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7-Eleven/Stockton 4 August 1990 In order to initiate the assessment of the lateral and vertical extent of soil and groundwater impacted by gasoline hydrocarbons, groundwater-monitoring wells MW-1, MW-2, MW-3, and MW-4 were installed on May 6 and 7, 1986. In late May, 1986,, five additional monitoring wells were installed (MW-5, MW--6, MW-7, 11W-8, and MW-9) , and sampling of the monitoring wells and nearby domestic wells was initiated. These preliminary hydrageologic investigations identified gasoline hydrocarbons adsorbed within the vadose-zone soil, dissolved within the groundwater, concentrated as free-floating separate-phase hydrocarbons (free product) , and volatilized as vapors. The discovery of free product in monitoring wells MW-1 and MW-4 prompted the initiation of a groundwater-remediation/abatement program. Initial work involved periodic hand bailing of free d _ product as requested by the San Joaquin County Local Health District. In early July, 1986, a small-diameter, double-pumping system was installed in monitoring well MW-4 to control the continued migration of free product and to collect it from the well. In an attempt to obtain increased control over the free product and dissolved-phase hydrocarbon plumes beneath the site, three recovery wells were installed between October and November, 1986. One 4-inch-diameter recovery well, PW-1, was installed on the periphery of the site between monitoring well MW-9 and the �. domestic well at 9135 Connie Avenue. This well (PW-1) was installed to prevent the migration of dissolved hydrocarbons into domestic well 9135. Another 4-inch-diameter recovery well, PW-2, was installed downgradient and off site between domestic well 8968 and the previously installed monitoring well MW-8. This pumping well was installed in the event that it would be needed to prevent migration of dissolved hydrocarbons toward domestic well 8968. 14. GROUNDWATER TECEINOUKGY INC.