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• a walking survey of the area within a few blocks of the site The purpose of these activities was <br /> to locate any municipal or domestic wells, utility trenches, surface water bodies, or other features <br /> that could serve as receptors or conduits for contaminants that could potentially migrate from the <br /> site <br /> Table 5 shows the list of wells that were recorded in the DWR files, and Figure 4 shows their <br /> map location There are four wells within approximately 2000 feet of the site The California <br /> Water Service operates a municipal drinking water well that is located approximately 1850 feet <br /> north of the site, near the intersection of Lindsay and Aurora Streets The well is perforated in a <br /> deeper aquifer than has been impacted at the Valley Motors site, and is not likely to be impacted <br /> by the contamination at Valley Motors The other three wells are all located to the west of the <br /> site, in the upgradient direction Therefore, none of these wells is threatened <br /> i <br /> The walking tour of the area focused on the three blocks just east of the site This area is <br /> downgradient of Valley Motors, and is the most likely to be impacted by subsurface groundwater <br /> flow The area is occupied by a mixture of commercial, industrial, and residential properties, and <br /> is transected by two railroads (the former Southern Pacific and Western Pacific main lines) <br /> Many of the commercial properties are abandoned and boarded up, and the area is suffering from <br /> economic blight Some of the residential units are poorly maintained, while others are inhabited <br /> and in better condition All of the buildings appear to be on City water supplies, as no domestic <br /> wells were observed No surface water bodies were observed There are numerous subsurface <br /> utility lines (sewer, storm drains, water, etc ) along most streets These are the only features that <br /> could serve as conduits for groundwater flow, however, because the minimum depth to <br /> groundwater has been about 30 feet, none of these utility lines could have been impacted by <br /> contaminants emanating from Valley Motors <br /> 6.0 CONCLUSIONS AND RECOMMENDATIONS <br /> The data obtained from the wells that were drilled in August imply that soil contamination is <br /> even more limited in extent than previously thought Hydrocarbon concentrations in the air <br /> sparging well were less than expected, and no hydrocarbons at all were detected in the vapor <br /> extraction well We recommend testing these wells when the groundwater begins to rise again <br /> during the 1st quarter of 2000, to estimate their effectiveness in remediating the site We also <br /> recommend conducting the groundwater pumping test in early 2000 <br /> Hydrocarbon concentrations continue to fluctuate in groundwater samples, and the reasons are <br /> not clearly apparent Now that contaminants have been detected in both VM-3 and VM-4, the <br /> eastern limit of groundwater contamination is no longer certain Monitoring should continue so <br /> that trends in hydrocarbon concentrations can be tracked The next monitoring event is scheduled <br /> for late December, 1999 <br /> Gasoline oxygenates are not a contaminant at this site We recommend discontinuing analysis for <br /> • oxygenates, methanol, and ethanol <br /> 6 <br />