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A sample of the purge water stored in the onsite polyethylene tank (coded "Tank 1") was
<br />collected for analysis of TPH-G and BTEX. Disposal of the accumulated purge and
<br />development water will be arranged through the Stockton City Municipal Utilities Environmental
<br />Control Department (MUECD) based on the analytical results
<br />2.2 Quarterly Monitoring Results
<br />A summary of the analytical results of the December 1992 groundwater monitoring event is
<br />displayed in Table 1 while the complete analytical reports are presented in Appendix B All
<br />samples are labeled to correspond to the well from which they were taken except for sample
<br />MW -15 which was a field decontamination procedure check sample and sample MW -22 which
<br />was a duplicate of primary sample MW -2 Both of the quality assurance samples were only
<br />analyzed for BTEX compounds
<br />TABLE 1
<br />December 1992 Analytical Results Summary
<br />Well
<br />TPH-G
<br />Benzene
<br />Toluene
<br />Ethylbenzene
<br />Xylene
<br />Total Lead
<br />Fecal Coliform
<br />(mglL)
<br />WIL)
<br />(fag/L)
<br />(.UglL)
<br />(µglL)
<br />(mglL)
<br />(MPN/100m1)
<br />MW -1
<br />ND,,5
<br />ND,,
<br />ND,,
<br />ND, U
<br />ND, o
<br />NA
<br />NA
<br />MW -2
<br />14
<br />1 440
<br />11
<br />ND,o
<br />14
<br />NA
<br />NA
<br />MW -3
<br />NDo05
<br />1 3
<br />ND, U
<br />ND, U
<br />ND,,
<br />NA
<br />NA
<br />MW -4
<br />ND,,
<br />ND, o
<br />ND, o
<br />ND, o
<br />ND,,
<br />NA
<br />NA
<br />MW -5
<br />ND,,
<br />3 0
<br />ND,,
<br />ND,,
<br />ND, 0
<br />NA
<br />NA
<br />MW -6
<br />NDo,5
<br />ND,,
<br />ND,,
<br />ND,,
<br />ND,,
<br />NA
<br />NA
<br />MW -15
<br />NA
<br />ND, o
<br />ND,,
<br />ND,,
<br />ND,,
<br />NA
<br />NA
<br />MW -22
<br />NA
<br />350
<br />12
<br />ND,o
<br />14
<br />NA
<br />NA
<br />Tank 1
<br />NDo w
<br />29
<br />ND, u
<br />ND,,,
<br />ND,,
<br />NA
<br />I NA
<br />ND = Non-detectable at the level of detection noted
<br />NA = Not analyzed
<br />To aid in the interpretation of trends over time, Table 2 presents a chronological record of
<br />groundwater monitoring results since the inception of the project
<br />As shown on Table 1, the only hydrocarbon compounds quantified during this quarter were
<br />benzene in MW -2 at 440 ug/L, in MW -3 at 1 3 1.g/L and in MW -5 at 3 0 µg/L, toluene in
<br />MW -2 at 11 µg/L, xylene in MW -2 at 14 µg/L, and TPH-G in MW -2 at 1 4 mg/L. For the
<br />decontamination check sample (MW -15), all BTEX compounds were non-detectable indicating
<br />that field procedures utilized were effective at eliminating potential cross contamination of the
<br />wells. For the field duplicate (MW -22) and the primary well sample (MW -2), similar
<br />concentrations were found in both samples except for benzene which was found at 350 µg/L in
<br />the duplicate versus 440 µg/L in the primary sample A review of internal lab procedures failed
<br />to find an error in calculations, therefore the duplicate analysis must be given equal weight in
<br />evaluating groundwater quality as the primary sample.
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<br />4 01 r2&93
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