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i 7-Eleven/Stockton 4 November 1989 -• 1986, five additional monitoring wells were installed (MW-5, MW-6, MW-7, MW--8, and MW-9) , and sampling of the monitoring wells and nearby domestic wells was initiated. These preliminary hydrogeologic investigations identified gasoline hydrocarbons adsorbed within the vadose-zone soil, dissolved within the groundwater, concentrated as separate-phase_ hydrocarbons (SPH) , and volatilized as vapors. : ; The discovery of SPH within MW-1 and MW-4 prompted the initiation of a groundwater remediation/abatement program. Initial work involved periodic hand bailing of SPH as requested by the San Joaquin Local Health District. In early July 1986, a , y small-diameter, double-pumping system was instdlled in MW--4 to control the continued migration of SPH and to collect SPH from the well. In an attempt to obtain increased control on the SPH and dissolved-phase hydrocarbc.n plumes beneath the site, three recovery wells (PW-1, PW-2, PW-3) were installed between October and November, 1986. A deeper, 12-inch-diameter recovery well (PW-3) was installed on-faite to replace the small-diameter monitoring well, MW-4, which had been used in the interim as an on-site recovery well. A 4-inch-diameter recovery well (PW-1) was also installed on the periphery of the site between MW-9 and the domastic well at 9135 Connie Avenue. Recovery 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 pzeviously installed MW-8. This pumping well was installed in the event that it would be needed to prevent the miqration of dissolved hydrocarbons toward domestic well 8968. It (PW-2) has never been used as a pumping well. GHI H:\IM XTF:H TECII\irLui;l'INC.