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Meazurement of the groundwater level was made in the test hole by lowering a weighted tape into the open hole shortly after completion of the drilling. The depth to the groundwater measured is shown on the Log of Exploratory Tes[ Hole. LABORATORYINVESTIGATiON The laboratory investigation was conducted to study the engineering characteristics of the materials obtained in the test hole and two relatively undisturbed hand drive samples which were obtained during the construction of the embankment. This section includes a discussion of the laboratory test procedures, figures and tables presenting the actual test results. ' Samples obtained from the test hole were examined and classified in the laboratory by the project engineer. Laboratory testing included standard property tests such az natural moisture contents, dry density, grain size analyses, liquid and plaz[ic limits and strength tests. Results of the laboratory testing program are shown on Figures #2 & #3 and are summarized in Table 1. The laboratory testing was conducted in general accordance with recognized test procedures, primarily [hose of the American Society for Testing and Materials (ASTM). index Properties: [n order to identify soils and classify them into categories of similar engineering properties, the Unified Soil Classification System (ASTM D-2487) was used. This system is based on index property tests, including the determination of natural water content (ASTM D-2216), liquid limits (ASTM D-423), plastic limits (ASTM D-424) and grain size distribution (ASTM D-422). Results of the moisture content, dry density, Atterberg limits and the percent of soil passing the U.S. No. 200 sieve are presented in Table 1. Unconfined Compressive Strength: Unconfined compressive strength testing was conducted on samples of the • embankment fdl materials, as well as a sample of the natural clays. Each sample was prepared by cutting the end of [he specimen parallel to each other and at right angles to the longitudinal axis of the core. Load was applied continuously and without shock to produce a constant rate of deformation while the test was performed. Results of the unconfined compressive strength testing are discussed later in this report and are summarized in Table 1. Triaxial Shear Tes[ine: Triaxial shear testing was on performed on relatively undisturbed samples of the natural clays taken from below the embankment. In addition, triaxial shear testing was completed on remolded samples of the embankment materials. The test consisted of subjecting a cylindrical specimen to an all-around pressure and an axial load varied independently of the all-around pressure. The all-around pressure was applied in a fluid-idled chamber and the axial load was applied by means of a piston passing through the chamber top. The specimens were tested after triaxial chamber pressures were increased to the desired confining pressure. Axial load and sample strain were monitored az the axial load was increased to failure. Results of the triaxial tests are presented in Figures #2 and #3 and are discussed later in this report. SUBSURFACE CONDITIONS Based on our observations made at the site and the compaction tests taken during the construction of the embankment, and our observation of the test hole drilled in the center of the dam, it appears that the majority o[ the Gll materials consisted of clays which were slightly sandy to sandy with occasional sandstone fragments, ~ . low to moderately plastic, stiff to very stiff, moist and brown in color. The clay Fill materials generally classified-~ JoM1 No. 95-2784 Northwest Colorado Consultants. Inc. Poge