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**p SITE TOPOGRAPHY/GEOLOGY The site is situated at approximately 100 ft above sea level on land which slopes gently to the west towards the San Joaquin River. The river lies approximately one and a half miles away and drains northwest- ward towards the central axis of the San Joaquin valley. The geology of the area is predominantly alluvial in nature and consists of gravels, sands, silts, and clays. The alluvium has been derived from the western slope of the Sierra Nevada and consequently dips gently to the west. This unit constitutes the water bearing zone under consideration and is considered to be unconfined although small pockets of confined hy- draulic conditions have been noted in reports pertaining to the Stockton area. Depth to groundwater is approximately 20 feet and as a result of the surface topography and proximity/drainage pattern of the nearby river, it is estimated that the subsurface flow trends to the west. SITE INVESTIGATIVE PLAN Soil Contamination Delineation The investigation of contamination at the site will be carried out in two phases. The initial phase will consist of the delineation of con- amination in the soil. This task will be performed by coring down at 5 foot intervals at specified locations (see Figure 2) and obtaining samples from the lower 18 inches of the interval with a California split spoon sampler. The sampler will be equipped with a brass sleeve and decontaminated by the following procedure prior to its re-use: * Wash with nonphosphate detergent * Rinse with tap water * Rinse at least once with deionized organic-free tap water Samples will be collected until groundwater is encountered and the auger flights used to core into the substrata will be steam cleaned prior to their re-use at another location. The soil samples will be analyzed for the following constituents: 1) Benzene 2) Toluene 3) Xylene 4) Ethyl benzene (Above sampled by EPA method 8020) 5) Diesel 6) Motor Oil The soil samples will be stored on ice until their delivery to a California certified laboratory. The soil sampling locations are situated so that contours of the. con- centrations of the analyzed constituents can be drawn and a good es-