ARCHIVED REPORTS_XR0007914 - Laserfiche WebLink

Home Browse Search

SECTION 5 1 INTERPRETATION OF DATA 1 ' ' The following section interprets the results of the additional soil investigation and ground water monitoring at Former Tank Sites #1 and #2 Former Tank Site #1 Review of soil chemical data collected during the investigative phase indicates that hydrocarbon products are not present at detectable concentrations beneath the building but are present beneath the excavation backfill It appears that soil containing TPH in excess of ' the 100 mg/kg cleanup goal and benzene in excess of the industrial PRG is present at the S1-B1 boring location immediately below the base of the excavation backfill from approximately 8 to 10 feet bgs Review of ERM field observations made during the 1993 excavation activities indicates that excavation in the suspected area of hydrocarbon impacted soils was discontinued due to excavation instability caused by ground water seepage The elevated TPH concentration detected during the 1994 post-excavation sampling activities is likely indicative of a minor amount of residual hydrocarbon-impacted soils that may have been left below the water table during the 1993 excavation activities Therefore, the results of the 1994 post-excavation sampling activities are not inconsistent with the 1993 confirmation sampling results that indicated ' that the majority of the TPH-affected soils (i e , those exceeding the TPH cleanup goal) had been excavated ' Support for the interpretation that the hydrocarbon-impacted soils are localized in the immediate area of the former tank at Site #1 is as follows ' • The TPH-impacted interval is relatively thin (less than 2 feet thick), and ' • Ground water quality does not appear to be negatively affected TPH and BTEX concentrations in samples collected from boring S1-B1 rapidly decrease with depth below the excavation backfill A soil sample collected less than 15 feet below the sample that exceeded the 5-1