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I, <br /> . A S S O C I A T E S I N C <br /> ANALYTICAL RESULTS <br /> TPHg and BTEX were detected above laboratory method detection limits in the samples <br /> collected from wells MWl, MW3, MW5, MW6, and MW7 The samples collected from wells <br /> MW2, MW4, and CW contained no detectable concentrations of petroleum hydrocarbons <br /> Groundwater samples from wells MWi, MW3, and MW7 continue to contain elevated <br /> concentrations of TPHg and BTEX A summary of analytical results is presented in Table 1 <br /> Laboratory data sheets and chain-of-custody documentation are contained in Attachment 2 <br /> GROUNDWATER FLOW DIRECTION <br /> Water level measurements were collected from wells MW1 through MW7, and CW on <br /> December 21, 1999 Water levels ranged from 22 10 to 24 82 feet below the tops of the well <br /> casing elevations, representing an average decrease in the water table elevation of approximately <br /> 0 63 feet since October 1999 The water level data were used to develop the groundwater <br /> elevation contour map (Figure 3) Assuming that horizontal isotropic conditions prevail, <br /> groundwater in the uppermost aquifer beneath the site flowed towards the northeast The average <br /> hydraulic gradient on December 21, 1999 was calculated to be 0 004 ft/ft or approximately 21 <br /> ft/mile There appears to be a mounding effect in the vicinity of wells MW 1 and MW3 that has <br /> • not appeared during previous groundwater monitoring events A summary of groundwater <br /> monitoring data is presented in Table 1 <br /> CONCLUSIONS <br /> Concentrations from wells MW1 through MW7 and CW remain consistent with the results from <br /> previous sampling events It appears as though there are petroleum hydrocarbons remaining in <br /> the soil The direction of groundwater flow and the magnitude of hydraulic gradient are <br /> generally consistent with the previous event Groundwater elevations have decreased since <br /> December 1999 <br /> RECOMMENDATIONS <br /> Based on the results of the Fourth quarter 1999 monitoring episode, we recommend the <br /> following <br /> o Conduct the First Quarter 2000 groundwater monitoring and sampling wells MW 1 <br /> through MW7 and CW and analyze samples for TPHg and BTEX by EPA Method 8020 <br /> • <br /> w 1625961quartlyl4gr-1999 doe 3 <br />