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CNN ', E' IT }� A S S O C I A T E S I N C level data were used to develop the groundwater elevation contour map (Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site generally flowed towards the south-southeast at an average hydraulic gradient calculated to be 0 001 ft/ft or approximately 6 8 ft/mile on June 11, 2002 A summary of groundwater monitoring data is presented in Table 1 ANALYTICAL RESULTS TPHg, TPHd, and BTEX were not detected In the samples collected from wells MW1, MW5, and MW6 Well MW2 was not sampled due to the presence of free product Wells MW3 and MW4 also did not have detectable concentrations of TPHg or BTEX, but did contain detectable amounts of TPHd at 67 and 120 parts per billion (ppb) respectively A summary of analytical results is presented in Table 2 Laboratory data sheets and chain-of-custody documentation are contained in Attachment 2 ADDITIONAL SITE ACTIVITIES On June 21, 2002 ATC personnel supervised the transport and disposal of approximately 85 gallons of monitoring well purge water A copy of the non-hazardous waste manifest is included in Attachment 1 CONCLUSIONS Concentrations from all wells remained generally consistent with the results from previous sampling events Wells MW1, MW5, and MW6 remained nondetect for sampled petroleum hydrocarbon constituents Free product was still present in well MW2, and wells MW3 and MW4 contained trace amounts of TPHd during this sampling event The direction and magnitude of groundwater flow is generally consistent with the previous sampling event, and groundwater elevations have decreased since April 2002 RECOMMENDATIONS Based on the results of the second quarter 2002 monitoring episode, we recommend the following • Conduct the third quarter 2002 groundwater monitoring and sampling of wells MW1 through MW6 and analyze samples for TPHg, TPHd, and BTEX W 1625001qua 1yl2gr-2002 doc 3