2013-05-03_GENERAL DOCUMENTS - M1974004

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Martin Marietta Materials Spec -Agg 2013 Annual Report 6.0 ANALYSIS OF STRUCTURAL DISCONTINUITIES The stability of the rock mass that forms the quarry walls is primarily controlled by the presence of rock discontinuities, such as joints, foliation, and faults. Discontinuities can create surfaces for sliding, and the intersections of multiple discontinuities can define the boundaries of wedges or blocks that have the potential to slide. The orientations of discontinuity sets vary considerably throughout the quarry. Therefore, it is possible that discontinuity orientations in a specific location of the quarry deviate from the discontinuity orientations assumed for the analyses presented in this report. 6.1 Evaluation of Discontinuity Measurements Representative discontinuity orientations for the quarry walls are required in order to evaluate the stability of the rock mass that forms the mine walls. Representative orientations for each discontinuity set observed were developed by analyzing the thousands of measurements collected since the beginning of the project. In the 2012 annual report, a total of nine (9) representative discontinuity sets were identified and analyzed for slope stability. For the 2013 annual report, we evaluated how the data collected over the past year compares with the previous geologic structure dataset and the representative orientations of observed discontinuity sets previously selected for analysis. Using this approach, we are able to assess possible emerging trends related to the shift in orientation of the various observed discontinuity sets as more of the rock mass is exposed during mining operations. Our slope stability analysis for the 2013 annual report is based on the updated representative discontinuity orientations based on the data collected during this study. We analyzed the discontinuity orientation data using DIPS 6.008 (Rocscience, 2013). The program enables plotting of individual data points, and offers several methods of data analysis, including contouring or cluster analysis. We plotted the individual data points collected during our October 2012 and March 2013 site visits over contours for the entire dataset, and alongside representative discontinuity orientations used for the 2012 annual report (Figure 4). In general, the data collected during our recent visits is consistent with the representative orientations of discontinuity sets observed in previous years, with a few exceptions. These exceptions include: 1) the absence of discontinuities representative of previously recognized joint set P -5 and foliation F -3, and 2) identification of a possible new representative joint set (P -7) based on clustering of some of the new data points with an orientation between joint sets P -1 and P -3 (Figure 6). We plotted and contoured individual data points from the 2012 -2013 annual site visits to help visualize the clustering of data from the recent measurements and to develop representative discontinuity orientations for use in kinematic analyses performed as part of this annual report (Figure 6). Individual data points are plotted by area (Main Pit versus Southern Expansion Area) to assist in evaluating whether some of the data trends are location specific. Representative discontinuity orientations of the nine (9) previously- recognized discontinuity sets from the 2012 annual report are shown for comparison. As shown in Figure 6, there is general consistency between the representative discontinuity orientations previously used for slope stability analysis and the contour peaks based on clustering of the new data, with some notable differences. We did not measure discontinuities this year that are representative of previously recognized joint set P -5 and foliation F -3. Arrows shown in Figure 6 indicate the apparent shifts in representative orientations of the observed discontinuity sets based on our evaluation of the new data. As April 22, 2013 Page 9 Lachel & Associates, Inc. Project 12361005 00 ©2013 All Rights Reserved