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v 0 A S S O C I A T E S I N C did not contain detectable concentrations of BTEX The grab groundwater sample from boring S138 also contained trace concentrations of total lead None of the grab groundwater samples collected contained detectable concentrations of oxygenate fuel additives Analytical results of groundwater samples are summarized in Table 2 Laboratory data sheets and chatn-of-custody documentation for groundwater samples are contained in Appendix C ' 5.0 WELL SURVEY ' ATC performed a well survey for the site at the request of PHS/EHD ATC reviewed PHS/EHD groundwater well construction logs, Department of Water Resources (DWR) groundwater well construction logs, conducted a site walk in the vicinity of the site, and contacted the City of Ripon ' Public Works Department to identify any groundwater wells located within 2,000-foot radius of the site The search revealed nineteen wells located in the vicinity of the site and sixteen of these wells are within approximately 2,000 feet of the site Only one of the sixteen wells is located within 500 feet of the site The well locations are shown on Figure 3 ' The wells were located on the map according to "well location" description information provided on the well construction logs Available well construction logs are contained in Appendix D Based on ATC's current work at a project located approximately one-half mile southeast of the site, the inferred regional groundwater gradient is to the northeast The well located southeast of the football field at Ripon High School (Well No 18) is the closest ' to the site (within approximately 500 feet west-southwest) According to the well data sheet provided by Ripon Unified School District, the well is approximately 149 feet deep and supplies drinking water to the high school The screen interval is unknown, but the groundwater pump in ' the well is located at approximately 42 feet bgs Because this well is located upgradient from the site, it is ATC's judgment that it is unlikely that the well has been impacted by petroleum hydrocarbons from the site The well located on the southeast corner of Ridge Avenue and Washington Street (Well No 1 1) is the closest downgradient well to the site (within approximately 1,000 feet northeast of the site) ' According to the log, the well is approximately 212 feet deep and is screened from 192 feet to 212 feet bgs Because of its distance from the site and the fact that the well is screened at a very deep interval, it is ATC's judgment that it is unlikely that this well has been impacted by ' petroleum hydrocarbons from the site ' 6.0 CONCLUSIONS Based on the analytical results and field observations, the soil and groundwater southeast of the ' location of the former USTs and fuel dispenser are impacted by petroleum hydrocarbons The horizontal extent of the impacted soil and groundwater has been defined to the north, west, and east and an isoconcentration map showing TPHg concentrations in the groundwater is contained in Figure 4 w 113099Vcportslsum2 doc 4