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<br /> 28-November 2401 r k,t F
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<br /> AGE-NC Project No:96-0229
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<br /> Page 5 of 6 f -
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<br /> 3.0. SUMMARY AND CONCLUSIONS � .q _ • ,�, -�
<br /> The Implicatloiis of the duly 2001 CPT investlgatiori-results- as,follows . = .
<br /> .. AGE interprets the--CPT data to;;identify.ahree potential..ligeologic units Informalldroy:.. 1
<br /> k identified as."First.Water Zone'' �'loeated 25 to'45,feet bs ,."Second.Water Zone" located
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<br /> T - -A60 to.75 feet bsg)'arid•-"Third Water Zone';-(located 80.to at least l00 feet bsg).=Second Water`= }=-`
<br /> Zone and Third Water Zone-appear to have vertical communication wesf of the UST pit due i
<br /> . to'thinriiiig or`absent fine-'gamedvunits and It is not known how effectively Intervening fine
<br /> : . _grained intervals hydrologically separate the inforrrlal liy rogeologi.c units Geologic cross
<br /> 'sections C-C'andP-D'were generated from-CPT data=collected from P _10,P -f'1;P'- 2' -P-43:`
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<br /> ..and P=1.4 and depict gene beneath_the'site ' cross sectional view(Figures 3 and
<br /> Permeable litholo consistin of avell , fine toycoarse sand was comnonl encountered .? Y r
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<br /> at.depths between,30-and'40 feet bsg{First Water Zane), 70 and 75 feet bsg-(Seeond:�Water 71
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<br /> "Zone) $S and at leash 100 feet bs Thir_d Water.Zone . Conversel less- ermeable fine:"
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<br /> wined sit cla and cla. a silt-was ericouritered.at d the between 1 and.S:.feetbs (above.
<br /> First,Water,Zone), 50.and.60 feet bsg (transition between First and Seeand'Water Zones),
<br /> ` 75 and 84 feet bsg(transition between Second and-Third Water Zones and between.=95 feed r max_
<br /> ' T and 100.feet bsg(below Third-Water Zone) 'Variable.lithology,.lncluding silty.fine and and'
<br /> - sandy silt, was observed at:_all other depths (Figures 3 and 4J
<br /> f Dissolved constituents 'o"f-concern detected at P 11 F 12-and P=14 Were,TPH g,;BTEX, : _ "y
<br /> MTBE and 1;2-DCA(Table 1)and have pieviously.been detected'in ground water samples *
<br /> collected at.monitoring wells at the-site, Constituents of concern.detected it, Fiisi Water
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<br /> r s ,-Zone;'Second-Water Zone-and Third Water Zone are depicted by informal-hydrogeologic 7
<br /> units Iii cross.sectlonal'views C-C'and D D'.(Flgures 5 and 6, respectively) , _ k
<br /> x r" First "Water Zone fuel-impact-at the-site includes TPH=g; BTEX and MTBE;:fiirther .Y
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<br /> downgradient, approximately 280 feet towards the north northeast (downgradient) at P 14,
<br /> x substantial TPH-g'
<br /> ;:BTEX"MT13E and'l';2-DCA coiistifueilt!-were deteci d,'the greatbst.Frrst"
<br /> t = =Water Zone fuel Irnpact has been_-reported from-monitoring wefils MW.-I,,MW 2,MW 3,
<br /> y'MWand soil'borings P-1, P-2 and P-11 The estimated ex tent TofFarst<-Water Zori'e fuel-
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<br /> impact is depicted roll ur"e 7 f
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<br /> Second YYater Zone fuel impact at.the site includes low concentrations of BTEX constituents <_ w.
<br /> detected,a_t P`l 1,MTBE and 1,2-DCA were detected at'P 14'The estimated extent of Second- 4
<br /> TWater..Zone'fuel Impact is depicted m Flgure,8:
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<br /> 1 . -• `Third Water.-Zone fuel Impact atahe site Includes TPH garid BTEX col shtuents detected ;-
<br /> at P; 11 and`,P-12 The estimated extent of;Third Water
<br /> ter -Zonedepicted m -
<br /> r, 7 _;•Figure 9.
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