Laserfiche WebLink
3.0 GEOLOGY AND HYDROGEOLOGY <br /> ' 3. 1 GEOLOGY <br /> ' The North County Sanitary Landfill is located near the northeastern <br /> edge of the San Joaquin Valley. The valley is a deep, asymmetric <br /> structural trough filled with sediments derived from adjacent mountain <br /> ranges. The geology of the eastern portion of the San Joaquin Valley <br /> ' is characterized by alluvial sediments deposited by rivers and streams <br /> emanating from source terrains in the Sierra Nevada Mountains to the <br /> east. <br /> The youngest geologic units underlying the site are semi consol i dated <br /> ' alluvial deposits of the Turlock Lake and Riverbank Formations. These <br /> two formations consist of heterogeneous deposits of gravels, sands, <br /> silts, and clays. Because of similar origins and common lithologies, <br /> differentiation of alluvial deposits into formations is difficult. <br /> Regionally, lateral and vertical lithologic variations within a <br /> formation can be pronounced. <br /> ' The geologic units beneath the site were characterized by reviewing <br /> existing local data and drilling six borings ranging from 40.5 to <br /> 215 feet in depth (see Appendix A, Geologic and Hydrogeologic Report) . <br /> In addition to the borings drilled by EMCON, previous drilling was <br /> ' conducted by another consultant on the same property and on the half- <br /> section parcel immediately to the west. Data from these earlier <br /> ' borings were also analyzed in studying the subsurface geology of the <br /> site. <br /> The exploratory drilling performed during this and previous investiga- <br /> tions confirmed that subsurface conditions are consistent with the <br /> ' regional information described above. Borings penetrated interlayered <br /> silts, clay, and fine sand to their entire depths. Finer-grained <br /> materials (silt, clay, and silty sand) predominate. Boring logs are <br /> contained in Appendix A. <br /> ' PJ9 9390209A.00D 7 <br /> Emon Associates <br />