Laserfiche WebLink
CLEARWAOTER <br /> C R O U •P, E N C <br /> 1.0 INTRODUCTION <br /> This report presents the results of groundwater monitoring performed by <br /> Clearwater Group, Inc (Clearwater) on March 13, 1995 at 4555 North Pershing <br /> Avenue in Stockton, California The location of the site is shown on Figure 1. The <br /> tasks performed during this phase of work included groundwater gauging, well <br /> Ipurging 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 This depth corresponds to <br /> the groundwater elevation seasonal maximum Three underground fuel storage <br /> tanks (USTs) one leaded gasoline, one unleaded gasoline and one diesel, were <br /> 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 MW-1 through MW-4 were installed along the perimeter of the former <br /> tank farm MW-5 was installed in the inferred downgradient direction Four <br /> groundwater monitoring events were subsequently performed by McLaren/Hart <br /> I Analytical results from these events indicate the presence of gasoline and/or BTEX <br /> compounds in samples collected from all the monitoring wells except MW-5 <br /> Benzene has been detected in groundwater samples collected from MW-2, MW-3 <br /> and MW-4 Concentrations of benzene have consistently been highest in MW-4 <br /> with a concentration of 400 parts per billion (ppb) in the sample collected in <br /> December 1994 <br /> I <br /> ID-103 QMR 1 4/21/95 <br /> I <br />