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URS Mr. Robert McClellon January 31, 2011 Page 3 RESULTS Survey. The vertical elevation of the three monitoring wells was resurveyed during the repairs of monitoring well MW-1. The resurveyed vertical elevation of the top of the well casing for MW-1 (prior to repair),MW-2,and MW-3 were 12.33, 11.32, and 14.39 feet North American Vertical Datum of 1988 (NAVD88), respectively. The resurveyed vertical elevation of the top of the well extension for MWA (after repair)was 12.53 feet NAVD88. Soil Vapor. The methane concentrations measured during the quarter in the gas migration monitoring probes were zero percent in all probes. Methane concentrations measured in the vapor extraction wells were 2.4% in EW-1 and 0.2% in EW-2. Methane concentrations measured in the passive vents were 0.2% in VP-1, 1.0% in VP-2, 1.5% in VP-3, and 1.0% in VP-4. Oxygen concentrations measured at all sample locations during the quarter ranged from 0%to 20.9 percent. Carbon dioxide concentrations measured at all sample locations during the quarter ranged from 0.3%to 22.9 percent. Results for each probe, each extraction well, and each passive vent are summarized in Table 1. Groundwater. Because the top of groundwater monitoring well MW-1 was damaged,an interpreted groundwater contour map was not prepared for the 3Q10 quarterly monitoring report. Using the resurvey vertical elevation data of the three groundwater monitoring wells, an interpreted groundwater contour map was prepared using the data collected on September 14,2010(Figure 2)and on December 16, 2010(Figure 3). The groundwater flow direction for the September 14,2010 and the December 16, 2010 data are to the west-northwest at a gradient of 0.0024 and to the east-northeast at a gradient of 0.0020,respectively. The groundwater flow direction results can be compared to the historical results. The predominant groundwater flow direction of the previous quarterly monitoring events is shown to be in the southwest to northeast or west-southwest to east-northeast direction but has varied from quarter to quarter. The following eight metals were not detected above the analyses reporting limit: aluminum,cadmium, copper, lead,mercury, selenium, silver,and thallium. The highest detected concentration of the remaining nine metals are 0.115 milligrams per liter(mg/L) for arsenic (MW-1), 1.19 mg/L for barium(MW-2), 0.00444J mg/L for chromium(MW-3), 0.00374)mg/L for cobalt(MW-2), 9.03 mg/L for iron(MW-2), 3.39 mg/L for manganese(MW-2), 0.00843J mg/L for nickel(MW-2), 0.0186 mg/L for vanadium(MW-3),and 0.00787J mg/L for zinc (MW-1). The highest TDS concentration of 2,270 mg/L was found in MW-2. The field measurements for pH ranged from 6.81 to 7.01,and specific conductance ranged from 1,800 to 3,450 micromhos(µmhos). Of the nine reported metals constituents, primary maximum contaminant levels(MCLs)are established for four constituents(arsenic at 0.01 mg/L by EPA and 0.05 mg/L by California Department of Health Services [DHS],barium at 2 mg/L by EPA and 1 mg/L by DHS,chromium [total] at 0.1 mg/L by EPA and 0.05 mg/L by DHS, and nickel at 0.1 mg/L by DHS). For the remaining five metal constituents, secondary MCLs are established for three(iron at 0.3 mg1L by EPA and DHS, manganese at 0.05 mg/L by EPA and DHS and zinc at 5 mg/L by EPA and DHS). For the two remaining constituents,the H:\Wprocess\25532\WorldEnterprise\Quarterly Rpt\2010\4Q10\01201 Ldoc