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<br />Aggregate Industries Morrison Quarry GEI Consultants, Inc. <br />Geotechnical Addendum, 2016 Annual Report 14 January 2017 <br />4. Results and Discussion <br />Based on observations made during the 2016 geotechnical field review of the Morrison <br />Quarry performed in January 2017, GEI staff familiarity with the site, and review of previous <br />geotechnical addenda, the North Quarry has experienced little change in finished slope <br />characteristics during 2016. Only small-scale, localized rockfall and highwall raveling <br />occurred during the last year and are considered minor. GEI recommends that AI continues <br />to monitor the highwalls for signs of increased instability. While localized tension cracks <br />observed in 2013 near the quarry office safe zone were not visible during the 2016 review, <br />this area should also be monitored for signs of instability such as visible slope movement <br />and/or tension cracks. The condition of the main trunk of the North Quarry is expected to <br />remain stable during the course of the 2017 mining year with continued small-scale rockfall <br />and highwall raveling expected to occur. <br />Based on observations made during the 2016 geotechnical field review of the Morrison <br />Quarry performed in January 2017, GEI staff familiarity with the site, and review of previous <br />geotechnical addenda, the Central Quarry has experienced little change in finished slope <br />characteristics during 2016. Only small-scale, localized rockfall and highwall raveling <br />occurred during the last year and can be considered minor. The condition of the <br />Central Quarry is expected to remain stable during the course of the 2017 mining year with <br />continued small-scale rockfall and highwall raveling expected to occur. Reclamation was <br />substantially completed in 2016, bringing the floor of the quarry to an elevation of <br />approximately 6500 feet. Seepage emanating from the west (east facing) highwall at <br />approximate El. 6600 is considered minor (<2 – 3 gpm) and appears to not have impacted <br />highwall stability. Although the seepage was noted in the 2013 addendum and no increase in <br />seepage was observed in the 2016 review, the seepage area should be monitored in 2017 for <br />increased flow rates, spreading, instability, etc. This area is not anticipated to impact highwall <br />stability in 2017. Fig. 25 includes a year over year comparison from 2014 through 2017. <br />Amendment 3 to AI’s Morrison Quarry Mining Permit M-1973-021 establishes requirements <br />for rock stability at the Morrison Quarry. Granite and biotitic gneiss should be considered <br />“competent”; rock and shear zones or highly weathered rock should be considered “poor” <br />rock if the zones have the ability to decrease the overall stability of quarry highwalls and/or <br />benches. The observed conditions in the newly-mined areas of the South Quarry are of <br />predominantly “competent” rock quality. Localized “poor” zones were observed during the <br />2016 review. These “poor” areas are typically the result of highwall proximity to pre-mining <br />topography ground or zones of sillimanitic gneiss. <br />Changes in the Bench 6820 instability area were not observed during the 2016 review. GEI <br />noted that mining activities above Bench 6820 have caused material to accumulate on the <br />bench (Fig. 26). This is occurring along the entire bench, including the area of instability.