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<br />Mr. Timm Comer <br />Manager, Environmental Resources ame <br />ADR Water Line <br />January 3, 2010 <br />For the broken water pipelines scenario, a piezometric surface representing the conditions <br />presented in Figure 1 (largest saturated section) was used. As shown in Figure 5, the FOS <br />drops slightly to 1.7, which is still above the minimum FOS of 1.5, set forth in the Design Criteria <br />for the VLF. <br />tni?:, Far>r <br />J,! <br />a, <br />a.: <br />r. <br />8 <br />0 <br />Material Properties <br />Material: Foundation <br />Strength Type: Mohr-Coulomb <br />Unit Weight: 150lbttt3 <br />Cohesion: l psl <br />Friction Angle: 40 degrees <br />Water Surface: None <br />Material: Structural Fill <br />Strength Type: Mohr-Coulomb <br />Unsaturated Unit Weight: 1201b1 t3 <br />Saturated Unit Weight: 12511:40 <br />Cohosion:I pat <br />Friction Angle: 38 degrees <br />Water Surface: None <br />•150 •100 •50 0 50 100 •.150 200 250 300 350 400 <br />Figure 5 Saturated PSSA Embankment Stability <br />Conclusions <br />The results of the seepage and stability analyses indicate that if the ADR water pipelines were <br />to fail, only a small proportion of the structural fill would become saturated, even after 15 days. <br />The majority of the water would express itself at the surface of the PSSA embankment, as the <br />hydraulic pressure head within the pipelines is greater than the level of confinement at a depth <br />of 5 feet. <br />The results from the stability analyses, under the worst-case scenario (e.g. largest saturated <br />section), indicate the PSSA embankment would still maintain a Factor of Safety greater than the <br />minimum acceptable level of 1.5. <br />MACINTOSH HD:USERS:JLUPO:D000MENTS:CC&V:WATER LINE lettecdoc 5