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URS
<br /> Mr. Robert McClellon
<br /> April 24, 2008
<br /> Page 3 of 4
<br /> RESULTS
<br /> Soil Vapor. The methane concentrations measured during the quarter in the gas-migration monitoring
<br /> probes were 1.6% in VW-6D. The methane concentration measured in the remaining probes (VW-1,
<br /> VW-2, VW-3, VW-4, VW-5S, VW-5D, VW-6S, VW-7S, VW-7D, VW-8S, VW-8D, VW-9, and VW-
<br /> 10)was 0%. The methane concentrations measured in the vapor extraction wells were 3.6%in EW-1 and
<br /> 9.1% in EW-2. The methane concentrations measured in the passive vents were 2.2% in VP-1, 5.4% in
<br /> VP-2, 7.8% in VP-3, and 7.1% in VP-4. The oxygen concentration measured at all sample locations
<br /> during the quarter ranged from 0% to 20.1%. The carbon dioxide concentration measured at all sample
<br /> locations ranged from 0.7%to 24.0%. The results for each probe, each extraction well, and each passive
<br /> vent are summarized in Table 1.
<br /> Groundwater. An interpreted groundwater contour map was prepared using the data collected on
<br /> March 13, 2008 (Figure 2). The groundwater flow direction is to the east-northeast at a gradient of
<br /> 0.0021. For comparison, the groundwater flow direction varies from the southeast to the northwest
<br /> (September 20, 2007), varies from the west-southwest to the east-northeast (June 14, 2007 and
<br /> December 13, 2007), from the southwest to the northeast (June 29, 2006, December 15, 2006 and
<br /> March 14,2007), from the northeast to the southwest(September 29,2006).
<br /> The following metals were not detected above the analyses reporting limit: aluminum, cadmium,
<br /> copper, lead, mercury, selenium, silver, and thallium. The highest detected concentration of the
<br /> remaining nine metals are 0.00926J milligrams per liter (mg/L) for arsenic (MW-1), 0.934 mg/L for
<br /> barium (MW-2), 0.00373J mg/L for chromium (MW-3), 0.00585J mg/L for cobalt (MW-1), 1.01 mg/L
<br /> for iron (MW-2), 3.98 mg/L for manganese (MW-2), 0.0108 mg/L for nickel (MW-1), 0.0173 mg/L for
<br /> vanadium (MW-3), and 0.0159 mg/L for zinc (MW-1). The highest TDS concentration of 2,140 mg/L
<br /> was found in MW-2. The field measurements for pH ranged from 6.49 to 6.78, and specific conductance
<br /> ranged from 1,700 to 3,260 micromhos(µmhos).
<br /> Of the nine reported metals constituents, primary maximum contaminant levels (MCLS) are established
<br /> for four constituents (arsenic at 0.01 mg/L by EPA and 0.05 mg/L by the California Department of
<br /> Health Services [DHS],barium at 2 mg/L by EPA and 1 mg/L by DHS, chromium [total] at 0.1 mg/L by
<br /> EPA and 0.05 mg/L by DHS,and nickel at 0.1 mg/L by DHS).For the remaining five metal constituents,
<br /> secondary MCLS are established for three (iron at 0.3 mg/L by EPA and DHS, manganese at 0.05 mg/L
<br /> by EPA and DHS, and zinc at 5 mg/L by EPA and DHS). For one of the two remaining constituents, the
<br /> California State Action Level for Drinking Water is established for vanadium at 0.05 mg/L. For the
<br /> remaining constituent, the Agricultural Water Quality Limits is established at 0.05 mg/L for cobalt.
<br /> Secondary MCLs are established for TDS at 500 mg/L by EPA and DHS and specific conductance at
<br /> 900 µmhos by EPA. The dissolved metal results, TDS results, and the field measurements are
<br /> summarized in Table 2.
<br /> The analytical report is provided as Attachment 3.
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