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^ ,. <br />Twin Pines No. 2 Mine <br />April 10, 1990 <br />Page -2- <br />Spoils Material Tests <br />Laboratory tests were performed on representative soil samples to <br />determine their relative engineering properties. Tests were per- <br />formed in accordance with test methods of the American Society <br />for Testing and Materials or other accepted standards. The <br />triaxial shear test was performed at three load points by the <br />Stress Path method. The results of our laboratory tests are <br />included in this report. The in-place moisture content and the <br />standard penetration test values are presented on the attached <br />drilling logs. <br />The in-place density of typical spoils material was measured by <br />three random direct transmission measurements with a nuclear <br />density/moisture gauge. A sample of spoils material was returned <br />to the laboratory to perform a Standard Proctor test which, in <br />effect, establishes the 100$ compaction point of the soil under <br />the compactive energy set forth for a standard test. <br />Findings <br />The measurements for the location of the proposed spoils is shown <br />on the attached site profile. This same set of data was entered <br />in the computer program to locate the surfaces required for <br />calculation. These surfaces basically consist of the exposed <br />surface--which is partially assumed in the spoils area, the bot- <br />tom surface of the spoils and the top surface of bedrock. <br />The bedrock was examined where exposed, and was found to consist <br />of interbedded sandstone and claystone in the location of the <br />proposed spoil deposit. At the toe of the slope at the level of <br />the service road, the exposed bedrock was found to be dense <br />claystone. In both cases, weathering is minor and the bedrock <br />was found to be sufficiently strong to support the existing and <br />the proposed spoils piles. <br />The spoil materal was found to have a maximum Standard Proctor <br />density and optimum moisture content of 91.8 pcf at 17.78. In- <br />place density tests performed on the site showed that the <br />material in place was variable in density, ranging from 69.98 at <br />a moisture content of 26.28, to 82.18 at a moisture content of <br />19.4$. This translates to an in-place density ranging from <br />81 pcf to 90.9 pcf wet density, with an average wet density of <br />87.3 pcf. <br />