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3.1 Test Pit RC-01 <br /> Test pit RC-01, at approximately Station 19+31, was excavated to collect an additional <br /> bulk sample for geotechnical testing. The sample will be subjected to a compaction test per <br /> ASTM D 1557—09, to support access road construction. <br /> 3.2 Test Pit RC-02 <br /> Test pit RC-02 was excavated to assess the extent of and depth to bedrock on the <br /> outboard side of the access road in the vicinity of the MSE wall, approximately between Stations <br /> 18+52 and 18+96 (Sheet S 1, Appendix Q. <br /> The material encountered in the test pit consisted of loose to medium silty sand fill <br /> material that includes gravel, cobbles, and boulders overlying bedrock. Bedrock consisted of <br /> siltstones, claystones, and minor sandstone layers of the Morrison Formation. The siltstones and <br /> mudstones at the surface could be broken by the backhoe, but the sandstones encountered were <br /> more competent. Bedrock surface sloped from the south edge of the excavation to a depth of 5 <br /> feet, then descended vertically to a depth of 14 feet, and remained at that depth to a point 17 feet <br /> from the edge of the existing road. <br /> 3.3 Test Pit RC-03 <br /> Test pit RC-03 was excavated to assess the extent of and depth to bedrock on the <br /> outboard side of the road in the area for the proposed alternate MSE wall, approximately <br /> between Station 18+76 and Station 18+92 (Sheet S 1, Appendix Q. <br /> The material encountered Test Pit RC-03 consisted of a loose to medium silty sand fill <br /> material that includes gravel, cobbles, and boulders overlying bedrock. The bedrock was <br /> consistent with the bedrock in Test Pit RC-03. It sloped from the south edge of the excavation to <br /> a depth of 5 feet, remained level for 3 feet, descended vertically to a depth of 8 feet, and sloped <br /> to a depth of 14 feet to a point 23 feet from the edge of the existing road. The proposed MSE <br /> wall at Station 18+86 is shown on Figure 3. <br /> 3.4 Test Pit RC-04 <br /> Test pit RC-04 was excavated to assess the extent and depth to bedrock in the area for the <br /> proposed alternate gravity wall, approximately between Station 17+74 and Station 18+52 (Sheet <br /> S 1, Appendix Q. The material encountered in the test pit consists of loose to medium silty sand <br /> fill material that includes gravel, cobbles, and boulders overlying bedrock. The bedrock was <br /> consistent with the bedrock in Test Pit RC-03. Bedrock sloped from the south edge of the <br /> excavation to a depth of 9 feet at a distance 8 feet out from the edge of the existing road, then <br /> appeared to descend vertically — the test pit extended to a depth of 14 feet with no bedrock <br /> encountered, sloping to 19 feet in fill material. The 19-foot depth extended to a distance of 22 <br /> feet from the edge of the existing road with no bedrock encountered. <br /> Supplemental Geotechnical Investigation April 29,2014 <br /> New Access Road Page 2 <br />