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to the embankment. A conservative seismic coefficient of 0.159 <br />• was selected for use in the stability analyses as noted in <br />Section D.1 of this report. <br />D.6.8.2.2 Materials Properties <br />The tailings disposal area will utilize earthfill <br />embankments and seepage control structures constructed from <br />suitable native materials. Test pit and borehole exploration <br />indicate three broad soil deposits exist as shallow subsurface <br />formations within the outline of the disposal area. These soil <br />deposits are primarily alluvial/colluvial in origin, and <br />despite evidence of interstratification, the deposits appear <br />segregated gradationally to some extent. The regional <br />segregation of these soil deposits will provide borrow areas <br />where fill materials having specific geotechnical properties <br />may be systematically excavated during construction operations. <br />• Surface grading of the disposal area floor will result <br />in the excavation of over two million cubic yards of <br />construction materials. The properties of the materials are <br />summarized on Table D.6-2. <br />D.6.8.2.3 D~sian Parameters <br />The material property parameters used in the analyses <br />were based on laboratory test results contained in Appendix <br />A, Field Data, and acceptable correlations presented in the <br />literature. The tailings were assumed to behave as a low- <br />strength cohesionless soil resting on the upstream face. A <br />summary of the parameters is presented on Table D.6-3. <br />D.6.8.2.4 Stability Analysis Results and Conclusions <br />The results of the stability analyses performed indicate <br />. that the main embankment will be stable under each of the <br />D-66 <br />