ARCHIVED REPORTS XR0005781 - Laserfiche WebLink

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MW-4 revealed detectable amounts of BTEX, the first time this well has shown any contamination. However, due to bailer blank "hits" , the results cannot be relied on as representative Mw-5 also recorded a minor amount of contamination, (benzene, ) for the first time since sampling began Again, bailer blank contamination most likely skewed the results CONCLUSIONS Based upon an analysis of all data collected to date, the following conclusions can be made 1 The horizontal & vertical limits of the soil & groundwater plume have been defined in all directions We do not believe that the ethylbenzene, xylene, & TPHg which were detected in SP-3 are from another source, since none has been identified That anomaly may be the result of changes in lithology, or manmade conduits, (sewer & water lines, etc ) 2 The hydraulic gradient has been primarily to the north, which agrees well with regional data The depth to groundwater has varied an average of 3 69 ' (highest to lowest, ) or a change of about 18$ 3 There does not appear to be a valid correlation between levels of contamination, fluctuations of water table depth, or groundwater gradient 4 Based upon maps drawn on concentration levels, (PLATES II-VI, ) the soil & groundwater plumes have not migrated far from the original source, (the UST' s ) 5 Because the limits of soil & groundwater contamination have been defined in all directions, further investigative work does / not appear warranted RECOMMENDATIONS 1 Perform one more quarterly sampling of the 5 wells to confirm whether or not the contaminated bailer blanks affected the results obtained from the December sampling event If MW-4 & MW-5 are below detection levels, they should be dropped from the quarterly sampling 2 Solicit bids from qualified environmental firms for proposals to design, install, & operate a soil/water remediation system 7