2017-06-27_REPORT - M1973021 - Laserfiche WebLink

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Aggregate Industries Morrison Quarry GEI Consultants, Inc. Geotechnical Addendum, 2016 Annual Report 7 January 2017 Some material stripped from areas within the South Quarry in 2016 was deposited in the Central Quarry as part of quarry reclamation (Fig. 3). The existing grade in the quarry is approximately El. 6500. Excess material is being temporarily stockpiled in the south end of the quarry above E. 6500 for future use in South Quarry reclamation. 3.3 South Quarry Geotechnical data was collected for areas mined in the South Quarry in 2016. These areas included three mined highwalls from benches at El. 7113, 6850, and 6600. Several highwalls were not mapped because the benches below them were either inaccessible or because there were active mining operations occurring on or above them at the time of geotechnical observations. These unmapped benches include Bench 6900, Bench 6950, Bench 7000, Bench 7033, and Bench 7073 (Fig. 27 and 28). Mining during 2016 deepened the South Quarry by 40 feet (beyond El. 6640 established in 2012) by establishing a new bench at El. 6600. Mining also expanded extraction to the south (north facing) and west (east facing). AI indicated that a total of four highwalls have been fully reclaimed and seeded since 2014. The 2015 geotechnical addendum indicated that Bench 7550 and Bench 7520 had been fully reclaimed and seeded. Bench 7480, and Bench 7450, which were only partially reclaimed in 2015, are now assumed to be fully reclaimed and seeded. Several reclaimed and partially reclaimed highwalls could not be safety accessed due to the removal of haul roads that formerly provided access to the upper highwalls. GEI personnel hiked up to a partially reclaimed highwall at El. 7270 but the bench was not wide enough to safely collect geotechnical data. Fig. 27 shows a distant view of the South Quarry from the east and reclaimed, partially reclaimed, and active benches are highlighted. The rock type observed within the South Quarry is consistent with rock type found within the North and Central Quarries, as well as rock type found at the South Quarry which has been described in previous geotechnical addenda. The rock type of the South Quarry is generally described as fine- to medium-grained granitic gneiss or biotite gneiss. Occasional intrusions are present in the granitic gneiss. Intrusions are composed of biotitic gneiss and pegmatitic material. Shear zones are also present and visible. Shear widths range from several inches to approximately 20 feet. The rock type is typically slightly weathered to moderately weathered. Several highwall sections are more highly weathered. These sections are typically in areas proximal to the original (pre-mining) ground surface. Two prominent joint sets are visible throughout the South Quarry with prominent foliation. Joint sets are spaced by several inches to approximately 10 feet. The typical aperture of the joint sets is approximately one-tenth of an inch. Larger apertures are likely the result of mine blasting. The rock surfaces of the prominent joint sets are typically slightly rough to rough; joint openings range from very tight to moderately open. Iron staining is present on most joint faces, with less staining