2014-05-02_REPORT - M1974004 - Laserfiche WebLink

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Martin Marietta Materials Spec -Agg 2014 Annual Report 5.0 FIELD OBSERVATIONS Field observations for the 2014 annual report consisted of rock structure mapping and collecting information regarding areas of visible large -scale instability, seepage, and mining activity. Observations for the current annual report were made during two site visits, which took place in November 2013 and March 2014. We performed rock structure mapping during the two site visits to collect representative discontinuity measurements from recently mined rock exposures in the Southern Expansion Areas (Figure 2; Photos 1 through 3). Orientation measurements (i.e., dip /dip direction) of joints, foliation, and faults were taken from the faces of advancing benches. A geological compass was used to obtain discontinuity measurements both indirectly by sighting along the discontinuity surfaces and, where deemed safe, by direct measurement on the discontinuity surfaces. A handheld GPS was used to record the location of data collection points (Figure 2). A total of 59 discontinuity measurements were collected at six data collection points, and were added to the measurements from previous years. When combined with data collected from previous annual reports (1997 -2002, 2004 -2013) and with borehole geophysical data collected during the 2003 geotechnical investigation, a total of 3,222 discontinuity orientation measurements have been obtained over the past 17 years. Figure 5 shows the 59 discontinuity orientation measurements collected for this annual report overlain on a contour stereonet plot of the entire Spec -Agg structural dataset. During our March 2014 site visit, we observed a newly exposed fault along the temporary excavation wall in the Southern Expansion Area at station 14 -04 (Figure 3 and Photo 3). The fault is oriented approximately northeast - southwest, with dip /dip direction of 62/135. The fault was exposed in the western margin of the expansion area during previous site visits. The fault zone consists of weathered, broken and blocky rock, with parallel fracturing, and iron - stained slickenside surfaces with locally clayey gouge. The apparent width of the fault zone varies in from 6 to 10 ft. The fault orientation measurements for this annual report are presented with previous fault measurements and differentiated by the fault feature they represent in Figure 4. Minor raveling conditions resulting from rock fragmentation during blasting and subsequent freeze /thaw conditions exist along each wall in the quarry, but appear more prevalent along the south wall possibly due to the north facing exposure. The quarry walls observed during the site visits performed for this annual report appeared to be relatively dry; and noticeably absent is any major seepage in the southwest corner of the main pit, which had been documented in prior reports as having occasion seeps visible. No major seepage was observed. During our November 2013 and March 2014 site visits, we observed standing water in the sump of the main pit; however, the sump pump was not operating (the pump operates 3-4 hours per day in normal condition). The main pit floor was dry during our March 2014 visit. Reportedly, during the September 12 -13, 2013 historic rainfall event in Colorado, water flowing from highwalls caused some minor damage to temporary rock barriers along the temporary quarry access road. March 31, 2014 Page 6 Lachel & Associates, Inc. Project 13364013 00 02014 All Rights Reserved