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Martin Thorpe " v 16 October 1987 10 waissassocinrFs was detected at 5.4 ppb in MW-1. Soluble lead concentrations ranged from # below detection in MW-2 to 3 ppb in MW-1. One ppb lead was detected in MW-3. GC/FID analysis of the development water composite sample collected by WA was below the detection limits of 1 ppm for TFHC and .05 ppm for BTX. Based on these results Fran Forkas of the LDPW authorized discharge of the development water to the ground surface. Prior to the 8 September sampling, B&C discharged the drummed WA development water. They then directed their sampling purge water to the emptied drums. At the conclusion of their sampling, they collected samples from the drums which were composited at B&C and analyzed by EPA Method 602 for BTX. GC/PID analysis of the B&C purge water indicated 1,200 ppb benzene, 150 ppb ethylbenzene, 160 ppb toluene and 1,600 total xylene isomers. This water will be disposed of appropriately. Analytic results for water samples are presented in laboratory report forms are included in Attachment g Table 2 and copies of GROUND WATER GRADIENT Top-of-casing (TOC) elevations were surveyed on 1.1 August 1987. The datum elevation for the survey was USGS benchmark #191, located at the southeast corner of the intersection of Lodi Avenue and Stockton Street. TOC elevations and water level data are presented in Table 3. Two water table elevation maps were prepared for this investigation. Figure 3 shows water level data collected on 25 August and Figure 4 shows data collected on 11 September 1987. Both figures indicate a north to northeastward ground water flow, although Figure 3 indicates a more pronounced eastward component. The gradients shown in Figures 3 and 4 are opposite to the southwestward direction of ground water flow suggested by local topography Iand the regional hydraulic gradient.