Laserfiche WebLink
' Site Background Information Five Star Marina <br /> 10 Page 7of8 <br /> of approximately 15 feet bsg, at which point the contaminants encountered a more porous sandy <br /> unit and began to migrate laterally as well as vertically, the direction of lateral migration appears <br /> to be toward the northeast, in the preferred ground water flow direction The vertical migration <br /> of soil contamination appears to be slowed by the silty and clayey layer encountered below the <br /> ' sand unit, and by the fat clay layers identified at varying depths beginning at approximately <br /> 23 feet bsg At the location of boring Bl, a low concentration of TPH-g (3 4 pg/l) was detected <br /> in the thin sandy layer encountered at 30 feet bsg, located directly below a fat clay layer, <br /> however, no petroleum hydrocarbon constituents were detected in BI in a soil sample collected <br /> at 35 feet bsg <br /> ' Contamination was detected in January 2006 in a grab ground water sample collected at 10 feet <br /> bsg in soil boring B 1, located slightly east (down-gradient) of the former west UST area, ground <br /> ' water samples collected from monitoring well MW-I, located approximately 12 feet northeast of <br /> boring B 1, have been consistently impacted with elevated (yet decreasing) concentrations of <br /> TPH-g and BTEX constituents Ground water in monitoring well MW-3, located 40 feet <br /> ' northeast of MW-1, has typically remained uncontaminated TPH-g was detected in a grab <br /> ground water sample collected at 10 feet bsg from up-gradient boring B2, however, this <br /> detection is probably due to the intrusion of a contamination plume from tate adjacent western <br /> property <br /> F.4 STER IV DI ST RF[I,',1 SF, -I ivl) ivlt7,R14 TION <br /> ' The castcrn US-I-, a dispenser, and associated product line', wcrc, icmoved from the site on <br /> 18 November 1997, holes were noted at the western end and iii the bottom of tl}e UST <br /> ' Hydrocarbon odors were not observed in soil above I I feet bsg Analytical results of soil <br /> samples collected frorn the LST excavation indicated that an unauthorized release of <br /> hydrocarbons had occurred at the western edge of the UST and/or the. dispenser area, as soil <br /> ' samples collected at 10 feet bsg near the dispenser were severely impacted (P21-10 and P22-10, <br /> Table 1) Contaminants were released into a lens of sandy material encountered between depths <br /> of approxiinately 8 feet and 12 feet bsg, at which point they appear to have undergone a lateral <br /> tmigration southeast of the US1" <br /> Although the preferred direction ofground water flow in the. aria is toward the northLast ground <br /> ' ',vales gradient and flow direction data in the east LST area have only been collected since the <br /> January 2006 ground water monitoring event, data collected during this CVLnt indicated an <br /> atypical southern trend ni now direction in both the east and west U5T areas suggesting III& the. <br /> ' focal giadiL nt may bL ,indb]L and subjcL[ to influtnLL from surfacL �GatL.r elevation changes and <br /> tidal effects in the 51oLk[(1n 17cL11 \Vater C hannel, Jocatcd approminatcly 230 fc _t south cif til L. <br /> cast t:S 1- area <br /> ' l_oiE 'tilt LUsLUn LJST', soL thcast-5 i <br /> p eading shallow pliurie contaminants migrated through 'nc <br /> 11"�L f'Ilii1('� f'� i���v f1i!t� � ,�, LCf'ti 1'Ll(11� fh,, tiii1C1� ] _tis �.L) ; rliticaf Cli"pth (�� i]lf�i'l�i«l]fi 't <br /> 1 1 <br /> frliir<<<I{: ni•ri iii iijEi� f <br />