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File No. 20-1100-38 KLEINFELDER September 12, 1996 r • Discussions and results of slope stability analyses III. SITE CONDITIONS The proposed sand and gravel operations area is fairly level and consists of mostly orchard. The site is bordered by an existing aggregate pit to the north, mostly agricultural land to the south and east,and MacArthur Drive to the west. IV. FIELD EXPLORATIONS The field explorations were performed on September 6, 1996, and consisted of drilling a total of two test borings to supplement Teichert's test borings. The locations of our borings,as well as the locations of borings completed by Teichert and reviewed for this study, are shown on Plate A-1. The borings were drilled to depths of approximately 75 feet below the existing ground surface. _ The borings were located by pacing in the field and were drilled with truck-mounted drill equipment using 8-inch diameter, hollow-stem augers. Continuous logs of the materials encountered in the borings were maintained by an engineer from our firm who assisted in obtaining relatively undisturbed soil samples from the borings for visual observation, classification, and laboratory testing. Attempts were made to recover relatively undisturbed samples of the soils encountered, primarily in those zones where tip resistance indicated loose gravelly deposits. However, in most instances, it was not possible to recover testable samples because of the gravelly or dense nature of the materials. Soil samples were obtained by driving an approximate 2-inch, inside-diameter sampler into the soils using a 140- pound hammer falling approximately 30 inches. The number of blows required to advance the sampler into the last 12 inches of soil is presented on the Logs of Borings, Appendix, Plates A-3 and A-4, at the corresponding sample locations. After borings were completed, they were backfilled with either hole plug or the drill cuttings in accordance with San Joaquin County Public Health Services requirements. V. SOIL CONDITIONS The surface soils encountered in our borings generally consisted of gravelly soils with occasional thin lenses of silts and clays. The borings drilled by Teichert also consisted of gravelly soils with interbedded lenses of clay and silts. The last 13 feet of Boring B-2 caved. Based on the manner of drilling and experience in the area, we conclude that the sand and gravel deposits encountered in our borings are partially cemented. The silt and clay deposits encountered in the Teichert borings are most likely also partially cemented. We note that similar silt and clay soils exposed in deep excavations adjacent to the site still show teeth marks left by excavating equipment years earlier. 10-1100-381MR960198 Page 2 of 6 ®1996, Kleinfelder,Inc.