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<br /> placed to the west of the former tank bed, could only be advanced to a depth of 78 feet bgs due to
<br /> difficult drilling conditions Well details are contained in Appendix C of SECOR's report
<br /> Because the extent of shallow sod contamination was defined during earlier investigative activities, sod
<br /> samples were collected only from depths of 25 feet and greater Based on field instrumentation
<br /> readings, four to five soil samples from each drilling location were submitted to a laboratory and
<br /> analyzed for total petroleum hydrocarbons as gasoline (TPH) and also for benzene, toluene,
<br /> ethylbenzene, and xylenes (BTEX) Gasoline was found in the samples collected from MW-1 at 35 feet
<br /> (3 4 ppm), 45 feet (680 ppm), 83 feet (3 2 ppm), and 100 feet (1 6 ppm), varying concentrations of BTEX
<br /> were also found in these samples Trace concentrations of benzene, ethylbenzene, and xylenes (none
<br /> exceeding 0 01 ppm) were also found in the samples collected from MW-2 at 45 feet, 55 feet, and 60
<br /> feet, and in the sample collected from MW-5 at 71 feet Hydrocarbons were not identified in any of the
<br /> remaining samples Table 1 in SECOR's report summarizes analytical results and Appendix A contains
<br /> laboratory reports
<br /> On January 19, 1995, the groundwater monitoring wells were purged and sampled Prior to purging,
<br /> measurements were collected from each well to evaluate groundwater elevation, flow direction, and
<br /> gradient During field activities, groundwater with a southeasterly flow and a hydraulic gradient of 0 13
<br /> ft/ft was encountered at 75 96 feet bgs to 86 80 feet bgs
<br /> Hydrocarbons were found in groundwater samples collected from each of the monitoring wells The
<br /> sample collected from MW-1 contained 5,200 ppb TPH, 200 ppb benzene, 1,100 ppb toluene, 160 ppb
<br /> ethylbenzene, and 620 ppb xylenes The sample collected from MW-2 was found to contain 460 ppb
<br /> TPH, 30 ppb benzene, 48 ppb toluene, 5 ppb ethylbenzene, and 30 ppb xylenes Analysis of the sample
<br /> collected from MW-3 indicated 430 ppb TPH, 18 ppb benzene, 48 ppb toluene, 13 ppb ethylbenzene,
<br /> and 70 ppb xylenes Analyses identified 100 ppb TPH, 2 3 ppb benzene, and 0 6 ppb xylenes in the
<br /> . sample collected form MW-4 Table 3 in SECOR's report summarizes analytical results and Appendix A
<br /> contains laboratory reports
<br /> Conclusions
<br /> At this time, it appears as though there may be two areas of soil contamination at the subject site one
<br /> shallow and one deep It appears that the extent of shallow soil contamination has been defined and
<br /> does not appear to extend much beyond the limits of the former tank bed The vertical migration of
<br /> shallow sod contamination may be limited by the lens of clayey silt existing at 30 to 35 feet bgs Deeper
<br /> contamination (beginning at approximately 40 feet to 45 feet bgs) appears to be present at highest
<br /> concentration to the northeast of the former tank bed The extent of deeper soil contamination Is fairly
<br /> well defined to the northeast, southeast, and west by the samples collected during the additional site
<br /> investigation, however, it may need to be further investigated to the north and south Time's records do
<br /> not indicate any potential sources for the deep sod contamination noted in the vicinity of MW-1 Since
<br /> this deeper contamination is some distance from the former tank bed, we believe that it may be due to
<br /> an offsite hydrocarbon source
<br /> The extent of groundwater contamination has not been defined in any direction and appears to extend
<br /> offsite to the north, south, and east The elevated concentrations of hydrocarbons in MW-1 and MW-2
<br /> (both sidegradient of the former tanks), suggest that an offsite source of hydrocarbons may be impacting
<br /> the subject site
<br /> Time has reviewed several reports concerning the Beacon Station located immediately to the north of
<br /> the subject site It is Time's understanding that a "dry well"
<br /> was once present on the southeast comer of
<br /> the Beacon Station property This dry well, located immediately upgradient of MW-1 and MW-2, could
<br /> be a potential source of contamination to deeper soils Investigation performed near a second dry well,
<br /> located on the southwest portion of the Beacon property, revealed significant groundwater contamination
<br /> which has not yet been defined in the downgradient direction
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