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. +Y'..Wb6s.r'xuaiYa.J.:._✓....uYuAaN'iu.a(uu.ata'.n, v.'s ".v cs..'.'.�.n.�..:w._ i Project No. 8753009Q-AN02 f Woodward-Clyde Consultants i i was shaken and sniffed for odors immediately after removing the lid; and the presence of a product film or sheen on the water surface was noted, if present (Table C-1, Appendix C). PRELIMINARY EVALUATION OF HYDROGEOLOGIC SETTING Site Hydrology Based on groundwater elevation measurements obtained on January 28, 1987 and February 12, 1987, two potentiometric contour maps were constructed for the tank terminal area (Figures 3 and 4). The water table elevations are not absolute; they are reported only with respect to the piezometer elevation survey reference (ARCO telephone vault; unknown elevation). The flow direction on both dates appears generally to be from the north- west to the southeast. The deep water channel and San Joaquin River are located north and west respectively, of the tank terminal area. In both cases, a groundwater mound is shown in the vicinity of piezometers PH and P12. The location of the mound coincides with the location of an unlined pond immediately west of P11 and P12. Radial flow extending from the mound may result in local shifts in the flow direction. i I Due to the lack of water elevation measurements in the tank terminal interior, groundwater movement in the central area of the site is not well defined. The northern area of the site generally shows flow crossing the site from west to east (towards the cogeneration facility). The southern I area of the site is affected by the groundwater mound and flow is predomi- nantly to the south (towards the Learner Lease property). Site Stratigraphy A review of site stratigraphy based on the geotechnical boring logs provided by Time Oil Company and ST Services indicates the area is underlain by alternating fine and coarser-grained strata (see Appendix R). The alternating layers of fine-grained (clay) and coarser-grained (stiff -7-