ARCHIVED REPORTS_XR0004945 - Laserfiche WebLink

Home Browse Search

i Ihydrocarbons as gasoline and diesel (TPH-g and TPH-d),benzene, toluene, ethyl benzene and total • xylene,(BTEX) and fuel additives In the soil samples collected from the UST excavations and dispenser areas, the latter exhibited significant staining and hydrocarbon odor IPREVIOUS SITE ASSESSMENT On 11 August 1999, an additional 150 cubic yards of significantly petroleum-Impacted soil was ' removed from the beneath the three former dispenser areas Laboratory analytical data Indicated a significant concentration ofTPH-g,TPH-d,BTEX compounds and fuel additives in the soil samples collected On 29 October and 01 November 1999 AGE advanced eight soil robe bona s to a depth of 30 feet 1� p g P ' bsg at the site to obtain soil and grab ground water samples TPH-g,TPH-d,BTEX and methyl tert- butyl ether (MTBE) were detected in soil samples analyzed at maximum concentrations of 49 milligrams per kilogram(mg/kg), 180 mg/kg 0 36 mg/kg,and 78 micrograms per kilograms(ug/kg), ' respectively Laboratory analysis of grab ground water samples Indicate that the highest concentrations of TPH-g,TPH-d,BTEX and MTBE were In the vicinity of former dispenser Islands Based on the data collected,the dispenser Islands appear to be the primary source of the hydrocarbon Irelease Ground water monitoring wells MW-1 through MW-5 were installed On 27 and 28 September 2000 and monitored and sampled on 03 October 2000 TPH-g and TPH-d compounds were detected in in nll fay only one of eleven soil samples, at similar concentrations of 170 mg/kg , in addition, BTEX` '"q MOL several additional volatile organic compounds were detected at concentrations up to 0 44 mg/kg 4r►5 ' TPH-g, TPH-d and BTEX was detected Int o o ground water samples collected on 03 October 2000 00 at maximum concentrations of gg/I,2-,6Wgg/l, and 160gg/l respectively,In addition,MTBE was detected In three ground water samples at a maximum concentration of 170 pgl /4 p,c�IL,1V md'krwl��d On 09 December 2003, three soil borings (CPT-1, CPT-2, and CPT-3) were advanced on site ' utilizing CPT technology to a total depth of approximately 110 feet bsg At each boring location, hthologlc data was collected from the initial CPT boring, an Immediately adjacent twin boring was then advanced to collect grab groundwater samples CPT-1 was sampled between 55 feet and 60 feet ' bsg and between 80 feet and 84 feet bsg, CPT-2 was sampled between 55 feet and 60 feet bsg, between 89 feet and 94 feet bsg and between 110 feet and 114 feet bsg, and CPT-3 was sampled between 55 feet and 60 feet bsg,between 85 feet and 90 feet bsg and between 110 feet and 114 feet ' bsg ' HYDROGEOLOGICAL MODEL Based on the CPT results, AGE has assigned names to four Informal zones, a vadose(unsaturated) ' zone and three hydrogeologlc units Vadose Zone-Extending from surface grade to approximately 15 feet bsg, the depth to the water table The vadose zone Is predominantly fine grained material ' Advanced GeoEnvironmentak,Inc 1