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0 • <br /> January 25, 2016 Monitoring Well Abandonment Workplan <br /> deposits are derived from a mixture of Sierra Nevada and Coast Range rocks'.The near surface <br /> deposits are mapped primarily as Quaternary alluvial flood plain deposits¢.The local depositional <br /> environment is a sedimentary river basin,and the shallow sediments are primarily flood plain and <br /> over bank deposits of sand,silt and clay.The near surface deposits are characterized by <br /> discontinuous inter-bedded silty sand,sandy silt,silty clay,clay,and sand depositss. Soils are <br /> derived from mixed Sierra and Coast Range source materials,and are characterized by poor <br /> drainage6. <br /> The Lathrop area groundwater basin is comprised of an approximately 150-feet thick upper water- <br /> bearing zone overlying a 75 to 1,000 feet thick lower water-bearing zone.The lower water-bearing <br /> zone provides drinking water to the City of Lathrop.The hydraulic connection between the upper <br /> and lower zones appears limited due to extensive low permeability strata.? <br /> Depth to groundwater varies depending on location,season,and local influences.The shallowest <br /> groundwater levels are generally observed adjacent to the San Joaquin River,and groundwater <br /> depths tend to increase with distance from the river.In the alluvial flood plain deposits, <br /> groundwater is typically within 12 feet of land surface. <br /> 1.3. Proposed Monitoring Well Abandonment <br /> Ten monitoring wells are recommended for abandonment(see Table 1 for monitoring well <br /> construction information).Appendix Al contains their well construction permits and Appendix <br /> A2 contains their well logs. <br /> AUG 2 5 NIS <br /> �NVIRON��R NtENT <br /> N�.RI'CH DE <br /> 'Miller,R.E.,Green,J.H.,Davis,G.H..,1971,U.S.Geological Survey Professional Paper 497-E. <br /> 4 Atwater,B.F.,1982,Geologic maps of the Sacramento-San Joaquin Delta,California,US Geological Survey <br /> Miscellaneous Field Studies Maps,MF-1401. <br /> 5 Kleinfelder,"Hydrogeology of the Mossdale and Reiter Property,Lathrop,California",November 24,2004. <br /> 6 Soil Conservation Service,1992,Soil Survey of San Joaquin County. <br /> 7 Page,R.W., 1985,Geology of the fresh groundwater basin of the Central Valley,California,with texture maps <br /> and sections.U.S.Geological Survey Professional Paper 1401-C. <br /> HydroFocus, Inc. 2 <br />