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t <br />i <br />6.0 Summary and Conclusions <br />The results of the structural geologic evaluation for the Spec-Agg Quarry, which <br />included field observations, geologic mapping, and stereographic analysis of structural <br />geology data, indicate that the current quarry configuration is stable under the existing <br />conditions and current rock mass assumptions. The stability of each of the slopes is <br />enhanced by the absence of significant hydrostatic pressures, by current mining <br />procedures, and by the current reclamation process. <br />F-3, the additional foliation set was initially identified in the 2005 study. To date, not <br />enough data have been collected to fully develop a hypothesis regarding the location, <br />extent and properties of the foliation; or to eliminate the possibility that F-3 is basically a <br />signature of the undulating nature of the existing foliation set. The stereographic <br />analysis indicates that the F-3 discontinuity plane may only have minor influence on the <br />south walls, and will not influence the north, west or east walls. <br />Evaluations will be conducted during future investigations to evaluate whether or not <br />any of the foliation sets (F-1 through F-3) are caused due to localized faulting that may <br />have resulted in "structural region" that have created areas in which the varying foliation <br />planes occur. These questions will continue to be addressed as more data are <br />collected. <br />With respect to the quarry walls, the north walls are currently being mined at a slope <br />angle of approximately 35° and are currently stable; and as stated in previous reports <br />the slide that occurred on the northeast wall has shown no signs of continued <br />movement since the steepness of the wall slope was modified in 1999. Based on data <br />collected from boreholes in the 2003 geotechnical investigation, a number of relatively <br />shallow foliation surfaces will be encountered below the current main pit elevation of <br />6,340 feet, starting at an estimated depth of 6,325 feet and the north walls should be <br />monitored closely as the final 140 feet of excavation occurs. <br />-20-