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MN 4 7-Eleven/Stockton February 1990 1986, five additional monitoring wells were installed (MW-5, MW-6, MW-7, M11-8, 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 free-floating separate-phase hydrocarbons (free product) , and volatilized as vapors. The discovery of free product in Mw-1 and MW-4 prompted the initiation of a groundwater remediation/abatement program. Initial work involved periodic hand bailing of free product as requested by the San Joaquin ]Local Health District. in early July 1986, a small-diameter, double-pumping system was installed in Mw to control the continued migration of free product and to collect it from the well. In an attempt to obtain increased control on the free -phase hydrocarbon plumes beneath the site, product and dissolved three recovery wells were installed between October and November, 1986. One 4-inch-diameter recovery well, PW-1, was installed an the periphery of the site between 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 the m 968. migration of dissolved hydrocarbons toward domestic well , It (PW-2) has never been used as a pumping well. A deeper, 12-inch--diameter recovery wel' (PW-3) was installed on to replace the 4-inch-diameter monitoring well, M11-4, which had been used in the interim as an on-site recovery well. _14 GROUND%VA7ER TECHNOLOGY,INC