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r ! Y l <br /> 26 March 1999 <br /> AGE-NC Project No 98-0426 - <br /> r <br /> Page 5 of 6 <br /> i <br /> [ S <br /> in probing B1; advanced at the former OsTs location'Organic vapor was not detected in , <br /> Isamples collected from depths of,15 and 20 feet bsg in probing Bl The vertical extent of <br /> impacted soil beneath the former USTs appears to be lunited between 10 to 15 feet bsg , <br /> I • -Petroleum hydrocarbons were detected in soil samples collected from probing B3, advanced <br /> near the western dispenser island location at concentrations as high as 3,700 ppm 1, 1 ` <br /> • Petroleum hydrocarbons were not detected in soil samples collected at depths greater than , <br /> 30 feet bsg The vertical extent of impacted soil has been defined at the site <br /> • Petroleum hydrocarbons were not detected in soiI samples analyzed from probings B 1, B2, <br /> I B4, B5 and B6 The lateral extent of impacted soil has been defined at the site <br /> y ., w E t f , t ri . <br /> • Ground water was measurdd at a depth of 23 feet bsg dunizg advancement of soil probe <br /> Iborings at the site t N <br /> • TPH,g was detected at a concentration of 12,000 ppb in the grab water sample collected from w <br /> Iprobing B3 Benzene and toluene were not detected in this sample <br /> • TPH-g was detected at concentrations of 250 ppb and 220 ppb in grab water samples <br /> • collected from probings B 1 and B5 BTEX were detected in the water sample collected from <br /> B1 Hydrocarbons,were not detected in water samples collected from probings B2, B4 and <br /> B6 The concentration of benzene detected in the water sample collected from B 1 exceeds <br /> the State of California drinking water Maximum Contaminant Level (MCL) of 1 ppb <br /> a � Y , <br /> Impacted soil and ground water appears to be centered at the western dispenser island <br />' Higher concentrations of volatile aromatics(BTEX) were detected in-the grab water sample <br /> collected from probing 131, located in,the presummed down-gradient direction,from the <br /> dispenser island The lighter hydrocarbon constituents appear to have°migrated toward the <br /> i northeast � I i <br /> ` <br /> '' <br /> r ' <br /> 6.0. ,RECOMMENDATIONS <br /> Based`upon data collected`from the site, 'AGE recommends continued assessment of,impacted <br /> ground water at the site A work planshould be prepared for the installation,of ground water <br /> morntorng wells-to define the lateral extent-of impacted ground water and determine a site-specific <br /> Iground water gradient <br /> T1 <br /> r , <br /> nf, Advanced GeoEnvironmental,Inc <br /> r <br /> r f 5 h <br />