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' 3-2 encountered in other areas of the site, except for Boring MW-4 winch contained approxi- mately two feet of loose gravel from a former railroad spur that has been removed I In areas where fill is not present, a dark brown silt was encountered from the ground surface �r to 2 ft-bgs The silt was generally dry and contained organic material Underlying the fill and/or silt units and typically to the bottom of the borings (16 to 18 ft-bgs), a dark brown to brown silty clay was encountered In the vicinity of the former UFT, the silty clay was believed to be stamed by gasoline constituents and appeared gray to greenish-gray in color, and often had a petroleum odor associated with the staining Gener- ally, the silty clay unit contained trace amounts of fine sand at depths of 12 to 18 ft-bgs The moisture content generally increased with depth and the silty clay unit often became saturated near the bottom of the borings at depths from 12 to 16 feet 312 Hydmgeology The site is located in the Central Valley portion of California The unconsolidated sediments comprising the aquifer system include gravel, sand, silt, and clay and are of both marine and non-marine origin Ground water occurs under both confined and water table conditions Ground water at the site was typically encountered at a depth of 12 to 14 ft-bgs and in some instances static water levels were recorded at higher elevations in the completed monitoring wells, suggesting locally confined or semi-confined conditions A potentnometrnc surface map was prepared based on water levels obtained on August 26, 1994 (Table 4) The poten- tiometric surface, depicted in Figure 4, shows shallow ground water generally flowing to the north-northwest with a hydraulic gradient of approximately 0 004 foot per foot (ft/ft) There is an indication that the two supply wells may be affecting the shallow water-bearing zone (Figure 4) The ground water flow direction appears to change to a more northwesterly direction in the vicinity of the supply wells (Figure 4) Remcor has not been able to obtain detailed information concerning, construction (total depth, screened interval, cased inter- val[s]), lnthologic boring logs, water levels, or pumping rates of these two supply wells, this 29025 ' "REALISTIC SOLUTIONS FOR HAZARDOUS WASTE PROBLEMS"