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• A layer of weathered claystone materials was encountered below the existing fill materials or natural clays in <br />all of the test holes and three of the test pits. The layers of weathered claystone materials generally ranged <br />from 2 to 12 feet in thickness. The weathered claystone materials were nil to sandy, low to highly plastic, <br />blocky and highly fractured, moist to wet and light brown to gray in color. Samples of the weathered claystone <br />materials generally classified as a CL to CL-CH soils in accordance with the Unified Soil Classification <br />System. <br />Claystone bedrock was encountered below the weathered claystone materials at depths ranging from 13 to 33 <br />feet beneath the existing ground surface in the slide area and at depths ranging from 5 to over 35 feet beneath <br />the existing ground surface in the area situated east of the slide area. The claystone bedrock materials were nil <br />to slightly sandy, moderately to highly plastic, hard to very hard, slightly moist to moist and light gray to dark <br />gray in color. The claystone bedrock materials generally classified as CL to CH-CL soils in accordance with <br />the Unified Soil Classification System. Based on the depth to bedrock in the test holes drilled across the site, <br />an interpreted Bedrock Surface Contour Map was prepared and is shown in Figure # S. The Bedrock Surface <br />Contour Map generally indicates that the bedrock surface is dipping down to the west-southwest in the failure <br />area. <br />The unconfined-compressive strength test results indicate that the clay fill materials and natural clays that were <br />tested exhibited unconfined-compressive strength values ranging from 1,000 to 3,100 psf. The weathered <br />claystone materials that were tested exhibited unconfined-compressive strength values ranging from 4,000 psf <br />to 5,000 psf. Whereas, the claystone bedrock materials that were tested exhibited unconfined-compressive <br />strength values ranging from 6,400 psf to 9,100 psf. The laboratory test results, including the unconfined- <br />compressive strength test values, are shown in Table 1. <br />Free groundwater was encountered in all of the test holes that were drilled within the slide area and to the east <br />and uphill of the slide at the time of drilling, as well as in two of the test pits. It should be noted that due to the <br />caving of the fill materials and the excessive groundwater flows the test pits could not be excavated into the <br />underlying competent bedrock materials. <br />The only test hole where groundwater was not encountered either at the time of drilling or when measured 38 <br />days after the drilling was completed was in Test Hole 11, which was drilled outside of the slide area and to <br />the southeast of Pond 16A. <br />As noted previously, nine of the test holes were cased with slotted and solid 2-inch diameter PVC pipe so that <br />groundwater levels and soil movements could be monitored after the drilling was completed. NWCC, Inc. <br />visited the site a number of times in the last ten months to measure and record the groundwater levels in the <br />monitor wells, as well as evaluate the ground movement in the test hole locations. The groundwater levels <br />0 Job Number: 08-8099 NWCC, Inc. Page 6 <br />