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Mr. Robert McClellon
<br />July 9, 2008
<br />Page 3
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<br />the quarter ranged from 0% to 20.5%. Carbon dioxide concentrations measured at all sample locations
<br />ranged from 0.4% to 23.7%. Results for each probe, each extraction well, and each passive vent are
<br />summarized in Table 1.
<br />Groundwater. An interpreted groundwater contour map was prepared using the data collected on June
<br />10, 2008 (Figure 2). The groundwater flow direction is to the west at a gradient of 0.00065. For
<br />comparison, the groundwater flow direction varies from the southeast to the northwest (September 20,
<br />2007); varies from the west-southwest to the east-northeast (June 14, 2007, December 13, 2007 and
<br />March 13. 2008); from the southwest to the northeast (June 29, 2006, December 15, 2006 and March 14,
<br />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,
<br />selenium, and silver. The highest detected concentration of the remaining 13 metals are 0.189J
<br />milligrams per liter (mg/L) for aluminum (MW -1), 0.0285 mg/L for arsenic (MW -1), 1.25 mg/L for
<br />barium (MW -2), 0.00353J mg/L for chromium (MW -3),0.00849J mg/L for cobalt (MW -1), 0.00283J
<br />mg/L for copper (MW -2), 0.691 mg/L for iron (MW -2), 0.00549J mg/L for lead (MW -2), 4.40 mg/L for
<br />manganese (MW -1), 0.00998J mg/L for nickel (MW -1), 0.00538) mg/L for thallium (MW -1), 0.0189
<br />mg/L for vanadium (MW -3), and 0.0215 mg/L for zinc (MW -1). The highest TDS concentration of
<br />2,410 mg/L was found in MW -2. The field measurements for pH ranged from 7.00 to 7. 10, and specific
<br />conductance ranged from 1,800 to 3,350 micromhos (µmhos).
<br />Of the 13 reported metals constituents, primary maximum contaminant levels (MCLS) are established for
<br />eight 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 the DHS, barium at 2 mg/L by EPA and 1 mg/L by DHS,
<br />chromium [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,
<br />lead at 0.015 mg/L by EPA and DHS, nickel at 0.1 mg/L by DHS and thallium at 0.002 mg/L by EPA
<br />and DHS). For the remaining five metal constituents, secondary MCLS are established for three (iron at
<br />0.3 mg/L by EPA and DHS, manganese at 0.05 mg/L by EPA and DHS, and zinc at 5 mg/L by EPA and
<br />DHS). For one of the two remaining constituents, the California State Action Level for Drinking Water
<br />is established for vanadium at 0.05 mg/L. For the remaining constituent, the Agricultural Water Quality
<br />Limits is established at 0.05 mg/L for cobalt. Secondary MCLS are established for TDS at 500 mg/L by
<br />EPA and DHS and specific conductance at 900 µmhos by EPA. The dissolved metal results, TDS results,
<br />and the field measurements are summarized in Table 2.
<br />The analytical report is provided as Attachment 2.
<br />CONCLUSIONS AND RECOMMENDATIONS
<br />Thirteen metals (aluminum, arsenic, barium, chromium, cobalt, copper, iron, lead, manganese, nickel,
<br />thallium, vanadium and zinc) and TDS were detected above the analytical reporting limits in the
<br />groundwater samples collected on June 10, 2008. Of these constituents, five (barium, iron, manganese,
<br />thallium, and TDS) were above their established regulatory levels. Because four of the metal results and
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