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WN i.# <br /> d <br /> o w• <br /> found at 0.06 ug/ml and total lead was less thall .01 m91k9m. <br /> The water samples taken from and 1.111-3 also had <br /> concentrations al>ove the defection limits for the parameters <br /> tested including benzene, toluene, xylene, total g;:�solire <br /> hydrocarbons, rig and total lead (See Apper,di% C) . <br /> Eased on the sa:,.,pling efforts and the chemical analysis <br /> results, the area below and adjacent to the tank rer.oval area <br /> has fuel related compounds significantly above the detection <br /> limits for the compounds tested. The soil samples taken helot.: <br /> the tank removal area (KW-4) contained higher concentrations <br /> than other borings surrounding the removal area. The condition <br /> of the 704 gasoline tank removed from the site appeared to be <br /> old and contained many "pin" holes. Based on the condition of <br /> the tank and the analytical results of the soils beneath it, we <br /> conclude that the underground storage tank may have allowed <br /> releases of product into the soil. <br /> The groundwater contained in the uppermost aquifer, at an <br /> average depth of 13 to 14 feet, also contained appreciable <br /> amounts of fuel-related compounds. The largest concentrations <br /> -1 andep ri in water were received in monitoring wells Wand subsel�l-2 <br /> These two wells, from the well elevation survey quent <br /> groundwater surface measurements, are considered to be <br /> upgradient from the tank removal area. That is, groundwater <br /> flow according to the measurements we have to date, is from the <br /> southeast towards the northwest. Therefore, the possibility <br /> exists that there is an off-site source moving through <br /> groundwater onto the Manteca Bean Company site. There could <br /> also be complicated groundwater flow variations due to seasonal <br /> changes or local pumping or recharge of the uppermost shallow <br /> water-bearing zone. Additional data is needed to make a <br /> determination of groundwater flow parameters in the area. <br /> V. RECOMMENDATIONS <br /> In order to evaluate the approximate extent of fu3l-related <br /> compounds on the Manteca Bean Co. site, the following tasks are <br /> proposed: <br /> 1. Monitor the water levels in the existing wells once a week <br /> for a period of b to 8 weeks to establish a more precise <br /> indication of the groundwater flow gradient and direction <br /> beneath the site. <br /> 2. Install four additional borings/wells to better <br /> characterize the extent of contamination and gather <br /> ._r additional data concerning groundwater flow <br /> 4 <br /> D <br />