ARCHIVED REPORTS_WELL INSTALLATION AND SOIL AND GROUNDWATER SAMPLING

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' LIGHT, AIR & SPACE CONSTRUCTION ENVIRONMENTAL SERVICES COMPANY ' State Contractor's License Number 445403 State EPA R.E.A.Number 04072 Office 408-979-0661 ' 5.1. 2000-Foot Radius Well Search LA&S performed a 2000-foot radius search for wells around the project site. The search used ' the available information from the State Department of Water Resources tiles to document municipal, domestic, agricultural, industrial and other wells. The information is compiled into a summary table together with a map showing selected well locations within and near search radius (see Figure 1 and Table 2). The mapped well locations are approximate and based upon the information on the individual well log. In some cases the well location, logging and well construction information may not be precise or may be incomplete on the state well completion ' reports. Groundwater monitoring wells installed for regulatory compliance issues are not plotted on this search. ' The well search showed revealed numerous domestic and irrigation wells in the radius clustered near the site area and in the more developed portion of Manteca. Several domestic wells occur near to the site and one domestic drinking water well is used on 19589 McKinley Avenue. A ' brief review of well logs indicates that the depth of the screened intervals of most of these irrigation and domestic wells is below about 75 to 100 feet or deeper and most wells have annular ' sanitary seals of about 20 to 50 feet. Based on this available well screen information, the off- site domestic and irrigation wells in the region appear to be screened below the uppermost aquifer sampled for this study. ' The on-site drinking water well is located inside the small garage next to the residence. No log or well construction information was available for the on-site residence drinking water well and ' no problems have been reported for this well. LA&S collected a sample from this well for chemical analysis and that data is discussed in Section 5.0 below. 5.2 Subsurface Conditions Three exploratory borings were drilled on October 8, 2008 to a maximum depth of 22 feet below the surface. The borings revealed brown to yellow brown sandy silt and silty sand that may be weakly cemented. These strata are underlain by interbedded sandy silt clayey silt, sand and silty sand and appear laterally and vertically discontinuous and compose the uppermost aquifer (see Figure 2 and 3 and Table 1). Groundwater was encountered at depths of about 11 to 12 feet ' below surface grade and appeared to be unconfined. An initial groundwater elevation contour plot indicates a westerly flow direction at a calculated gradient of about 0.003. Please note that groundwater flow directions may be influenced by aquifer recharge and discharge and nearby ' pumping wells. ' January 5 2009 Page 6 of 1z MAIN OFFICE • 1707 LITTLE ORCHARD STREET, SUITE A•SAN JOSE•CA 95125 MAILING ADDRESS•P.O.Box 36303 •SAN JOSE•CA•95158-6303•408/979-0661•408/979-0621 FAX•i.%Su r,s 111\`I 'l f MAI" ' GENERAL AND ENGINEERING CONTRACTOR•HAZARDOUS SUBSTANCE REb1OVAL CONTRACTOR•SITE EiNA'IRONhEIJTAI.ASSESS\IFNs WETLAND AND RIPARIAN HABrrAT-ASSESSMENT-DESIGN-RESTORATION-CONSTRUCTION-MITIGATION MONITORING