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• Page 2 <br /> GEOLOGICAL AND HYDROGEOLOGICAL OVERVIEW <br /> According to information contained within the September, <br /> 1991 WaterWork assessment , the Reeve's site is located on <br /> level terrain underlain by flood plain deposits of <br /> Pleistocene and Holocene age that are composed of sediments <br /> similar to , and probably conformable on, underlying <br /> deposits of alluvium and Tulare formation. The flood plain <br /> deposits are light to dark-brown and grey clay, silty sand, <br /> and organic materials with locally high concentrations of <br /> salt and alkali . Stream channel deposits of sand and <br /> gravel are also included . <br /> Groundwater within the shallow water bearing zone occurs <br /> less than ten feet below grade at the site as well as over <br /> most of the Tracy area. General groundwater gradient is to <br /> the north. The flood plain deposits of the shallow water <br /> bearing zone have well developed soil profiles and, <br /> consequently, exhibit poor permeability The base of the <br /> shallow zone is poorly defined and probably is from five to <br /> twenty feet below ground surface. <br /> FURTHER DEFINITION OF THE CONTAMINANT PLUME <br /> Placement and Sampling of Additional Exploratory Soil <br /> Borings Along Grant Line Road <br /> On March 17 , 1994, Del Tech Geotechnical Support Services <br /> of Oakdale advanced four ( 4) soil borings (designated EP-1 , <br /> EP-2 , EP-3 , and EP-4) along the portion of the south <br /> sidewalk of Grant Line Road adjacent to the subject site. <br /> Each boring was advanced with a hand auger. Discrete soil <br /> samples and a grab water sample were acquired from each <br /> borehole . Each soil sample was collected within a 1 . 9 inch <br /> diameter by 4.0 inch long clean brass sleeve fitted within <br /> a drive sampler lowered into the borehole to a point <br /> accessed by the hand auger. Upon being retrieved, the <br /> drive sampler was opened and the brass sleeve removed. The <br /> ends of each sleeve were then covered with teflon sheeting/ <br /> aluminum foil , fitted with plastic caps, and sealed with <br /> duct tape. Each tube was then marked and placed in an <br /> iced, insulated container for transportation to Priority <br /> Environmental Labs of Milpitas, a California-state <br /> certified hazardous waste analytical laboratory, under <br /> chain of custody. Subsequent analyses were performed for <br /> Total Petroleum Hydrocarbons as Diesel (TPH-D) , Total <br /> Petroleum Hydrocarbons as Gasoline (TPH-G) , benzene, <br /> toluene, ethylbenzene, and total xylenes (BTEX) using EPA <br /> �� Methods 3550/8015 and 5030/8015-8020 , respectively. <br />