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Martin Marietta Materials <br />Spec -Agg 2013 Annual Report <br />6.4.4 West Walls <br />For the 2013 annual report, we analyzed three west wall orientations based on the locations shown in Figure <br />2 and Table 2: West Walls 1 through 3. The wall locations and orientations correspond to the same wall <br />locations and orientations analyzed in previous annual reports. We analyzed West Wall 1 using the 2013 <br />representative discontinuity measurements for the Main Pit area because that wall lies directly west of the <br />Main Pit (Figure 2). For West Walls 2 and 3, located south of West Wall 1, we performed our kinematic <br />analyses using the 2013 representative orientations for the Southern Expansion Area. The difference in the <br />representative discontinuity orientations used in the analyses is that joint set P -4 was included for the Main <br />Pit and joint set P -6 was included Southern Expansion Area (Figure 7). All other representative discontinuity <br />orientations were considered in both areas. <br />The stereonet plot for West Wall 1, adjacent to the Main Pit area, does not indicate the potential for wedge or <br />planar failure modes (Figure 11). <br />The stereonet plot for West Wall 2, adjacent to the Southern Expansion area, does not indicate the potential <br />for wedge or planar failure modes (Figure 12). <br />The stereonet plot for West Wall 3 shows one discontinuity intersection that falls within the critical zone, <br />suggesting that wedge failure is kinematically possible for this slope orientation (Figure 12). The intersecting <br />set that may result in wedge failure includes foliation F -1 and joint P -2. The signatures of both F -1 and P -2 <br />appear to be relatively weak in the Southern Expansion Area since only one measurement of each of these <br />representative discontinuity sets was observed there (Figure 6). In contrast, multiple measurements were <br />recorded for these discontinuity sets in the Main Pit. The development and size of wedge failures will be <br />controlled by the variability and limited lateral extent of the discontinuities. As excavation proceeds for West <br />Wall 3, additional measurements are needed to refine the representative discontinuity orientations of these <br />joint and foliation sets in this area to evaluate their potential contribute to large -scale slope failure modes. <br />Our analysis indicates that potential planar failure may form in individual benches along the South West Wall <br />1 with near vertical faces during the temporary conditions prior to reclamation. <br />6.4.5 Southern Walls <br />For the 2013 annual report, we analyzed four southern wall orientations based on the locations shown in <br />Figure 2 and Table 2: Southwest Walls 1 and 2, the South Wall, and the Southeast Wall. The wall locations <br />and orientations for the Southwest and Southeast Walls correspond to the same wall locations and <br />orientations analyzed in previous annual reports. The South Wall is a newly analyzed wall orientation for the <br />2013 annual report (Figure 2). We analyzed the southern walls using only 2013 representative discontinuity <br />measurements for the Southern Expansion area (i.e., including joint P -6 and excluding joint P -4). <br />The stereonet plots for Southwest Walls 1 and 2, the South Wall, and the Southeast Wall do not show <br />indications of potential planar or wedge failure modes based on the 2013 representative discontinuity <br />measurements (Figures 13, 14, and 15). <br />April 22, 2013 Page 15 Lachel & Associates, Inc. <br />Project 12361005.00 ©2013 All Rights Reserved <br />