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URS
<br />Mr. Robert McClellon
<br />January 14, 2009
<br />Page 3 of 4
<br />VP -1, 0.5% in VP -2,1.2% in VP -3, and 1.0 % in VP -4. Oxygen concentrations measured at all sample
<br />locations during the quarter ranged from 0% to 2 1. 1 %. Carbon dioxide concentrations measured at all
<br />sample locations during the quarter ranged from 0.6% to 23.3%. Results for each probe, each extraction
<br />well, and each passive vent are summarized in Table 1.
<br />Groundwater. An interpreted groundwater contour map was prepared using the data collected on
<br />December 9, 2008 (Figure 2). The groundwater flow direction is to the northeast at a gradient of
<br />0.00095. For comparison, the groundwater flow direction varies for the east-southeast to the west-
<br />northwest (September 10, 2008), from the east to west (June 10, 2008), from southeast to the northwest
<br />(September 20, 2007), from the west-southwest to the east-northeast (June 14, 2007, December 13, 2007
<br />and March 13. 2008), from the southwest to the northeast (June 29, 2006, December 15, 2006 and March
<br />14, 2007), and from the northeast to the southwest (September 29, 2006).
<br />The following metals were not detected above the analyses reporting limit: cadmium, mercury, selenium,
<br />silver and thallium. The highest detected concentration of the remaining 12 metals are 1.44 milligrams
<br />per liter (mg/L) for aluminum (MW -3), 0.0258J mg/L for arsenic (MW -1), 1.39 mg/L for barium (MW -
<br />2), 0.00451) mg/L for chromium (MW -3), 0.00796) mg/L for cobalt (MW -1), 0.00501J mg/L for copper
<br />(MW -3), 26.2 mg/L for iron (MW -2), 0.0823 mg/L for lead (MW -2), 4.77 mg/L for manganese (MW -2),
<br />0.0115 mg/L for nickel (MW -1), 0.0225 mg/L for vanadium (MW -3) and 0.0805 mg/L for zinc (MW -2).
<br />The highest TDS concentration of 2,520 mg/L was found in MW -2. The field measurements for pH
<br />ranged from 6.30 to 6.5 1, and specific conductance ranged from 1,870 to 3,540 micromhos (µmhos).
<br />Of the 12 reported metals constituents, primary maximum contaminant levels (MCLS) are established for
<br />seven constituents (aluminum at 1 mg/L by California Department of Health Services [DHS], arsenic at
<br />0.01 mg/L by EPA and 0.05 mg/L by DHS, barium at 2 mg/L by EPA and 1 mg/L by DHS, chromium
<br />[total] at 0.1 mg/L by EPA and 0.05 mg/L by DHS, copper at 1.3 mg/L by EPA and DHS, lead at 0.015
<br />mg/L by EPA and 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 2.
<br />CONCLUSIONS AND RECOMMENDATIONS
<br />Twelve metals (aluminum, arsenic, barium, chromium, cobalt, copper, iron, lead, manganese, nickel,
<br />vanadium and zinc) and TDS were detected above the analytical reporting limits in the groundwater
<br />samples collected on December 9, 2008. Of these constituents, seven (aluminum, arsenic, barium, iron,
<br />lead, manganese and TDS) were above their established regulatory levels. Because six of the metal
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