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LEEDSHlLL•HERKENHOFF, INC. <br /> 303 Second Street. Sidle sw Nortf, <br /> s a San Francisco, California 94107 D <br /> 4151243.OW <br /> 12 November 1990 <br /> Deanne M. Zoiezzi <br /> Neumiiier b Beardslee <br /> P.O. Drawer 20 <br /> Stockton, CA 95201-3020 <br /> Re: Weber Point, 141 North El Dorado Street, Stockton <br /> Dear Ms. Zolezzi : <br /> Enclosed is a copy of a preliminary site assessment report prepared by Leedshill - <br /> Herkenhoff, Inc. (LH) for the Weber property located at 141 North El Dorado <br /> Street in Stockton, California. The purpose of this investigation was to <br /> determine the presence or absence of petroleum hydrocarbon contamination in the <br /> soils and/or groundwater beneath the property and, if present, attempt to <br /> estimate the lateral and/or vertical extent of contamination. <br /> In September 1990, eight soil borings were initially installed to determine the <br /> presence or absence of soil contamination at the site. Significant soil <br /> contamination was found within the former underground storage tank (UST) <br /> excavation to depths which indicated that the groundwater may have been impacted. <br /> Therefore, three additional soil borings were installed around the former <br /> excavation for subsequent conversion to monitoring wells to further define the <br /> lateral and vertical extent of soil contamination and determine the presence or <br /> absence of groundwater contamination. <br /> Laboratory analysis of soil samples obtained from the soil borings described <br /> above indicates that soil contamination exists in the center (soil boring SB3) <br /> and on the eastern side (soil boring S84) of the former UST excavation to a depth <br /> of at least 36.5 feet. Laboratory analysis of soil samples obtained from <br /> monitoring well MW2 indicates that some of this contamination may have migrated <br /> laterally off-site in a northerly direction within a sand layer located at a <br /> depth of approximately 16.5 feet. Soil samples obtained from the other soil <br /> borings on the site indicate very low or non-detectable concentrations of <br /> petroleum hydrocarbons. <br /> As discussed above, three of the soil borings were subsequently converted into <br /> monitoring wells. Laboratory analysis of representative groundwater samples <br /> collected from these wells indicates that the groundwater is contaminated. <br /> Monitoring well MW3, which is the down gradient well , has the highest <br /> concentration of petroleum hydrocarbons indicating that the source of the <br /> contamination may be the former ust excavation. <br /> f <br /> SAN FRANCISCO SAN DIEGO DENVER ALBUQUERQUE SANTA FE PHOENIX <br />