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a <br />A S S O C I A T E S I N C <br />• GROUNDWATER FLOW DIRECTION <br />Water level measurements were collected from wells MW1 through MW5 on June 13, 2000 <br />Water levels ranged from 19 51 to 20 36 feet below the tops of the well casing elevations, <br />representing an average increase in the water table elevation of approximately 0 46 feet since <br />March 2000 The water level data were used to develop the groundwater elevation contour map <br />(Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost <br />aquifer beneath the site flowed towards the southwest The average hydraulic gradient on June <br />13, 2000 was calculated to be 0 0009 ft/ft or approximately 5 ft/mile A summary of <br />groundwater monitoring data is presented in Table 1 <br />ANALYTICAL RESULTS <br />The groundwater sample collected from well MW2 contained detectable concentrations of TPHg, <br />TPHd, toluene, ethylbenzene, and xylenes The TPHg concentration was 2,700 parts per billion <br />(ppb), the TPHd concentration was 320 ppb, and toluene, ethylbenzene, and xylenes <br />concentrations ranged from 0 8 to 380 ppb <br />The groundwater samples collected from well MW4 contained TPHd at concentrations of 63 <br />ppb The groundwater samples from well MW4 did not contain detectable concentrations of <br />TPHg or BTEX The groundwater samples from wells MW 1, MW3, and MW5 did not contain <br />detectable concentrations of TPHg, TPHd, or BTEX Analytical results of groundwater samples <br />are summarized in Table 2 and laboratory data sheets are contained in Attachment 2 <br />CONCLUSIONS <br />Concentrations from wells MW1 through MW5 generally decreased or remained the same since <br />the previous sampling event The direction of groundwater flow is consistent with the previous <br />event Groundwater elevations have increased since March 2000 <br />RECOMMENDATIONS <br />Based on the results of the second quarter 2000 monitoring episode, we recommend the <br />following <br />• Perform third quarter 2000 monitoring event and analyze samples from the monitoring wells <br />for TPHg, TPHd, and BTEX <br />• Once two additional quarters of monitoring indicate the petroleum hydrocarbon plume is <br />stable, ATC will recommend site closure <br />0 <br />w \130991quart1yl2gr-2000 doc 3 <br />