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t <br /> CLEAWATER <br /> G R O U P, I N C <br /> En=eronneentul Services <br /> 1.0 INTRODUCTION <br /> This report presents the results of groundwater monitoring performed by <br /> Clearwater Group, Inc. (Clearwater) during the second quarter of 1996 Groundwater <br /> monitoring was conducted on June 19, 1996 at 4555 North Pershing Avenue in <br /> Stockton, California (Figure 1) The tasks performed included groundwater gauging, <br /> well purging and groundwater sample collection <br /> 2.0 BACKGROUND <br /> The site is currently unoccupied and is principally utilized as a two-lane driveway <br /> providing access to an adjacent shopping center (Figure 2) It was formerly operated <br /> as a cardlock refueling station <br /> Previous investigations have been performed at the site by TreaTek, Inc , TMC <br /> Environmental, Inc (TMC) and McLaren/Hart Nine soil borings were drilled by <br /> TMC to a maximum depth of 31 feet below grade surface (bgs) in June 1991 Analysis <br /> of soil samples collected from the borings indicated the presence of gasoline <br /> contamination at a depth of approximately 25 feet bgs Three underground fuel <br /> istorage tanks (USTs) containing leaded gasoline, unleaded gasoline, and diesel fuel <br /> were excavated and removed from the site by TreaTek, Inc, on January 8, 1992 <br /> On November 3 through November 5, 1992, McLaren/Hart installed five <br /> groundwater monitoring wells, MW-1 through MW-5, to a maximum depth of 40 <br /> feet bgs (Figure 2) MW-1 through MW-4 were installed along the perimeter of the <br /> former tank farm and MW-5 was installed in the inferred downgradient direction <br /> (Figure 3). Four groundwater monitoring events were subsequently performed by <br /> McLaren/Hart between November 1992 and December 1993 Samples were analyzed <br /> for total petroleum hydrocarbons as gasoline (TPHg), as diesel (TPHd) and as motor <br /> oil (TPHmo), as well as for fuel constituents benzene, toluene, ethylbenzene and <br /> total xylenes (BTEX) <br /> Clearwater began quarterly groundwater monitoring and sampling at the subject <br /> location in December 1994 All field work has been conducted according to <br /> Clearwater Field Procedures (previously submitted) which are consistent with both <br /> local and state guidelines <br />• <br /> D-103 2Q96 1 July 11,1996 <br />