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GEOMATRIX collected from a trench at 14 feet bgs that contained 0.32 mg/kg of TCE (WHF, 1996). TCE was analyzed in the 5 and 10 feet bgs samples collected from GMX-1B and was not detected. 2.2.2 Groundwater Conditions Based on historical and more recent water level measurements, groundwater is encountered between approximately 30 and 35 feet bgs and the horizontal flow direction is to the northeast. Historical groundwater investigations included the installation and initial sampling of monitor- ing well MW-1 in 1996 by Geological Technics (GTI, 1996) and installation and initial sam- pling of monitoring wells MW-2, MW-3, and MW-4 by Radian in 1998 (Geomatrix, 20001). Groundwater sampling activities also included the collection of grab groundwater samples from locations downgradient and in the vicinity of well MW-1. Grab groundwater samples were collected from three CPT borings (CPT-1, CPT-2, and CPT-3) advanced adjacent to MW-1 by Radian in 1997 and from one direct-push boring (GMX-6) advanced off-site by Geomatrix in 1999 (Geomatrix, 2000). Groundwater has also been sampled from an existing off-site moni- toring well (WSFMW-1)by Geomatrix in 1999 and 2002 (Geomatrix, 2000, 2002a). Petroleum hydrocarbon constituents have been detected in on-site monitoring wells MW-1, MW-2, and MW-3. A thin layer of separate-phase petroleum has been observed in MW-1 and MW-2 . The separate-phase petroleum observed in MW-1 and MW-2 is likely responsible for elevated concentrations (>1000 ug/L) of total petroleum hydrocarbons (TPH) quantified as gasoline (TPHg) and/or TPH quantified as diesel (TPHd)reported for the samples collected from MW-1 and MW-2 (Table 2) due to petroleum entrained in the samples as opposed to dis- solved concentrations of petroleum constituents in groundwater. TPHd has been detected in groundwater samples collected from MW-3. No petroleum constituents have been detected in on-site well MW-4 and off-site well WFSMW-1. Additionally, on-site production well W-1,which reportedly has been used for facility water, was tested for volatile organic compounds (VOCs), including benzene, toluene, ethylbenzene, and xylenes (BTEX), in 1995 and 1996; no compounds were detected and the well water met applicable drinking water standards (ERM, 1995a; GTI, 1996). Concentrations of VOCs (i.e., BTEX and cis-1,2-DCE) in groundwater samples collected from the CPT borings located within the estimated area of petroleum impacted soil were less than the Results of groundwater samples collected by Radian International LLC in 1998 were reported in Geomatrix's February 2000 Soil and Groundwater Investigation Report. I:\Doc_Safe\6000s\6447.001\OffSite Rpt\US Can SoilGW Rpt 2003.doc 4