|
September 30,2015 Monitoring Well Abandonment and
<br /> Installation Workplan
<br /> work plan is also consistent with California Well Standards Bulletin 74-90 and San Joaquin
<br /> County Well Standards.
<br /> 1.3. Local Hydrogeologic Conditions
<br /> The Lathrop area is located in the basin-trough geologic zone of the Sap Joaquin Valley,
<br /> which consists of continental Pleistocene and Holocene stream-laid and still-water
<br /> deposits'.These deposits are derived from a mixture of Sierra Nevada and Coast Range
<br /> rocks2.The near surface deposits are mapped primarily as Quaternary alluvial flood plain
<br /> deposits3.The local depositional environment is a sedimentary river basin,and the shallow
<br /> sediments are primarily flood plain and over bank deposits of sand,silt and clay.The near
<br /> surface deposits are characterized by discontinuous inter-bedded silt sand,sandy silt,silty
<br /> clay,clay,and sand deposits4.Soils are derived from mixed Sierran an Coast Range source
<br /> materials,and are characterized by poor drainages.
<br /> The Lathrop area groundwater basin is comprised of an approximate) 150-feet thick upper
<br /> water-bearing zone overlying a 75 to 1,000 feet thick lower water-being zone.The lower
<br /> water-bearing zone provides drinking water to the City of Lathrop.Th hydraulic
<br /> connection between the upper and lower zones appears limited due textensive low
<br /> permeability strata.6
<br /> Depth to groundwater varies depending on location,season,and local iinfluences.The
<br /> shallowest groundwater levels are generally observed adjacent to the San Joaquin River,
<br /> and groundwater depths tend to increase with distance from the river. In the alluvial flood
<br /> plain deposits,groundwater is typically within 12 feet of land surface.
<br /> 1.4. Proposed Monitoring Well Abandonment
<br /> Monitoring wells KMW-1 (located in LAS-1) and KMW-3 (located in S-2)shall be
<br /> abandoned(see Table 1 for monitoring well construction informatio i).Appendix A
<br /> contains the original well construction permit and Appendix B contains the well logs.
<br /> 3 Jennings,C.W.and Strand, R.G., 1958,"Geologic map of California,Santa Cruz heet",California Division
<br /> of Mines and Geology,Sacramento,California.
<br /> 2 Miller,R.E.,Green,J.H., Davis,G.H..,1971,U.S.Geological Survey Professional Paper 497-E.
<br /> 3 Atwater, B.F., 1982,Geologic maps of the Sacramento-San Joaquin Delta,Calif' rnia, US Geological
<br /> Survey Miscellaneous Field Studies Maps, MF-1401.
<br /> 4 Kleinfelder,"Hydrogeology of the Mossdale and Reiter Property,Lathrop,California",November 24,
<br /> 2004.
<br /> s Soil Conservation Service, 1992,Soil Survey of San Joaquin County.
<br /> c Page, R.W.,1985,Geology of the fresh groundwater basin of the Central Valley,California,with texture
<br /> maps and sections.U.S.Geological Survey Professional Paper 1401-C.
<br /> HydroFocus, Inc. 2
<br />
|