ARCHIVED REPORTS XR0000084 - Laserfiche WebLink

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i As shown on Table 1, the only hydrocarbon compounds quantified during this quarter were benzene in MW-2 at 230 jcg/L and in MW-5 at 6 5 µglL and TPH-G in MW-3 at 0 62 mg/L ' For the decontamination check sample, all BTEX compounds were found as non-detectable indicating that field procedures utilized were effective at eliminating potential cross contamina- tion of the wells For the field duplicate, similar concentrations were found in both samples ' except for benzene which was found at 420 µglL in the duplicate versus 230 µg/L in the primary sample A review of internal lab procedures failed to find an error in calculations, therefore the duplicate analysis must be given equal weight in evaluating groundwater quality as the primary ' sample As shown on Table 2, groundwater quality trends at the site indicate that the only compound ' currently found in significant concentration in groundwater at the site is benzene However, the compound was found only in wells MW-2 and the newly installed MW-5 at the southeast corner of the site The chart also shows that lead a _pears to have been detected in the groundwater for ' the first time This is unlikely and the re orted-soncentrations are likely due to variability of thea ual-lead concentration near the detection limit of the analytical instrumentation n any case, the concentrations are not sufficient to be viewed as an environmental problem associated ' with the site In regard to fecal coliform, no detectable concentrations were found in any of the monitor wells ' During the monitor well sampling, the depth to groundwater was measured in all wells and the data converted to Mean Sea Level (MSL) elevations for the purpose of plotting groundwater gradient and direction at the site Figure 3 presents a graphical interpretation of the data which shows the groundwater direction is generally east at the north end of the site and varying toward the southeast beneath the southern portion of the site While this information appears to be ' different than the flow direction reported in previous quarters (northeast), the difference is likely due only to the effect of more information available from over a wider area than previously available due to the installation of the three new monitor wells Therefore, it is unlikely there ' has been any significant shift in the flow direction during this quarter 3.0 REMEDIAL INVESTIGATION STATUS This section presents information related to activities completed (investigatory or remedial) at the site during the time period July 1992 through October 1992 A revision of the previously ' developed remedial plan is also presented which is based on recently developed site data 3.1 Third Quarter 1992 Activities ' As discussed in the introduction to this report, the remedial plan previously developed for the site included expansion of the original groundwater monitor well field of three wells, removal ' of remaining underground piping and installation of a soil vapor extraction (SVE) system to treat the stockpiled soils onsite as well as any remaining in-place soils in the tank excavation area Work related to this plan commenced in early September as discussed below 1 � MC\RPTs1AREG3QT1t WP 6 W13/92 ' I