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CONDOR EARTH TECHNOLOGIES, INC. 188 Frank West Circle, Suite I Stockton, CA 95206 Phone 209.234.0518 Fax 209.234.0538 CONDORwww.condorearth.com November 4, 2015 Jennifer Thornburg and Will Harris California Geological Survey School Review Unit 801 K Street MS 12-31 Sacramento CA 95814 Subject: Revised Analysis and Recommendations Based On Engineering Geology and Seismology Review for Lincoln Elementary School-Cafeteria/Administration Building 750 E. Yosemite Avenue, Manteca, California, Dated November 3, 2015 CGS Application No. 02 -CGS 1997 Condor Project No. 6999B Dear Ms. Thornburg and Mr. Harris: This letter provides revised analysis and recommendations pursuant to the comments received in your Engineering and Seismology Review letter, dated November 3, 2015, with respect to the report titled Geotechnical Engineering and Geological Hazard Study, Lincoln Elementary School Modernization, 750 E. Yosemite Avenue, Manteca, California, " dated May 19, 2015. This letter is prepared on behalf of Manteca Unified School District. Condor recognizes that some strata are marginal with regard to site classification. Our calculations of the average blow count of 17 (pg 7) were based on the methodology included in the 2013 CBC for B-1 and B-8 over the 51.5 feet explored and tested. In addition we recognized that the clay strata were stiff. Therefore, the classification of Site Class E "soft clay" was not used based on our blow count data and review of the cohesive strengths of the clay strata. Soft clays typically have an N -value of 2-4. Based on your suggestion that the materials should be a Site Class E, we reviewed the data. The medium stiff to stiff silts can be transitional, and blow counts are difficult to correlate to cohesive values or relative density in these materials. We also reviewed the resulting seismic design parameters with both the Site Class D and E values. The change in results is modest, and we are therefore comfortable using the Site Class E and providing revised seismic parameters. We also reevaluated our previous liquefaction analysis for B-1 based on the revised Site Class. Therefore, Section 6.1 GROUND SHAKING should be amended as: Site Class E is appropriate for this site. Section 6.1.1 Design Parameters for Seismic Shaking should be amended as: We recommend the following values for structural design according to the 2013 CBC and USGS. These values are based on PGA= 0.354; PGAM- 0.367; Ss = 0.970; S, = 0.348; Fa t 0.935; and Fv = 2.608.