ARCHIVED REPORTS XR0002714 - Laserfiche WebLink

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2.3. UNDERGROUND STORAGE TANK REMOVAL On 22 September 1998, two USTs, the dispenser island and associated piping were removed from the site. Four soil samples were collected beneath the USTs, one sample was collected beneath the dispenser area and three laboratory-compo sited soil samples were collected from the excavated soil and submitted for laboratory analysis_ MTBE and tertiary butanol (TBA)were detected in soil samples collected from beneath the USTs ' and dispenser island at concentrations up to 39 milligrams per kilogram (mg/kg); TPH-g was detected at concentrations up to 1,400 mg/kg; and benzene, toluene, ethyl benzene and xylenes (BTEX) were detected at concentrations up to 190-mg/kg. Approximately 200 tons of soil were excavated during removal of the Ts. After removal of the pp y g US USTs was completed, the soil was placed back into the excavation because of strong hydrocarbon odors and the proximity to a school. Two laboratory-composited samples were collected from the stockpiled soil prior to placement into the excavation. TPH-g,BTEX and MTBE and TBA were all detected in the composite samples. 2.4. SOIL EXCAVATION PROCEDURES On 10 November 1998,approximately 250 yards ofhydrocarbon-impacted soil were excavated from ' . the location of the former UST system using a backhoe with an approximate 15-foot reach capability. The excavated soil was stockpiled on the eastern edge of the site and field-screened for the presence of volatile organic compounds using an organic vapor meter(OVM). Subsequently, approximately 150 yards of soil was loaded and transported to Forward Inc. Landfill under manifest for proper disposal on 10 November 1999 and an additional 100 yards of impacted soil were transported to Forward Inc. Landfill for disposal on 14 December 1999. ' A total of nine soil samples were collected from the floor and sidewalls of the over-excavation for laboratory.analysis. TPH-g was detected at concentrations up to 80 milligram per kilogram(mg/kg) in the sample from the east end of the north wall of the excavation. TPH-g was not detect in soil samples collected from the south, northwest, and east wall of the over excavation. Additionally, TPH-g was not detected in the samples collected from the south end of the west wall and from the ' floor of the excavation. BTEX compounds were detected at concentrations up to 1.0 mg/kg; benzene was only detected in the north west wall sample. MTBE and TBA were detected at concentrations up to 1.3 mg/kg and 8.9 mg/kg, respectively; the highest concentrations of MTBE was detected in the northern portion ' of the over excavation, especially in the northern west wall sample (Tables 1 and 2). • 1`