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Ti k levels required several hours after purging to 'near their initial levels. T. All soil and water samples were transported and submitted to the laboratory with appropriate chain-of-custody forms. Also submit- ted to the laboratory was one blind duplicate identified as fictitious MW4 to check analytical repeatability. 4 . 0 site Geology and Hydrogeology rbar.acte.rizat.:ion of the soil lithologies was based on cuttings �. rct urned by the augers and those brought to the surface by a hand,' auger. The lithology found was quite consistent across the site. Surface soils found 1-4 feet below ground surface are primarily clays with different admixtures of sand and silt. These sandy, 3,L. clays and clayey silts are unsaturated but generally ; slightly moist. soils below approximately 4 . 5 feet consist almost entirely of sandy clays (borehole BE contained silty clay) , and are generally moist. Saturated soils occur generally at 5-6 feet below qround surface. No sand or gravel lenses were observed at an;- depths and no perched water was observed at any sample locations. An examination of the water levels in the three monitoring wells at. this site for ;lune 1989 , indicates a localized groundwater gradient of 4. 0052 feet per foot toward the northeast (Figure 3) . This gradient direction agrees well with regional gradient information published by the San Joaquin County Flood Control and Water Conservation District (Unconfined and semi-confined water table elevations, spring 1989) , although the regional gradient is less steep (0 . 0022 feet per foot) . The steep local gradient may be a result of local topography and drainage conditions. It is not known whether or not the shallow groundwater beneath the site is part of the primary unconfined aquifer or if it is a shallow perched zone. Deeper borings at the site would be required to define the nature of the aquifer. The poor yield of the wells observed during the sampling program reflects low transmissivity which can be expected for soils containing extremely high amounts of clay as found on-site. This poor transmissivity suggests that movement of water both verti- cally and laterally is extremely slow. 5. 0 Analytical Results A total of 1S soil samples and 4 water samples were collected from the site. All samples collected at the site were submitted to the WESTON Analytics' Stockton, California laboratory. Portions of samples requiring carbamate analysis were subsequent- ly subcontracted to Appl , Inc. Laboratory in Fresno, California. Both laboratories are certified by the State of California for the analyses requested. - 5 -