2009-12-04_REPORT - M2007014 - Laserfiche WebLink

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Joseph A Cesare and Associates, Inc. / Construction Technical Services During our November 2009 site visit, we noted the completion of a lower bench face with a height of up to 35 feet. The lower bench face had a strike ranging from N25 to N30V with a slope face of 67 to 65 degrees. A second bench above the first bench was being constructed. Measurements on both the lower and upper bench faces indicate bedding strike of N10 to N36V with dips of 29 to 35 degrees. This is in general agreement with the bedding plane orientation encountered during development of our December 2006 report. Clay seams were encountered along bedding planes in both benches. These seams were up to 6 inches thick and up to 30 feet in length. The longest seam of about 30 feet is shown in photographs 1 and 2, attached. It occurs about 12 feet from the base of the first bench face and has a dip of 34 degrees. These seams are discontinuous in nature but if this seam is continuous it should outcrop on the floor of the second bench about 20 feet from the open edge of the bench. Due to the presence of the clay seam, the recommendations provided in Reference 2 should be followed and a bench width of 48 feet should be maintained to provide for a long term stable highwall. When the width of the second bench is established, we should be contacted to observe the quarry at that time. Along the west pit wall the bedding planes dip into the cut face and the individual bench faces as constructed will undergo raveling and exhibit local instability. If you have any questions or comments in regards to this information, please feel free to contact our office. Sincerely, JOSEPH A. CESARE AND ASSOCIATES, INC./ CONS T ON TECHNICAL SERVICES � REGI jF •p _� Y ��' 919 ; Darin R. Duran, P.E. Principal, Geotechnical Engineering Manager DRD /ksm Attachments Project No. D09.210 2 92101tr.12.02.09