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Former Beacon Station No. 474 May 15, 2000 Stockton California Results of Additional Subsurface Investigation samples indicated TPHg concentrations of 2.3 and 1.1 ppm, respectively. The reporting limit for TPHg for these analyses was 1.0 ppm. Benzene was reported in the 50, 60, 80 and 100- foot samples at concentrations ranging from 0.0066 to 0.31 ppm. The reporting limit for benzene for these analyses was 0.0050 ppm. Xylenes were also detected in the 90-foot sample at a concentration of 0.013 ppm. No fuel oxygenates were reported in soil samples from soil boring B9. A concentration of 1500 ppb TPHg and concentrations of BTEX compounds ranging from 10 to 790 ppb were- reported for the hydropunch groundwater sample collected from soil boring B9. Methanol, MTBE and TBA concentrations of 63, 3.4 and 7.7 ppb, respectively, were reported for the hydropunch groundwater sample collected from soil boring B9; no other fuel oxygenates were reported in the groundwater sample. Results of soil analyses from the monitoring well MW-10 and MW-11 borings indicate delineation of gasoline constituents in site soil to the west and south of the dispenser islands. Results of soil analyses from the monitoring well MW-12 boring indicate gasoline constituent impacts from 30 to 112 feet bsg with the highest concentrations in the 30 to 85-foot interval. Results of soil analyses from the vapor well VW-7 and air sparge well AS-1 borings indicate gasoline constituent impacts generally from 60 to 90 feet bsg. Results of hydropunch groundwater and monitoring well sampling from soil borings B7, B8 and B9, monitoring wells MW-10, MW-11, MW-12 and air sparge well AS-1 indicate concentrations of TPHg and BTEX compounds in groundwater beneath the site. Concentrations of TPHg are currently reported in groundwater samples from monitoring wells MW-1 and MW-9 south of the dispenser islands, and monitoring well MW-10 west of the dispenser islands. Benzene concentrations in groundwater appear to extend just west of monitoring well MW-10 and south of monitoring well MW-11 as shown on the benzene isoconcentration map (Figure 3). The extent of gasoline constituents in groundwater is effectively delineated to the north, east and southeast by monitoring wells MW-5, MW-8 and MW-7, respectively. The extent of benzene in groundwater is effectively delineated to the west and south by monitoring wells 1474.22rpt 8 HORIZON ENVIRONMENTAL INC.