ARCHIVED REPORTS_XR0003068 - Laserfiche WebLink

Home Browse Search

1 T ' 11 November 2004 AGE-NC Project No 99-0624 ' Page 2 of 13 ' 2 2 UNDERGROUND STORAGE TANK REMOVAL Three 10,000-gallon USTs were removed from the site in June 1998 and replaced with three new ' 10,000-gallon gasoline USTs Soil samples were collected from beneath each UST,dispenser Island and from the excavated soil and analyzed for total petroleum hydrocarbons quantified as gasoline (TPH-g), volatile aromatic compounds (benzene, toluene, ethylbenzene and total xylenes BTEX), ' fuel oxygenating compounds (MTBE, tertiary-amyl methyl ether [TAME], di-isopropyl ether [DIPE], ethyl tertiary-butyl ether [ETBE] and tertiary-butyl alcohol [TBA]) and total lead in accordance with the appropriate EPA Methods ' No TPH-g or BTEX compounds were detected in soil samples collected beneath the former USTs or dispenser island However, MTBE and TBA were detected beneath the south ends of UST Nos ' 2 and 3 at concentrations as high as 9 8 milligrams per kilogram(mg/kg)and 31 mg/kg,respectively, MTBE and TBA were detected beneath the north end of UST No 3 at concentrations of 0 48 mg/kg and 0 9 mg/kg,respectively Xylenes were detected at 0 012 mg/kg in one sample collected beneath ' the former dispenser island Low concentrations of xylenes were also detected in samples collected from the excavated(stockpiled) soil The stockpiled soil was transported off-site for disposal with approval from the San Joaquin County Environmental Health Department (SJCEHD) I23 PREVIOUS SUBSURFACE INVESTIGATION The following is a brief summary of site assessment activities ' March 1998- Four soil borings (B 1 through B4) were advanced to maximum depths of 25 feet below surface grade (bsg) near the three former 10,000-gallon USTs and former fuel ' dispenser Island areas TPH-g and BTEX compounds were not detected in any of the analyzed samples, however,MTBE was detected from soil boring B 1 at 20 feet bsg near the northeast end of the former USTs at a concentration of 0 25 milligrams per kilogram A letter of findings (Analytical Results of Pre-removal Assessment, dated 25 March 1998) was submitted by AGE to the SJCEHD • September 1999 - Three soil borings (P-1 through P-3)were advanced to maximum depths of approximately 60 feet bsg near the former UST and fuel dispenser Island areas TPH-g was detected in the 50-foot soil sample from P-1 at a concentration of 2 6 mg/kg, low ' concentrations ofBTEX compounds were detected from P-1 between 45 feet and 55 feet bsg at concentrations as high as 0 16 mg/kg Significant MTBE was detected from P-1 at depths between 25 feet and 55 feet and from P-2 at 25 feet bsg at concentrations as high as 3 8 mg/kg(P1-25) Laboratory analysis of a grab water sample collected from P-1 detected TPH-g at 1,500 micrograms per liter(µg/1), BTEX compounds as high as 690 µg/1 benzene and MTBE at 420µg11 A report of findings(Preliminary-Investigation&Evaluation Report, IAdvanced GeoEnvironmentai,Inc