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mp <br /> � gt_ <br /> x_ <br /> i":,m.. . <br /> 10 E I <br /> f <br /> !. H. KLEINFELDER &ASSOCIATES <br /> Ground water flow direction is to the east—southeast with aradi <br /> 1.5 inches g ent of <br /> per 10 ft, Locations of monitoring welis were based on <br /> regional ground water maps for the Stockton area and on recommendations <br /> from San Joaquin county which indicated ground water flow to be to the " <br /> north. Localized conditions at this site have apparently resulted in an <br /> eastward clow direction. The cause of <br /> the eastward flow direction is not <br /> 3 known at this time, but may be a result ofin um b <br /> Canning Plant which is situated east of the TeiP P g Y the Del Monte <br /> chert facility. Apparent <br /> ground water flow direction and gradient are presented on Plate 3. <br /> 5.3 NATURE AND EXTENT OF SOIL AND GROUND WATF.H CONTAMINATION <br /> {3 <br /> The. vertical and areal distribution of gasoline and its key constituents <br /> in soil are displayed on Plates 27 through 45 and Plates 46 through 49. <br /> These are non—biased computer <br /> generated contours based on the analytical - <br /> 3:a results. A zero value (non—detect) was arbitrarily applied at soil boring <br /> locations and at depth intervals where PID readings indicated the area was <br /> _ not affected by the leakage to establish a realistic boundary condition. <br /> Without this bounder <br /> y condition, contour lines could be extended to <br /> infinity. <br /> ,.a <br /> The data and computer analyses show contamination spread to form an oblong <br /> pear—shaped plume. When the vertical chemical concentration profile is <br /> everlayed across the geological cross—section, an influence of the soil <br /> type and geology on the distribution of the hydrocarbons is displayed, <br /> K ° particularly for the aromatic species.P The silt layer occurring from <br /> r between 20 and 30 ft below land surface and extending to ground water <br /> appears to have retarded its migration and influenced its distribution <br /> pattern. <br /> Eel <br /> A mass calculation was performed to <br /> ( t eR4imate the volume of gasoline <br /> present at the four depth intervals and throughout the affected area. The <br /> a,. <br /> mass of gasoline was estimated using the following procedures: <br /> o A 1planimeter was used to estimate the area beCween each affected T <br /> i <br /> contuur` intervals at each of the four depths. <br /> d: - <br /> 38-87-43 <br /> 13 <br />