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KEI-P89-1104 .QR5 July 24, 1992 Page 2 HYDROLOGY The measured depth to ground water at the site on June 22 , 1992 , ranged between 56. 63 and 57 . 43 feet below grade. The water levels in all of the wells have shown a net decrease ranging from 1. 18 to 1. 24 feet since December 30, 1991. Based on the water level data gathered on June 22 , 1992 , the ground water flow direction appeared to be to the east-southeast, as shown on the attached Figure 1. The flow direction reported on this date is relatively unchanged from the flow direction reported in the previous quarters. The average hydraulic gradient across the site on June 22 , 1992 ranged between 0. 001 and 0. 0007 . 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, xylenes, and ethylbenzene (BTX&E) 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 constituents. The ground water sample analytical results are summarized in Tables 2 and 3 . Copies of the laboratory analytical results and Chain of Custody documentation are attached to this report. DISCUSSION AND RECOMMENDATIONS Based on the analytical results for the ground water samples collected and evaluated to date, and no evidence of free product or sheen in any of the wells, KEI recommends the continuation of the current quarterly monitoring and semi-annual sampling program of the existing wells, per KEI ' s proposal (KEI-P89-1104 .P5) dated December 10, 1990, and as modified in KEI ' s quarterly report (KEI- P89-1104 .QR4) dated February 3 , 1992 . The analytical results for the ground water sample collected from well MW1 during the most recent sampling event indicated a concentration of 180 parts per billion (ppb) of high boiling point (HPB) hydrocarbons. However, as shown on the attached laboratory analysis sheet, the analytical laboratory noted that the sample "does not appear to contain diesel. HBP is due to several unidentified, non-fuel peaks. " During the next sampling event, if the ground water sample from MWl indicates a detectable concentra- tion of HPB hydrocarbons, KEI recommends that the sample also be analyzed by EPA method 8270 in order to determine the unidentified 40 peaks.