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Shale. The rock types most commonly observed consist of sandstones, <br />siltstones, shale, and coal. The bedrock associated with this parti- <br />cular project consists of the interbedded sandstones, siltstones, stales <br />and coals of the Mesa Verde group. At this particular location, however, <br />the bedrock itself is obscured by a thick deposit of colluvium and land- <br />slide type deposits. <br />FIELD INVESTIGATION: <br />The field investigation for this project consisted of an on-site <br />visual inspection and reconnaissancE: of the portal area, and the drill- <br />ing of tt.ree test borings located as shown on the Test Boring Location <br />Diagram. Test borings were advanced using a power-driven, continuous <br />flight auger driven by a CME Series 55 drill rig. Samples were typi- <br />cally obtained at 5-foot intervals in the soil profile, or staggered <br />as deemed necessary by our field representative during drilling. <br />Samples were obtained using the Standard Penetration Test, ASTM D-1586, <br />using a split barrel sampler. Bulk sampling methods were also utilized. <br />Results of standard penetration tests are shown on the drill logs to <br />the right of the sampling points. For example, a value of 11 blows/f t. <br />indicates that 11 hammer blows were required to achieve 12-inches pene- <br />tration of the sampling spoon into the soil strata. In all cases, the <br />standard penetration test was performed using a hammer weighing 140 lbs. <br />which was dropped from a height of 30-inches for each blow. Field logs <br />are available for inspection upon request to our office. <br />LABORATORY TESTING PROGRAM: <br />Moisture content, ASTM D-2216, was obtained in the laboratory for <br />all samples. A grain size analysis, ASTM D-422, and determination of <br />-3- <br />