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Mr Kyle Christie February 27, 1995 Page 2 r •r Results and Discussion Summaries of depth-to-water measurements and calculated groundwater elevations are presented in Table 1 Table 2 lists historical groundwater flow directions and hydraulic gradients for this site Analytical results of groundwater samples are-summarized in Table 3 The complete laboratory report for the sampling event is presented in Exhibit A Figure 2 shows TPH-G and BTEX concentrations for this sampling event The general groundwater flow direction beneath the site on December 8, 1994, was to the northeast under a hydraulic gradient of approximately 0 002 (Figure 1) Since groundwater monitoring began in 1989, the general groundwater flow direction has been to the northeast at this site The hydraulic gradient measured this quarter is within the range of previously reported gradients Depth-to-water on December 8, 1994 ranged from 14 99 in well BHD-1 to 17 73 in well E-11. Since the last quarterly monitoring event (September 29, 1994), water-level elevations in all monitoring wells except E-2, E-6, and MW-2 have increased an average of 0 39 feet The water level in well E-2 decreased 0 62 feet Water- level data collected from wells E-6 and MW-2 were not used in Figure i because the well casings were altered during the incorporation of each well into the soil vapor extraction and air sparging system. GTI's data are based on the altered well casings The well casing for these wells-will-be_resurveyed=in_the=first-quarter=of 1995 Benzene-concentrations=this=quarter_ranged-from-non=ddtectable inTwells E=7,E=12;PR=1, PR-2, BHD-2, and MW-1 to 3,300 micrograms -per liter_(µg11) in well E-10 - These concentrations are within the range of previously reported values TPH-G concentrations ranged from non-detectable in wells E-7, PR-1, PR-2, BHD-2, and MW-1 to 21,000 pg/1 in well E-3 These concentrations are consistent with previous values The detection limit for benzene is 0 5 pg/1 and for TPH-G is 50 pg/1 The hydrocarbon concentrations detected in BHD-1 are thought to be attributed to the Chevron station across the street from the ARCO site Chevron's well MWA is located approximately 30 feet to the north of well BHD-1 and near Chevron's former underground storage tank location Samples from Chevron's MW-1 have generally contained similar TPH-G and BTEX concentrations to those in BHD-1 Use or disclosure of data contained on this sheet is subject to the restriction specified at the beginning of this document ' 127"EPORT5\4TH94QTR RPT