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4. Conclusions <br /> The purpose of this supplemental site investigation was to further define the extent of <br /> petroleum hydrocarbons in soil and groundwater in the vicinity of the former Cardlock Gas <br /> Station site Based upon this investigation, the following conclusions can be made <br /> • Groundwater flow direction continues to be toward the northeast across the <br />' site <br />' 0 Petroleum hydrocarbons were detected in groundwater samples collected <br /> from sampling locations SV 1 through SV7 downgradient from the former <br /> underground storage tanks (USTs) at the Cardlock station <br /> Petroleum hydrocarbons were detected in sod samples collected from SV 1, <br />' SV3, SV4, SV6, and SV7 located directly downgradient from the former <br /> USTs at the Cardlock site <br /> • Soils and groundwater samples collected from beneath the southeastern <br />' corner of the Venetian Square Shopping Center indicate the low level <br /> presence of petroleum hydrocarbons. <br /> • Because soil containing petroleum hydrocarbons exists only at depths <br />' greater than 23 feet bgs (within the capillary fringe zone), it appears that <br /> groundwater gradient and direction of flow were the primary factors which <br /> contributed to the offsite migration of petroleum hydrocarbons <br /> • Offsite soils have been impacted by petroleum hydrocarbons due to the <br />' forces of capillary tension These forces occur in the unsaturated zone, <br /> above the soil-groundwater interface, and cause the groundwater to be <br />' "wicked" or "drawn up" into the fine-grained sods. <br /> • Samples collected from Boring SV8 indicate that the former tank(s) at the <br /> Cardlock station are the likely source of the observed on site petroleum <br /> hydrocarbons Petroleum hydrocarbons released from the former Cardlock <br /> p�obIX9405481reportdoe 9 940549 00 <br />