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W. MICHAEL CARROLL, PE COUNTY OF SAN JOAQUIN DEPARTMENT OF PUBLIC WORKS DECEMBER 22, 2009 and were sheared at a rate of 0.04 inch/minute. Each test was either soaked at the testing normal stress for 72 hours or soaked at a reduced normal stress (0 to 1440 psf) for at least 24 hours and consolidated. These are conservative or comparable hydration conditions compared to those specified in Table 1, where specimens are specified to hydrate at the testing normal stress for 48 hours. The failure plane, in all cases, Was not internal to the GCL. As previously discussed, we will modify the GCL specifications for all future modules to attempt to avoid internal GCL failure. The specifications will continue to require the shear strengths shown in Table 1 based on a friction angle of 12 degrees. Note interface shear strength testing of liner materials during constriction for all future modules (5 through 11) will be up to a maximum normal stress of 20,000 psf as stated in Section 9.2.1 of Appendix E. Technical specifications that will be developed for construction of each module will mimic these requirements. If any test results during module construction fall below the values assumed in Appendix E or this analysis, the affected sections will be re -analyzed. As is typical, the RWQCB will be kept apprised of construction activities and any variances from the approved design. Note 2 of Appendix E, Geotechnical Analyses for the Vertical Expansion of North County Recycling Center and Sanitary Landfill, indicates a friction angle of 13 degrees. I believe this should be 12 degrees. Agreed: Note 2 of Table 3 in Appendix E should read 12 degrees. This is a misprint. The required large - displacement shear strengths in Table 3 are based on a friction angle of 12 degrees. A revised Table 3 is attached. 0 Seismic Hazard Report Attachment C of Appendix E, Geotechnical Analyses for the Vertical Expansion of North County Recycling Center and Sanitary Landfill, contains the estimate of the MPE ground motions for the North County Site by Dr. Norman Abrahamson dated June 18, 2007. Based on the known faults in the area, the estimated peak ground acceleration for the site is low. Values of peak acceleration are 0.1g and 0.098 for the CRCV and San Andreas Fault systems, respectively. As a check, DWR staff performed some simplified probabilistic analyses for the site using the USGS website. DWR staff recommends that some simplified deformation analyses be performed for the landfill using the Makdisi Seed method (1977) or Computer Program Displace. DWR staff feels that Dr. Abrahamson's findings are accurate given the known faults and MPE loading assumed. DWR staff, however, recommends that consideration be given to increasing the design earthquake loading to 0.15g. DWR feels this increase is warranted given the height of the embankment, the results of the simplified USGS analyses performed by DWR, and the possibility that a small earthquake, such as a M 5.5 or 6, can occur almost anywhere in California. The Makdisi Seed method evaluates deformation for Magnitude 6.5, 7.5, large 8.5 (Richter) magnitude earthquake events. If the Makdisi-Seed method is performed, the lower bound fault range should be assumed. The yield accelerations for all sections were recalculated based on configuration and material property updates discussed above. Using the yield accelerations from the revised analyses, seismic displacement was calculated using the Makdisi-Seed method using the lower -bound curve for a Magnitude 6.5 PAGE 8