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Emma. <br /> CZEMESM <br /> Mr James Barton <br />' July 30, 2004 <br /> Page 3 <br />' lateral extent of hydrocarbon-impacted groundwater In May 2002, the RIW was replaced The <br /> new Delta College irrigation well became operational in July 2002 <br />' Site Geology <br /> Site stratigraphy is generally segregated into four hydro-stratigraphic units The shallowest <br />' wells are screened across the hydro-stratigraphic unit designated as Unit A and the deepest <br /> wells are screened across the hydro-stratigraphic unit designated as Unit D Although four <br /> groundwater zones have been designated by Environmental Audit Incorporated (EAI), the water <br /> table elevation data and subsurface lithology reported on boring logs do not appear to support <br />' the existence of more than one distinct hydro-stratigraphic unit The approximate depth <br /> intervals corresponding to the hydro-stratigraphlic units, as defined by EAI are as follows <br />' Hydra-Stratigraph ic Unit Depth Interval (feet bgs) <br /> A 30-50 <br /> B 50-70 <br /> C 85-90 <br /> D 97-103 <br /> Unit A wells include MW-10A, MW-14A, MW-18, MW-19S, MW-21S, MW-22S, and MW-25S <br />' and are screened from approximately 30 to 50 feet below grade surface (bgs) Unit B wells <br /> include MW-1 through MW-7, MW-9 through MW-17, MW-18D, MW-19D, MW-21 D, MW-22D, <br /> MW-25D, AS-26, and MW-27 and are screened from approximately 50 to 70 feet bgs Unit C <br />' wells include MW-23S and MW-24S and are screened from approximately 85 to 90 feet bgs <br /> Unit D wells include MW-8D, MW-23D, and MW-24D and are screened from approximately 97 <br /> to 103 feet bgs <br />' Soil beneath the site consists of clayey and sandy silt from the surface to approximately 40 to <br /> 45 feet The silts are underlain by a layer of fine to coarse sand from approximately 45 to 60 feet <br />' bgs This sand layer contains thin layers of silty clay approximately 6-inches thick The sand <br /> layer is underlain by clayey silt and silty clay to the total depth explored of approximately <br /> 103 feet bgs Geologic cross-sections depicting subsurface conditions have been prepared for <br /> the site A geologic cross section location map is presented as Figure 3 and cross-sections <br /> eA-A', B-B', and C-C' are included as Figure 4 through Figure 6 <br /> Permits <br /> Well permits were obtained from San Joaquin County Environmental Health Department <br /> (SJCEHD) Copies of the permits are included in Attachment B <br /> J 1Protects10 MM5098 293TinaAReportsti5098 Well Results Report doc <br />' )vp 3r, Year;of wxrPReitce in Eavucmnenral Service,, <br />