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Martin Marietta Materials <br />Spec -Agg 2013 Annual Report <br />7.0 CONCLUSIONS AND RECOMMENDATIONS <br />The results of the structural geologic evaluation and kinematic rock slope stability assessment for the Spec - <br />Agg Quarry does not indicate any immediate concerns with respect to large -scale instabilities in the current <br />final quarry wall faces based on our field observations and current rock mass assumptions. The stability of <br />the slopes is enhanced by the absence of significant hydrostatic pressures, by current mining procedures <br />and by the current reclamation process being implemented by Martin Marietta at the site. While large -scale <br />failures are not anticipated, the slope will continue to shed rocks over time as a result of small -scale failures, <br />particularly in near - vertical temporary bench faces. <br />For the 2013 annual report, kinematic analyses are based on representative discontinuity measurements <br />derived principally from data collected during the October 2012 and March 2013 site visits. The results of <br />these analyses are not intended to supersede results of analyses performed for prior years that were based <br />on representative discontinuity orientations generated from the entire dataset of measurements. Rather the <br />analyses presented herein are meant to compliment previous years' analyses and enable monitoring of <br />possible new trends in the data that could result in previously unconsidered failure modes. <br />In general, the data collected during the October 2012 and March 2013 site visits correspond reasonably well <br />with representative discontinuity orientations used in previous reports; however, we noted some differences <br />which we applied to our kinematic analyses for the 2013 annual report. <br />The kinematic analysis for East Walls 1 and 2, Northeast Wall 3, and West Wall 3 each indicate the <br />possibility for wedge failures to occur. Additionally, the analysis for Northeast Wall 3 shows the potential for <br />planar failure. The walls of the quarry in these areas should continue to be monitored closely as mining <br />continues to assess the potential for the indicated failure modes to contribute to large -scale slope instability <br />of a final mine highwall based on the continuity, regularity and variation in orientations of the discontinuities <br />involved. <br />We also recommend that known faults are tracked and observed in new exposures to confirm orientation and <br />character for supplemental stability analysis, as needed. We expect the southern fault identified by Gable <br />(1968) and in previous years site visits (Figure 3) may be exposed in other locations as excavations continue <br />in the Southern Expansion area. Additionally, the unmapped fault generally located in the central portion of <br />the quarry may be exposed for mapping in the future. <br />As documented in the past, localized raveling, especially along the south walls is likely to continue. <br />Continuation of the safety- minded policies already in place, which limit the height of the exposed highwall as <br />well as the reclamation of exposed highwalls as soon as possible following blasting and rock haulage, will aid <br />in minimizing the potential for instabilities to occur. <br />April 22, 2013 Page 17 Lachel & Associates, Inc. <br />Project 12361005.00 ©2013 All Rights Reserved <br />