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I a= Harding Lawson Associates C. Conclusions About the Extent of Gasoline in soil and Ground Water Apporximately 2 gallons of floating product were bailed from MW-A and i MW-B, which are located in the gasoline tank backfill. During bailing operations, we were able to significantly decrease the amount of free product present in the wells. It appears that the quantity of gasoline that leaked .f into the backfill may be a relatively small. 1 Using the available test results, we conclude that significant concentra- tions of gasoline products have not migrated outside the tank backfill The TPP concentrations of 1100 ppm at 5.5 feet in MW-1 may represent an iso- lated condition and may not be related to the underground system. We believe the gasoline in the soil and water in MW-1 may have resulted from surface i„ spills being washed into the dry well or being carried by rain water runoff: It appears that .free product and significant amounts of dissolved gasoline � a are confined to the relatively pervious backfill in the immediate tank vicinity. The native site soils are relatively impervious and restrict lateral migration of ground water. The absence of gasoline in MW-2, MW-3; and � . g ? MW-4 indicates lateral spread of gasoline has not reached the site $ : boundaries.- r 3 The concentration of xylene in MW-1 is not a significant concern because 1 �- it is-far belo►� the--drinking water-action level recommended by the Department of Health Services. Neither benzene nor toluene was detected in any of the ! # water samples. We recommend that an additional monitoring well between KV-' and MW-2 be { installed to confirm that the leaked gasoline has not migrated oft site. An , 1 additional monitoring well is recommended because there is the possibility s 12 x .