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SHANNON 6WILSON,INC. <br /> If the location of the bulkhead is moved, different water levels are assumed, steeper <br /> slopes are used, or multiple anchor levels are considered, and the lateral earth pressures shown in <br /> Figures 5 and 6 would not be applicable and should be revised. As discussed in Section 4.1.1, <br /> liquefaction potential in the Segment D area is predicted to be higher, based on boring B-1 B. <br /> Therefore, if a similar bulkhead design is desired for Segment D, we recommend performing <br /> additional explorations and laboratory testing to evaluate the liquefaction potential of the fill and <br /> alluvial soils in this area. if the additional borings indicate minimal and localized liquefaction <br /> under the 200-year.design ground motion, then the earth pressures shown in Figure 6 would be <br /> applicable. <br /> The passive earth pressure diagrams shown in the figures are based on ultimate values. <br /> To obtain allowable values, we recommend that the passive earth pressure values be divided by <br /> 1.5 for static conditions or 1.0 for seismic conditions. Alternatively,the ultimate passive earth <br /> pressures can be adjusted based on allowable displacement by using mobilization factors <br /> provided in Figure 7. <br /> 4.2.2 Deadman <br /> A single row of deadman anchors is proposed as part of the bulkhead design. <br /> Recommended lateral earth pressures for the design of the deadman anchors are provided in <br /> Figure 8. Lateral earth pressures will depend on the type of soil that is present in front of the <br /> deadman anchor. If the deadman anchor is constructed in a shored excavation that is not bigger <br /> than the anchor,then the anchor would react against in situ soil, which is uncompacted fill and <br /> alluvial soil. To improve the resistance of the deadman anchor, the in situ soil in front of the <br /> anchor could be removed and replaced with compacted structural fill. The required dimensions <br /> of this replacement are shown in Figure 8. The passive resistance values shown in the figure are <br /> ultimate values. To obtain allowable values, we recommend that the passive earth pressure <br /> values be divided by 1.5 for static conditions or 1.0 for seismic conditions. Alternatively, the <br /> Ultimate passive earth pressure can be adjusted based on allowable displacement by using <br /> mobilization factors provided in Figure 7, as discussed above. <br /> 4.3 Evaluation of Temporary Dredged Condition <br /> Temporary dredging is planned along areas of the existing bulkhead to remove contaminated <br /> sediments. The 90 percent design drawings by Landau indicate that the extent of dredging <br /> varies, and that it will be performed concurrently with the construction of the new bulkheads. At <br /> Segments A and B soil will be dredge to elevation -14 feet with no slope in front of the bulkhead. <br /> 21-1-21761-003-R I f.doca/wp/cIp 21-1-21761-003 <br /> 12 <br />