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and a groundwater sample was collected using the 'A-inch diameter Teflon tubing as described previously. ' The thud boring (83-1) was drilled to a depth of 41 feet bgs and was located along the eastern edge of the former UST excavation (Figure 3). Soil samples were prepared for laboratory ' submittal as in the first two borings Moderate product odor was detected in the core sample at 10.5 feet bgs and very strong product odor was detected in the core sample collected from 20 to 22 feet bgs. As in the first two borings, product odor and PID readings during ' headspace screening of soil samples diminished substantially below this depth. Standing water was not present in the boring after collection of core samples at 11 or 17 feet bgs The ' Screen-Point Sampler was used to attempt a depth-discrete sample from lb to 20 feet bgs, but no groundwater entered the screen. Water was observed to be flowing into the boring after collection of the core sample from 20 to 22 feet bgs, and a groundwater sample was collected ' at this depth using the slotted-screen method described above. This sample was collected within the interval of strongest soil discoloration and product odor, and very strong petroleum odors were detected within the water sample Following completion of soil sampling in boring ' B3-1, the three borings were grouted to the surface with neat cement per PHS/EHD guidelines ' Soil and groundwater samples were placed in an ice-cooled chest and submitted under chain-of- custody procedures to BSK Analytical Laboratories (BSK), a California DHS-certified laboratory for PHC analyses Samples were analyzed for BTEX, TPHg, and MTBE using EPA Methods 801518020. Since both former tanks at Site 3 contained unleaded gasoline, Carol Oz of PHS/EHD provided verbal authorization on August 7 that analysis for total lead would not be required for samples collected at Site 3 1 ' 4.0 INVESTIGATION FINDINGS Findings of the investigation, including geologic and hydrologic characteristics, and analytical ' results of the soil and groundwater samples, are discussed in the following sections ' 4.1 GEOLOGIC AND HYDROLOGIC CHARACTERISTICS ' The site is located on the delta of the San Joaquin River, approximately 2 miles east of the confluence of the San Joaquin and Calaveras Rivers. The subsurface geology consists of a thick sequence of alluvial deposits of late Tertiary to Holocene Age, overlying sedimentary ' rocks of Cretaceous to Tertiary age, which in turn overlie crystalline basement rocks (Bartow and Nilsen, 1990). Data from nearby studies within the Port area indicate a soil profile to a ' 7 98117UNVRFTS% iUffM RPP BOYARAN & ROSS, INC Environmental Scientists & Engineers