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Upper A Zone
<br /> The 4Q05 groundwater monitoringresults for five monitoring wells MW-1 UA MW- -
<br /> g ( 38UA, MW 67UA, MW-
<br /> 69UA and EW-1), and the results of the 2003 grab-water sample collected from USB-2 were compared to
<br /> evaluate groundwater quality upgradient and downgradient of the former transmix UST location. The table
<br /> below summarizes the TPHd, TPHg, total BTEX, TBA, and MtBE concentrations reported for the 4Q05
<br /> monitoring event:
<br /> DistancetLocatio;n Relafâ–şve ,
<br /> tQ::.Former(LIST- TPFIc) , TPH °`',Tistal:BTEX ` TBA MtBE
<br /> MW-38UA 102 feet/Upgradient 83,000 89 <0.5 <5 <0.5
<br /> MW-69UA 40 feet/Upgradient 29,000 2,200 339 9 160
<br /> MW-1 UA 40 feet/Side radient 6,700 360 33 4,700 270
<br /> MW-67UA 60 feet/Down radient 5,200 11,000 2,550 60 29
<br /> EW-1 100 feet/Down radient 15,000 21,000 4,818 <50 7
<br /> USB-2' 1 150 feet/Down radient 2,100,000 230,000 57,900 140 5,300
<br /> Notes:
<br /> All results reported in pg/I.
<br /> -Results of a grab-water sample collected from soil boring USB-2 on 9/2/2003.
<br /> As summarized in the table above, and illustrated on the isoconcentration maps provided in Appendix B (i.e.;
<br /> Figures 6, 9, 11 and 13), these dissolved petroleum hydrocarbons are detected in the area of the former transmix
<br /> UST. However, these results are commingled with petroleum hydrocarbon impacts located upgradient of the
<br /> former UST(e.g.; MW-38UA located northeast of the loading racks) and downgradient of the former UST(e.g.;
<br /> USB-2 located between AST #131 and AST 4139), as indicated by the elevated concentrations at these two
<br /> locations.
<br /> The elevated concentrations of dissolved petroleum hydrocarbons reported for groundwater samples collected
<br /> from MW-69UA (located approximately 40 feet upgradient of the former transmix UST) in 4Q05 as
<br /> summarized above, suggest this well may be located within the area impacted by the former UST, given the low
<br /> horizontal gradient of the Upper A zone (i.e.; 0.003 ft/ft), or the existence of a possible upgradient source of
<br /> petroleum hydrocarbons.
<br /> A Zone
<br /> The 4Q05 groundwater monitoring results for three monitoring wells (MW-7A, MW-68A and MW-44A) were
<br /> compared to evaluate groundwater quality upgradient and downgradient of the former transmix UST location.
<br /> The table below summarizes the TPHd, TPHg, total BTEX, TBA, and MtBE concentrations reported for the
<br /> 4Q05 monitoring event:
<br /> Distance/Location Relative to Total
<br /> Well ID Former LIST TPHg TPHg', BTEX . TBA MtBE
<br /> MW-7A 170 feet/Upgradient 5,700' <50 <0.5 180 77
<br /> ' MW-68A Within UST Pit 5,000 <50 <0.5 <5 14
<br /> MW-44A 166 feet/Down radient 280 <50 <0.5 <52 <0.5
<br /> Notes:
<br /> All results reported in pg/l.
<br /> -TPHd results for MW-7A during 2Q05 and 3Q05 were>300,000 pg/I.
<br /> 2- Result for 2Q05, MW-44A not sampled for TBA during 4Q05.
<br /> BLASLAND,BOUCK &LEE, INC.
<br /> 3124106 engineers,scientists,economists 3-3
<br /> J:\D0006\44634_00161022_Conceptual Site Model.doc
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