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0 <br />The unsaturated zone beneath the landfill is approximately 250 feet <br />thick. A minor perched zone of ground water was encountered within <br />silty interbeds of the Corcoran Clay to a depth of 20 feet in Boring <br />MW -1. However, no ground water was encountered in exploratory borings <br />drilled by J.H. Kleinfelder and Associates through the Corcoran Clay. <br />The areal extent of a perched zone within the Corcoran Clay is likely <br />to be restricted to the northern portion of the landfill site, since <br />it appears that this is the only area where the Corcoran Clay is <br />present in the subsurface. <br />Ground water of a deeper regional aquifer occurs at a depth of approx- <br />imately 250 feet in Well MW -1 at the site. The general ground -water <br />flow direction in this deeper aquifer is presumed to be from the <br />mountains southwest of the site towards the San Joaquin Valley to the <br />northeast. <br />Ground water in the vicinity of the landfill recharges water -bearing <br />zones in the San Joaquin Valley. To the east of the landfill within <br />the San Joaquin Valley, the Corcoran Clay Member forms a confining <br />zone separating an upper water -bearing zone from a lower, confined <br />water -bearing zone. <br />The ground -water monitoring well at the site (Well MW -1; see Figure 2) <br />was sampled in October 1987. This well is believed to be downgradient <br />of the landfill. The ground water was analyzed for volatile, semi - <br />volatile, and nonvolatile organic compounds, pesticides, phenols, <br />metals, and other general water -quality parameters. Results of the <br />testing indicate little or no impact from the landfill on water <br />quality (EMCON Associates, 1988). No hazardous constituents were <br />detected in the ground water. Concentrations of inorganic and general <br />water -quality parameters were within ranges expected for ground water <br />in this setting. <br />7 <br />