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. GROUNDWATER GRADIENT AND FLOW DIRECTION Figure 4 shows the groundwater elevation gradient and flow direction determined from depth to water measurements at the four on-site monitor wells on December 19, 2003 The groundwater elevation has decreased by an average of 0 99 feet since the previous quarterly monitoring round on August 7, 2003 The flow direction is to the northeast The overall gradient is 0 002 feet/linear foot RESULTS OF CERTIFIED ANALYSIS OF GROUNDWATER SAMPLES The results of the certified analyses of groundwater samples collected from the four monitor wells on December 19, 2003 are shown in Table 1 Copies of the laboratory reports are included as Appendix C of this report TPH-G concentrations in MW1-MW3 ranged from a maximum of 7800 ug/l at monitor well MW 1 to 1800 ug/l at monitor well MW2 Monitor well MW4, completed in a lower aquifer, showed a TPH-G concentration of 170 ug/1 Benzene concentrations in MW1-MW3 ranged from a maximum of 2700 ug/l at MW1 to 430 ug/1 at MW2 Monitor well MW4 showed a Benzene concentration of 0 61 ug/l MTBE concentrations in MW1-MW3 ranged from a maximum of 26 ug/1 at MW3 to 6 0 • ug/1 at MW2 MTBE was not detected above 0 5 ug/l in MW4 Figure 5 shows the distribution of TPH-G, BTEX, and MTBE in groundwater and the estimated lateral limits of the TPH-G in groundwater as determined from groundwater samples collected on December 12, 2001 The lateral limits of TPH-G in groundwater to the northeast are not yet determined, however, the preliminary results from Advanced Geo-Environmental, Inc CPT testing (December 2001) to the northeast suggest that the TPH-G in groundwater plume at the first groundwater depth of 25 feet bgs most likely extends beyond the property limits LIMITATIONS The discussion presented in this report is based on the following 1 The observations and data collected by field personnel 2 The results of laboratory analyses performed by a state certified analytical laboratory 3 Our understanding of the regulations of San Joaquin County and the State of California Changes in groundwater conditions can occur due to variations in rainfall, temperature, local and regional water use, and local construction practices In addition, variations in the soil and groundwater conditions could exist beyond the points explored in this investigation 3 Are Pumn 0%4 9-12 2001