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Martin Marietta Materials Spec-Agg 2016 Annual Report As excavation proceeds for West Wall 3, additional measurements are needed to refine the representative discontinuity orientations of these joint and foliation sets in this area to evaluate their potential contribute to large-scale slope failure modes. 6.4.5 Southern Walls For the 2016 Annual Report, we analyzed four southern wall orientations based on the locations shown in Figure 2 and Table 2: Southwest Walls 1 and 2, the South Wall, and the Southeast Wall. The wall locations and orientations for the Southwest and Southeast Walls correspond to the same wall locations and orientations analyzed in previous annual reports (Figure 2). The stereonet plots for Southwest Walls 1 and 2 do not show indications of potential planar or wedge failure modes based on the 2015 discontinuity measurements (Figure 13). However, even a slight variability of the joint sets P-2 and P-4 will have potential to form wedges within the critical zone for these walls. The stereonet plot for the South and Southeast Wall shows one discontinuity intersection that falls within the critical zone, suggesting that wedge failure is kinematically possible for this slope orientation (Figures 14 and 15). The intersecting sets that may result in wedge failure includes joint sets P-3 and P-6. The signatures of P-6 appears to be relatively strong in the Southern Expansion Area (Figure 6) based on the 2013-2014 and 2015 data. The development and size of wedge failures will be controlled by the variability and limited lateral extent of the discontinuities. As excavation proceeds for the Southern Walls, additional measurements are needed to refine the representative discontinuity orientations of these joint and foliation sets in this area to evaluate their potential contribute to large-scale slope failure modes. 7.0 CONCLUSIONS AND RECOMMENDATIONS The results of the structural geologic evaluations and kinematic structural discontinuity analyses for the Spec-Agg Quarry do not indicate any immediate concerns with respect to large-scale instabilities in the current final quarry wall faces based on our field observations and current rock mass assumptions. The stability of the slopes is enhanced by the absence of significant hydrostatic pressure, by current mining procedures, and by the current reclamation process being implemented by Martin Marietta at the site. While large-scale failures are not anticipated, the slope will continue to shed rocks (minor raveling) over time as a result of small-scale failures (planar or wedge failure), particularly in near-vertical temporary bench faces. For the 2016 Annual Report, kinematic analyses are based on discontinuity measurements derived principally from data collected from the existing growing dataset supplemented with data collected during the July and December 2015 site visits. The results of these analyses are not intended to supersede results of analyses performed for prior years that were based on representative discontinuity orientations generated from the entire set of measurements. Rather the analyses presented herein are meant to compliment previous years' analyses and enable monitoring of possible new trends in the data that could result in previously unconsidered failure modes. The collected data for this evaluation was complimentary to and were consistent with past analyses. It is noted that the results for the current analysis did not change the pole or the resultant concentration center for any of the delineated joint sets significantly from any of the recent years' results. In general, the data collected during the July and December 2015 site visits correspond reasonably well with representative February 8, 2016 Page 11 Lachel & Associates, Inc. Project 15364004.00 02016 All Rights Reserved