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RESULTS OF CERTIFIED ANALYSIS OF GROUNDWATER SAMPLES <br /> The results of the certified analyses of groundwater samples collected from the three <br /> monitor wells on May 12, 1999 are shown in Table 1 Copies of the laboratory reports <br /> are included as Appendix D of this report <br /> TPH-G concentrations ranged from a maximum of 13000 ug/I at monitor well MW1 to <br /> 3900 ug/l at monitor well MW2 <br /> Benzene concentrations ranged from a maximum of 3700 ug/l at MW 1 to 740 ug/1 at <br /> MW2 <br /> MTBE concentrations ranged from a maximum of 110 ug/l at MW 1 to 6 ug/1 in MW3 <br /> Figure 5 shows the distribution of TPH-G, BTEX, and MTBE in groundwater and the <br /> estimated lateral limits of the TPH-G in groundwater as determined from groundwater <br /> samples collected on May 12, 1999 The increase in overall groundwater elevation has <br /> been accompanied by an increase in concentrations of TPH-G and BTEX at all three <br /> monitor wells <br /> RECOMMENDATIONS <br /> 1) Continue quarterly groundwater monitoring <br /> 2) Construct a workplan to further assess the lateral and vertical extent of soil and <br /> groundwater contamination originating from the former UST at the site The assessment <br /> should address the potential impact on soil and groundwater from possible releases <br /> during periods of reduced groundwater elevation WEGE has determined that the top of <br /> groundwater in site vicinity receded to its lowest recorded elevation (since 1965) in <br /> October 1977 of 60-65 feet below mean sea level (72-77 feet bgs) <br /> LIMITATIONS <br /> The discussion presented in this report is based on the following <br /> 1 The observations and data collected by field personnel <br /> 2 The results of laboratory analyses performed by a state certified analytical laboratory <br /> 3 Our understanding of the regulations of San Joaquin County and the State of <br /> California <br /> Changes in groundwater conditions can occur due to variations in rainfall, temperature, <br /> local and regional water use, and local construction practices In addition, variations in <br /> the soil and groundwater conditions could exist beyond the points explored in this <br /> 101 investigation <br /> 3 Are Pump QM 4-6 1999 <br />