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KEI-P91-0202 .QR4 April 13 , 1993 Page 3 method 8020. In addition, the ground water samples collected from monitoring wells MW1, MW7 , MW8, and MW9 were analyzed for fecal coliform by the membrane filter method. The ground water sample analytical results are summarized in Table 3 . The concentrations of TPH as gasoline and benzene detected in the ground water samples collected this semi-annual period are shown on the attached Figure 5 . Copies of the laboratory analyti- cal results and the 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 ground water monitoring and sampling program. The wells are currently monitored quarterly and sampled semi-annually. The results of the monitoring and sampling program will be documented and evaluated after each monitoring and sampling event, and . recommendations for altering or terminating the program will be made as warranted. In January of 1993 , KEI conducted a survey of water wells located within a 1/2 mile radius of the subject site in order to identify the location of potential ground water contaminant receptor areas. The survey indicated the existence of five domestic wells and three sites with monitoring wells. The well locations were determined by a review of the California Department of Water Resources (CDWR) records. The water wells identified in the study area, along with well information, survey numbers, owners, and locations, are listed in Table 4 . The approximate locations of the water wells are shown on the attached Figure 6 . Domestic wells are located at sites #1, #4 , #5, #6, and #7 , and monitoring wells are located at sites #2 , #3 , and #8 . Based on a consistent southern gradient at the subject Unocal site, sites #6 and #7 are located downgradient of Unocal. Sites #1, #3 , #4 , and #5 are located either upgradient or cross-gradient of the subject Unocal site. The two downgradient sites (#6 and #7) are located approximately 1, 500 feet and 2 , 000 feet from the Unocal site, respectively. It is important to note that ground water samples collected from the most downgradient well (MW8) at the Unocal site have consistently indicated non-detectable concentrations of TPH as gasoline and BTX&E since the inception of sampling on January 3 , . 1992 (over one hydrologic cycle) . Based on the consistent southerly ground water flow direction, the distance to the nearest potential receptor wells, and the consistent non-detectable