COMPLIANCE INFO_JTD 12/4/2025 - Laserfiche WebLink

Home Browse Search

Foothill Sanitary Landfill Page 12 of 52 San Joaquin County DPW - Solid Waste Joint Technical Document Revised 12/04/2025 preparation for this report was the Concord-Green Valley Fault Zone. The maximum probable earthquake (MPE) magnitudes for the six faults ranged from 6.8 (Green Valley-Concord and Calaveras) to 8.1 (San Andreas). Peak ground acceleration at the site, based on the six nearby faults, ranged from 0.03 g to 0.05 g (Appendix L) Updated Slope Stability Analysis for Foothill Sanitary Landfill, San Joaquin, California dated January of 2012. Please note that estimated values of peak ground acceleration in rock determined from the analysis conducted for this report generally agree with those values established during the preparation of the 2002 report. 4.9. Engineering and Chemical Properties of Soil Soil samples were collected and analyzed by Kleinfelder in 1985 (Appendix D) and 1990 (Appendix E). Laboratory testing included moisture content, unit weight, sieve size/gradation analyses, moisture density, plasticity index, dry density, hydraulic conductivities, and Atterberg Limits. Soil properties are as follows: Dry unit weights of soil samples varied between 73 to 82 pounds per cubic foot Moisture contents ranged from 9 to 41% Plasticity limits ranged from 8 to 29 (PI) Liquid limit of soil ranged from 35 to 45 4.9.1. Stability Analysis Requirements for seismic stability are found in Title 27 Chapter 3 Subchapter 5, addressing requirements for landfill closure. According to Section 21090 of that subchapter, “Designs having any slopes steeper than a horizontal to vertical ratio of three to one, or having a geosynthetic component [under ¶(a)(2)], shall have these aspects of their design specifically supported in the slope stability report required under §21750(f)(5).” Because the final landfill slope configuration is three to one (Figure 6), a stability analysis is required for this site. A stability analysis had been performed previously by EMCON/OWT in 2002 for the overall refuse slope stability of both Modules “I” and 1, and the long-term partial cover of Module “I”. The refuse fill, and cover soils were found to be stable under design conditions (Appendix F). The 2002 EMCON/OWT report discusses the regional geology and site geology as well.