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Januarv 15, 2008 <br />P(Te 7 <br /> <br /> r7\ <br /> ? <br /> f 4 <br /> <br /> V ?. <br /> / t 1 l <br /> ' <br /> i <br /> -C CK - l ,; <br /> <br /> <br /> <br /> <br /> <br /> <br /> i <br /> ' • 07.OX"CR <br />Figure 3. Projection of Previous Characterization Boreholes 05-G1-CCR through <br />05-G6-CCR to Approximate Location in Landslide <br />Both these weak mudstone layers are known to be highly bedded layers. The slide plane <br />of the landslide is thought to be contained in the weak L-Roof mudstone layer and that plane <br />provides a thin shear plane along the bedding. Direct shear tests are used to characterize rock <br />strength along bedding. Although multiple direct shear tests were not possible from 1.-Roof <br />mudstone samples, one set of' tests were performed on Q-Floor mudstone samples. It is <br />estimated for Table I that the weak mudstones have 20%-50% strength parallel bedding <br />compared to perpendicular to bedding. <br />The test results also suggest that there is significant difference between peak and residual <br />strengths. The residual strengths are about 40% less than measured peak strength values. This <br />can be seen by the stress-strain curve shown in Figure 4. This data is from a sample of the <br />Q-Floor mudstone from borehole 07-G17-CCR at 227 11 below collar. Similarly. there is a <br />diflerence between peak and residual strengths along the bedding, but the reduction is only 20%, <br />less than measured peak strength values. <br />Agapito Associates, Inc.