ARCHIVED REPORTS_XR0007914 - Laserfiche WebLink

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TPH cleanup goal contained TPH less than 100 mg/kg In addition, soil samples collected as confirmation samples and located less than 10 feet laterally from S1-B1 did not contain TPH in excess of cleanup goals The extent of detectable concentrations of TPH and BTEX in ground ' water is limited to a localized area near the former UST These compounds have been detected only in ground water samples collected from monitoring wells MW-4 and MW-5, which are the two closest wells to the former UST location TPH and BTEX concentrations have decreased significantly since ground water monitoring activities began in April 1991 Furthermore, a significant decrease in TPH and BTEX ' concentrations appears to coincide with the soil removal activities performed in 1993, particularly for samples collected from MW-5 ' Samples collected from MW-4 during the last three sampling events contained no detectable TPH or BTEX concentrations If the area of petroleum-impacted soils were widespread, the area of ground water ' impacted by TPH and BTEX would likely be more laterally extensive and the concentrations higher than currently observed ' The data collected regarding the bacteria community in soil underlying the excavation are inconclusive as to whether the population would be sufficient to rapidly degrade petroleum hydrocarbons Former Tank Site #2 Review of soil chemical data collected during the investigative phase indicates that hydrocarbon products are not present at detectable 1 concentrations beneath the excavation backfill Some of the soil samples collected from a boring located along the excavation sidewall contained detectable concentrations of hydrocarbon products, ' however, the concentrations of TPH in these samples were significantly less than 100 mg/kg cleanup goal for TPH Therefore, the ' results of the 1994 post-excavation sampling activities support the 1993 confirmation sampling results that indicated that soils exceeding the TPH cleanup goal had been excavated. ' Review of soil chemical data collected from the soil boring located within the warehouse building indicates that hydrocarbon products are ' present in soil beneath the building at detectable concentrations Based on data collected during this investigation, soil containing TPH in excess of 100 mg/kg appears to be present in soils underlying the building within the interval of approximately 5 to 10 feet bgs In addition, TPH concentrations exceeding 100 mg/kg were detected in samples collected from a soil boring located along the office wall immediately adjacent to the former excavation area Elevated TPH 5-2