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CONCLUSIONS <br />Based on our observations made during the construction of the subject embankment, the subsurface conditions <br />encountered in the test hole drilled in the center of the dam and the slope stability analysis completed by our <br />firm, we believe that the subject embankment waz constructed in general accordance with the project plans and <br />specifications and should perform adequately. Based on the slope stability analyses, the embankment, as <br />constructed, and the underlying bearing soils exhibited a minimum Factor of Safety against failure of 1.84 under <br />seismic loading and 3.26 under static loading. These factors of safety exceed the minimum Factor of Safety <br />(1.3) required by Rule 4.05.6(11)(k). <br />PURPOSE AND SCOPE OF STUDY <br />This report presents the results of a geo[echnical investigation and construction summary for the Pond 010 <br />embankment which was constructed at [he Yoast Mine in Routt County, Colorado. <br />A field exploration program was conducted to obtain information on subsurface conditions. Material samples <br />obtained during the subsurface investigation were tested is the laboratory to provide data on the clazsitica[ion <br />and engineering characteristic of the natural soils cad bedrock below the embankment and the embankment <br />fill materials. The results of [he Geld and laboratory investigations are presented herein. !n addition, we <br />observed the construction of the embankment and tested [he embankment fill materials for compaction on a <br />par[-time basis. <br />• This report has been prepared to summarize the data obtained and to present our conclusions and <br />recommendations based on [he completed construction and [he subsurface conditions encountered. <br />FIELD INVESTIGATION AND OBSERVATIONS <br />Our fum observed the construction of the embankment and tested the compaction of the embankment <br />materials on a part-time basis from July 31, 1996 to August 12, 1996. In addition, Mr. Brian Len, P.E., visited <br />[he project site on July 24, 1996 to observe the topsoil stripping operations and the subgrade soils prior to <br />construction of the embankment. Copies of the daily test reports, as well as a copy of the report prepared by <br />Mr. Len after his visit on July 24, 1996 are enclosed in Appendix A. <br />To determine the subsurface conditions below the subject embankment and to verify the strength and <br />compaction of the embankment fdl materials, a [es[ hole was drilled through the completed embankment on <br />August 12, 1996. The test hole was advanced through the embankment materials and into the natural soils and <br />bedrock with atrack-mounted CME 45 drill rig utiliLag 4-inch diameter continuous flight power augers. The <br />[es[ hole was logged by a representative of Northwest Colorado Consultants, Inc. A log of the test hole and the <br />associated Legend and Notes are shown in Figure #1. <br />Samples of the subsurface materials were taken with a 2-inch I.D. spoon sampler. The samplers were driven <br />into the various strata with a 140-pound hammer falling 30 inches. This test is similar to the standard <br />• penetration test described by ASTM Method D-1586. Penetration values, when properly evaluated, indicate the <br />relative density or consistency o(the soils and bedrock. Depths at which the samples were taken are shown on <br />[he Log of the Exploratory Test Hole. <br />Job No. 95-?38J Northwest Culora~o Consulian~s. Inc. Pagc I <br />