% Yes 1.807 * Result from linear interpolation These results show that the degree of compaction has little effect on the stability of the backfilled zone of the immediate Portal Turnout area. A significant increase in the stability of that region was realized, however, by leaving in place and burying the upslope retaining wa1L This is in contrast to the situation at Access Road Station 60+83 which showed that leaving the upslope retaining wall in place had no appreciable effect on post reclamation slope stability.