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LM <br /> LEED5HILL HEAKENHOFF INC <br /> September 1990 <br /> INTRODUCTION <br /> The following report summarizes Leedsh�ll_ <br /> Herkenhoff, Inc 's (LH) ongoing site <br /> ' investigation at 102 South Wilson Way, Stockton The site was formerly occupied by a <br /> gasoline station until 1978, when all tanks and appurtenances were removed <br /> An initial site assessment was conducted by Balbi & Chang Associates, Inc (BCA) in April <br /> of 1988 without contacting or obtaining appropriate permits from the San Joaquin County <br /> Public Health Services Consequently, the initial site assessment had to be repeated and <br /> ' the results were presented in a BCA report dated April 26, 1989. In RCA's studies, four <br /> soil borings and three monitoring wells were installed. The April 1989 report indicated <br /> some detectable BTX&E (benzene, toluene, xylene and ethylbenzene) and TPH (total <br /> petroleum hydrocarbons as gasoline) in the soil and groundwater samples but the final <br /> conclusions contained conflicting information. <br /> In June of 1989, LH was contracted by the professional corporation of Neumdler & <br /> Beardslee and requested to conduct an additional site investigation to verify the presence <br /> or absence of soil and/or groundwater contamination and, if necessary, provide <br /> information regarding the vertical and lateral extent of such contamination <br /> In January of 1990, LH submitted a Preliminary Investigation Report which documented <br /> LH's investigation. This investigabon verified the existence of petroleum hydrocarbon <br /> contamination in the groundwater, but did not identify a current on-site source of this <br /> contamination from the areas investigated Soil Boring T135 indicated petroleum <br /> hydrocarbon contamination in the sod to a depth of 30 feet, but contained no detectable <br /> hydrocarbons below that depth_ <br /> In August 1990, as a part of its ongoing investigation, LH installed three additional soil <br /> borings near T135 located in the northwest corner of the site, in an attempt to determine <br /> the areal and vertical extent of soil contamination. One of these three borings was then <br /> converted into a 73-foot deep monitoring well to replace the nearby MW1, which has <br /> gone dry. This report presents the findings and conclusions of this supplemental <br /> investigation. <br /> 1 <br /> f <br /> 9 <br />