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KEI-P89-1104 .QR7 July 19 , 1993 Page 2 checked for the presence of a sheen. No free product or sheen was noted in any of the wells during the semi-annual period. The monitoring data collected during this reporting period are summarized in Table 1 . Water samples were collected from all of the wells on June 21, 1993 . Prior to sampling, the wells were each purged of between 7 and 12 . 5 gallons of water by the use of a submersible pump. During purging operations, the field parameters pH, temperature, and electrical conductivity were recorded and are presented in Table 2 . Once the field parameters were observed to stabilize and a minimum of approximately four casing volumes had been removed from each well, water samples were then collected by the use of a clean Teflon bailer. The samples were decanted into clean VOA vials and/or one-liter amber bottles, as appropriate, which were then sealed with Teflon-lined screw caps and stored in a cooler, on ice, until delivery to a state-certified laboratory. HYDROLOGY The measured depth to ground water at the site on June 21, 1993 , ranged between 53 . 21 and 53 . 94 feet below grade. The water levels in all of the wells have shown net increases ranging from 2 . 88 to 2 . 93 feet since December 30 , 1992 . Based on the water level data gathered during the semi-annual period, the ground water flow direction was toward the east-northeast, as shown on the attached Potentiometric Surface Maps , Figures 1 and 2 . The flow direction has been predominantly to the east since October of 1990 . The average hydraulic gradient at the site on June 21, 1993 , was 0. 0015 . ANALYTICAL RESULTS The ground water samples were analyzed at Sequoia Analytical Laboratory and were accompanied by properly executed Chain of Custody documentation. The samples were analyzed for total petroleum hydrocarbons (TPH) as gasoline by EPA method 5030/modi- fied 8015, and benzene, toluene, ethylbenzene, and xylenes by EPA method 8020. In addition, the ground water sample collected from monitoring well MW1 was analyzed for TPH as diesel by EPA method 3510/modified 8015, and for EPA method 8010 and 8270 constituents. The concentrations of TPH as gasoline and benzene detected in the ground water samples collected on June 21, 1993 , are shown on the attached Figure 3 . The analytical results of all of the ground water samples collected from the monitoring wells to date are sum- marized in Tables 3 and 4 . Copies of the laboratory analytical results and the Chain of Custody documentation are attached to this report.