2020-11-05_REVISION - M1973021 (12)

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3. South and West Quarry Studies 3.1 Geotechnical Studies The locations of geotechnical drill holes advanced on site are summarized in Table 3-1 and shown in Figure 5. 3.1.1 Pre-2017 Geotechnical Explorations Several historical subsurface explorations have been performed in support of development and highwall design configuration of the South Quarry, ranging in depth from about 30 feet to about 700 feet in depth. Subsurface exploration campaigns were performed in 2005 by Lyman Henn, in 2007 by Al, in 2007 and 2008 by GEI, and in 2011 by Tetra Tech. In 2005, Lyman Henn advanced seven (7) HQ diameter boreholes and one NX diameter borehole (identified as LH-01 through LH-07). The borings were advanced to depths ranging from about 27 feet to about 195 feet. Retrieved rock cores were measured for percent recovery and the percent rock quality designation (RQD), retained in core boxes and photographed. The rock types encountered included granitic and biotitic gneiss, with some pegmatitic intrusions encountered. Samples from the borings were submitted for laboratory testing, consisting of LA Abrasion testing. In 2007, AI advanced three (3) vertical NQ diameter boreholes (identified as 2007 PH1-1 through 2007 PHI-3). The borings were advanced to depths ranging from about 300 feet to about 500 feet. Retrieved rock cores were measured for percent recovery, retained in core boxes, and photographed. Tetra Tech estimated percent RQD based on photographs of the rock cores. The rock types encountered included low grade migmatite, psammite, and meta pelite and the rock types and descriptions are essentially the same as granitic and biotitic gneiss encountered in other subsurface exploration campaigns. Samples from the borings were submitted for laboratory testing, including Micro Deval and LA Abrasion testing. In 2007 and 2008, GEI advanced three (3) vertical HQ diameter boreholes and four HQ diameter boreholes inclined at 70' from horizontal (identified as 2007 PH 2-1 through 2007 PH 2-3 and 2008 PH 3-1 through 2008 PH 3-4). The borings were advanced to depths ranging from about 300 feet to about 685 feet. Retrieved rock cores were measured for percent recovery, retained in core boxes, and photographed. The rock types encountered included granitic and biotitic gneiss, with some pegmatitic intrusions encountered. Samples from the borings were submitted for laboratory testing, including Micro Deval and LA Abrasion testing. In 2011, Tetra Tech advanced one vertical HQ diameter borehole to a depth of 690 feet (identified as TT-01). The retrieved rock core was measured for percent recovery, RQD, retained in core boxes and photographed. The rock types encountered included granitic and biotitic gneiss, with some mafic dike intrusions, pegmatitic intrusions, and sillimanitic 10 Aggregate Industries—Morrison Quarry GEI Consultants, Inc. AM-07 Geotechnical Stability Exhibit November 2020