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1.0 Site Location and Description The JC Trucking property is located in the southern section of the city of Stockton, San Joaquin County, California, between Jackson Street on the north, Clay Street on the south, and South Aurora Street on the east (Figure 1). Private residences border the property on its west side, and primarily commercial enterprises line South'Aurora Street to the east. The property presently consists of an unpaved rectangular lot with a 50 by 30 foot concrete slab at its northeast corner, the site of the former office building, and a four foot high 100 by 40 foot foundation for the former loading dock situated along the center of the east side of the property. The site was formerly a truck terminal and was closed in February 1991, after a fire. Two 3000 gallon underground gasoline storage tanks were located in the northwest corner and two 3000 gallon underground diesel storage tanks were� located in northeastern corner of the site. The two former tank location sites are indicated by depressions in the ground surface. Figure 2 shows the site layout and the location of the tank excavations. 2.0 Cross Sections ` Two cross sections, intersecting at monitor well MW-7A (figure 2), are provided to show subsurface lithology. Lithology from ten of the twelve monitor wells are represented in the cross sections. Monitor wells MW-1 and MW-3 are outside"of the contaminant plume and are not depicted in the cross sections. The lithology from wells MW-2 and MW-8 were composited-;to show the total stratigraphy. MW-2 provided the lithology for the upper structures, from the surface to approximately 45 I!, feet below the ground surface (bgs), and MW-8 the deeper lithology, 45 feet bgs to total depth. Similarly, lithology from wells MW-10 and MW-11 were composited. Cross section A-A' and cross section B-B', along with graphic contaminant distributions for sections A-A' and B-B' are included as figures 3 through 6. The lithology shown on the cross sections were taken from the data depicted on the boring logs submitted with the various well installation and site assessment reports that have been previously prepared from this site. The original field"notes may not be any longer E available. However, the boring logs are designed to accurately reflect the lithology as interpreted by the on-site field geologist at the time of drilling and sampling. 4 3.0 Mass Balance of Petroleum Hydrocarbon Quantities The mass balance quantities reflect approximate location and time-dependent contaminant quantities. They are best used empirically to make general assessments regarding contaminant diffusion and degradation, and should not be construed as defining actual mass quantities. These calculations were done in j very general terms and were based on limited data. Mass balance values currently generated for this workplan are not as relevant as future values will be after the remediation process has finished and the site JJW GEOSCIENCES Inc.