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CLEARWATER <br /> G R O U P I N C <br /> 1.0 INTRODUCTION <br /> This report presents the results of groundwater monitoring performed by <br /> Clearwater Group, Inc (Clearwater) on June 8, 1995 at 4555 North Pershing Avenue <br /> in Stockton, California The location of the site is shown on Figure 1 The tasks <br /> I performed during this phase of work included groundwater gauging, well purging <br /> and groundwater sample collection <br /> 2 0 BACKGROUND <br /> The site (Figure 2) is currently unoccupied and principally utilized as a two-lane <br /> driveway providing access to an adjacent shopping center 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 /> storage tanks (USTs) one leaded gasoline, one unleaded gasoline and one diesel, <br /> were excavated and removed from the site by TreaTek, Inc , on January S, 1992 <br /> I 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) Analytical results indicated the presence of TPHg and/or BTEX <br /> in samples collected from all monitoring wells except MW-5 Benzene was detected <br /> in groundwater samples collected from MW-2, MW-3 and MW-4 <br />' 3.0 FIELD ACTIVITIES <br />' Clearwater began quarterly groundwater monitoring and sampling at the subject <br /> locations 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 /> D-103 QMR 1 July 11,1995 <br /> I <br />