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Claystone bedrock was encountered beneath the clays in all of the test holes and extended to the maximum <br />• depth investigated in each test hole. The claystone bedrock materials were nil to slightly sandy, moderately <br />to highly plastic, hard to very hard, dry to slightly moist with rust staining and calcareous stringers. <br />Samples of the claystone bedrock materials classified as CL-CH and CL soils in accordance with the <br />Unified Soil Classification System. <br />Swell-consolidation tests conducted on samples of the natural clays and claystone bedrock materials <br />indicate that the materials tested will exhibit a high to very high swell potential when wetted under a <br />constant load. The swell-consolidation test results are shown in Figures #5 through #8. <br />Unconfined compressive strength tests conducted on in-situ samples of the natural clays indicate that these <br />materials exhibited compressive strength values ranging from 6,200 to 25,200 psf; whereas, the unconfined <br />compressive strength test conducted on a remolded sample of the clays exhibited a compressive strength <br />value of 3,900 psf. The unconfined compressive strength test conducted on an in-situ sample of the natural <br />claystone bedrock materials indicates that the undisturbed bedrock sample exhibited a compressive strength <br />value of 47,000 psf; whereas, the unconfined compressive strength test conducted on a remolded sample of <br />the claystone bedrock materials exhibited a compressive strength value of 8,100 psf. <br />The falling head permeability tests conducted on samples of the in-situ natural clays, as well as remolded <br />samples of the clays and claystone bedrock materials indicate that these materials exhibited a very low <br />permeability with coefficients on the order of 1.2 x 10-7 to 5.3 x 10-9 centimeters/second (cm/sec). The <br />permeability test results are provided in Appendix A. <br />Free groundwater was not encountered in any of the test holes at the time of drilling. It should be noted that <br />groundwater conditions can be expected to fluctuate with changes in precipitation, and runoff. <br />Foundation Recommendations <br />Based on the subsurface conditions encountered in the test holes, the results of the field and laboratory <br />investigations, our understanding of the proposed construction, we believe an economically feasible and <br />safe type of foundation system for any building or equipment structures constructed at the site is straight- <br />shaft skin friction/end bearing piers drilled into the underlying claystone bedrock. Foundation movement <br />should be within tolerable limits if the following design and construction precautions are observed. <br />1) A minimum pier diameter of 12 inches, a minimum pier length of 20 feet and a minimum bedrock <br />penetration of 6 feet are recommended. A maximum pier length to diameter ratio of 25 should be <br />used in the pier design. <br />• <br />Job Number: 08-8241 NWCC, Inc. Page 4