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KEI-P88-1013 .QR2 December 10 , 1992 Page 2 Water samples were collected from the existing wells (except MW6) on September 30, 1992 . Prior to sampling, the wells were each purged of between 5 and 8 gallons of water by the use of a surface PUMP. The samples were collected by the use of a clean Teflon bailer. The samples were decanted into clean VOA vials that 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 the site on September 30, 1992 , ranged between 61. 75 and 62 . 76 feet below grade. The water levels in all of the wells have shown net decreases ranging from 0. 6 to 0 . 9 feet since June 3 , 1992 . Based on the water level data gathered on September 30, 1992 , the ground water flow direction appeared to be to the south, as shown on the attached Potentiomet- ric Surface Map, Figure 1. The average hydraulic gradient across the site was approximately 0. 01 on September 30 , 1992 . 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 , benzene, toluene, xylenes, and ethylbenzene (BTX&E) by EPA method 8020, and for EPA method 8010 constituents . The ground water sample analytical results are summarized in Table 2 . The concentrations of TPH as gasoline and benzene detected in the ground water samples collected this quarter are shown on the attached Figure 2 . Copies of the laboratory analytical results and Chain of Custody documentati-on 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 ground water monitoring and sampling program, per KEI ' s proposal (KEI-P88-1013 . P2) dated August 23 , 1991 , and as modified in KEI ' s report (KEI-P88-1013 .R2) dated July 15, 1992 . In order to comply with a request from the San Joaquin County ublic Health Services (SJCPHS) Department, KEI recommends the _ 1--pinsta.1l.ation of an additional monitoring well as a replacement for former well MW9 . This well , identified as 14 , is shown on the attached Figure 3 . In addition, in order to comply with a request