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' Him Work,ng To Restore Nature Residual gasoline hydrocarbons (quantified as TPHg) were detected in soil samples at concentrations ranging from non detect to 5,100 parts per million Limits of TPHg at different ' depth intervals are shown on Plate 5 (Vapor Extraction Area of Influence for Soil 15 to 30 Feet Below Grade) and Plate 6 (Vapor Extraction Area of Influence for Soil 30 to 40 Feet Below Grade). Results of recent laboratory analyses are shown on Table 3, Results of Laboratory Analyses of Soil Samples Collected from Soil Borings B-14 through B-17. 1 4^2 Extent f H rbonjm acted Groundwater Results of subjective analyses of groundwater samples collected during the groundwater monitoring events indicated floating product has not been present at the site since monitoring began (Table 1). Laboratory results indicate that dissolved gasoline hydrocarbons are present ' in groundwater in the five onsite wells (MW-1 through MW-4, and RW-1). Concentrations of TPHg have ranged from below laboratory detection limits to 33,700 parts per billion (ppb) (well MW-1) while concentrations of benzene have ranged from below laboratory detection limits to ' 4,600 ppb (well MW-1) (Table 4, Results of Laboratory Analyses of Groundwater Samples) Concentrations of TPHg and benzene for September 28, 1994 are shown on Plate 7, ' TPHg/Benzene Concentrations in Groundwater (September 28, 1994). The analytical results are summarized in Table 4, Results of Laboratory Analyses of Groundwater Samples. ' 4.3 Depth to Groundwater During drilling, groundwater was encountered at approximately 37 feet bsg From December ' 1988 to September 1994, static water levels have fluctuated from approximately 30 to 45 feet bsg The variations in depth to water in the wells are apparently due to fluctuations associated ' with the natural groundwater cycle. Depth to water measurements are shown on Table 1 38009-8138009-8 FRP 10