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CAMBRIA 0 southern portion and eastern portion of the site did not contain detectable levels of petroleum hydrocarbons,thus providing lateral delineation to the south and east The most northerly boring (B-1) contained relatively low TPHg levels in soil Based on the location of the former service station site features, it is likely that petroleum hydrocarbon concentrations are lower north and west of boring B-1 Delineation of petroleum hydrocarbons in soil west of borings B-2, and B-3 was not possible since the City of Manteca dented us permission to drill either in the sidewalk or in the street Based on the location of the former service station site features, the relatively low levels of petroleum hydrocarbons detected in these borings, and the groundwater flow direction,it is Iikely that petroleum hydrocarbon-impacted soil does not extend much further west of these borings Based on the soil sampling analytical results, the vertical extent of petroleum hydrocarbons is defined No petroleum hydrocarbons were detected below 30 fbg t4'?(tAyvy'O' i°4 TBA was detected in Nl soil samples and in groundwater samples from two of the wells Based r� on the fact that the site was closed and the USTs were removed in 1983, and the fact that fuel oxygenates were not used in Shell gasoline until the early 1990's, it does not seem likely that the TBA detected is associated with the pre-1983 fuel release at this site Jot naCt55��1� The petroleum hydrocarbons detected in soil d groundwater in the B-3/GP-2 vicinity are defined downgradrent by well MW-5 J Pe eum hydrocarbons detected in B-1 and MW-3 are delineated by downgradrent well MW-4 Well MW-5 is generally located downgradrent of the GP-1/MW-1 vicinity, and provides lateral delineation of petroleum hydrocarbons from the GP-1/MW-1 area In summary34� J y�y3 • The vertical extent of petroleum hydrocarbon-impacted soil is delineated to less-than-30-ft, 0 The lateral extent of petroleum hydrocarbon-impacted soil is generally delineated, given the limited surface area available for investigation • The lateral extent of petroleum hydrocarbons in groundwater is defined by the wells along the eastern side of the site W e� en" i a, W&II e4s t r� mW -i. • The TBA detections are anomalous and are likely not associated with the fuel release at this i site • The groundwater flow direction is toward the east-southeast • 1660 6