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<br />• <br />INVESTIGATION <br /> <br />The field investigation included site observations, drilling of exploratory <br />borings and measuring groundwaterin the borings. Seven borings were drilled to <br />depths of 25 to 70 feet at the locations shown on Fig.1. The test holes were drilled <br />using 4-Inch O. D. solid-stem augers powered by struck-mounted drill rig. The solid <br />augers were removed at 5 to 10-foot intervals, and samples were obtained with a <br />California-type (2.5-inch O. D.) drive sampler. Bulk samples of the overburden soils <br />were also obtained off the augers. Graphic logs of the borings are presented in <br />Appendix A. <br />Boring locationswere selected byCTL~Thompson, Inc. and were restricted <br />due to access. The boring location and elevation were measured by Colowyo. <br />Colowyo also performed delayed ground water measurements. <br />Samples obtained during the field investigation were returned to the <br />CTL~Thompson, Inc. laboratory for testing which included: <br />1. Moisture content and density testing on drive samples from the <br />exploratory borings; <br />2. Classification testing including Atterberg limits and gradation; and <br />3. Amoisture-density relationship (ASTMD698),twodirectsheartests, <br />and a consolidated undrained (CU) triaxlal strength test with pore- <br />pressure measurements were performed on samples of the <br />overburden Bolls. <br />One direct shear test was performed on intact, driven liner samples. One <br />direct shear test was performed on a bulk sample remolded to about 93 percent of <br />ASTM D 698 maximum dry density. The CU test was also performed on a similarly <br />remolded sample. The remolded samples wererecompactedandtestedwiththe+ <br />3/e-inch particle sizes removed and not replaced. Laboratory test results are <br />NENNECDIT ENERDY <br />COLOWYO COAL COMPANY-SOUTH TAYLORSEOIMENTATION POND <br />C1L~T JOB NO. JB,BBI 3 <br />• Exh. 7-20F-7 Revision Date: 1/05/07 <br />Revision No.: PR-02 <br />