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July 30, 1998
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<br /> presented in Table 1 A TPH-gBenzene/TPH-d concentration map for second quarter 1998,
<br /> is shown as Figure 2
<br /> DISSOLVED-PHASE HYDROCARBONS
<br /> 1 ,
<br /> Gasoline Hydrocarbons (TPH-g):
<br /> TPH-g in groundwater samples was measured using EPA Method 8020 TPH-g was reported
<br /> in 7 of the 26 wells sampled (MW-1, 2, 3, 5, 8, 15, and 16) Detected TPH-g concentrations
<br /> ranged from 146 parts per billion (ppb) in MW-8 to 11,300 ppb in well MW-3 Well MW-5
<br /> shows a significant increase of TPH-g from previous quarters TPH-g concentration in this
<br /> well is at a historical high of 1,960 ppb
<br /> Diesel Hydrocarbons (TPH-d):
<br /> TPH-d in groundwater samples was measured using EPA Method 3510 TPH-d was detected
<br /> in 22 of 26 wells sampled (MW-1, 2, 3, 4, 5, 6, 8, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 21,
<br /> 22,23, T1, and T1) Detected TPH-d concentrations ranged from 519 ppb in Well MW-22
<br /> to 3,800 ppb in MW-8 TPH-d samples from Wells MW-1, 3, 5, 6, 10, 15, 20, 21, T-1, T-3
<br /> and WSW-1 were filtered using a glass TCLP filter(0 7- micron)prior to laboratory
<br /> extraction
<br /> Benzene:
<br /> Benzene in groundwater samples was measured using EPA Method 8020 Benzene was
<br /> detected in 7 of the 26 wells sampled (MW-1, 2, 3, 11, 15, 16 and 21) Detected benzene
<br /> concentrations ranged from 0 572 ppb in Well MW-21, to 604 ppb in MW-3 All seven
<br /> 1 benzene detections exceeded the MCL of 0 5 ppb for the first quarter
<br /> 1 MtBE:
<br /> MtBE in groundwater samples was measured using EPA Method 8020 MtBE was detected
<br /> in 12 of 24 wells sampled (MW-1, 2, 3, 4, 5, 8, 15, 16, 17, 18, 19, and 21) Detected MtBE
<br /> concentrations ranged from 5 19 ppb in Well MW-4, to 1,060 ppb in Well MW-2
<br /> CONCLUSIONS
<br /> Based upon the above data, PEG will continue to monitor the site on quarterly basis As
<br /> stated previously, PEG will attempt to sample and remove the stockpiled soils covering Well
<br /> MW-9 to enable sampling of this well dunng the third quarter
<br /> It is suspected that the elevated concentrations of TPH-d at this site are the result of
<br /> adsorption of diesel onto suspended particulates in the sample, not dissolved diesel in the
<br /> groundwater Therefore, in Wells MW-1, MW-3, MW-7, MW-15 and DE-5, where TPH-d
<br /> 920-002 2D/2Q98 DOC
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