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Bank of Stockton - Cutter Lumber Site Page 2 Groundwater Monitoring Well Construction ' Project No 102 2 April 24, 1998 ' hydrocarbons were found in the well water sample Following this discovery, Geological Technics Inc of Modesto, CA conducted a review of public files in ' order to gain a better understanding of the past use of the Property The County Assessor's record for the Property was examined and documentation was found which revealed the existence of the former "Oil Supply" Building and at least one ' associated gasoline UST, several diesel AST's and a dispenser island These facilities were situated 40 to 50 feet from the contaminated domestic water well ' Geological Technics Inc subsequently installed five, 10-foot deep, hand augered j soil borings in the vicinity of the former "Oil Supply" building which revealed the presence of petroleum hydrocarbon impacted soil and what was interpreted to be ' a former gasoline tank pit from which the tank had been removed and the excavation backfilled In March of 1997, Geo-Phase Environmental installed a total of seven soil ' borings which penetrated into the groundwater to provide preliminary information on the extent of hydrocarbon impacted soil in the vadose zone and on the lateral distribution of hydrocarbons in the groundwater The data obtained from the soli borings suggested that at least 1,200 cubic yards of vadose '. zone soil were impacted with gasoline range hydrocarbons, and to a much lesser extent, with diesel range petroleum hydrocarbons These data also demonstrated that the underlying groundwater was impacted and the gasoline ' plume within the groundwater appeared to trend off to the northeast in the assumed direction of groundwater flow ' 1.2 Scope of Work ' To further characterize the extent of hydrocarbon contamination from this fuel release, the following work was proposed, and then performed ' I A total of 6 shallow soil borings were drilled and converted groundwater monitoring wells One of these borings was drilled through the point of ' release, one was placed a short distance away in the presumed up-gradient position, and 4 others were placed at varying distances in the approximate down gradient direction The borings were logged by a registered geologist ' and soil samples were collected for geologic description and possible laboratory analysis (see boring logs in Appendix B) ' 2 One boring was drilled to a total depth of 90 feet and completed as a deep . groundwater monitoring well This well was intended to investigate the vertical distribution of hydrocarbons in the groundwater column The ' 2937 Veneman Ave ,#B240 Geo-Phase Environmental Inc Phone (209) 569-0293 Modesto, CA 95356 Fax (209) 569-0293 1