ARCHIVED REPORTS 3RD QUARTER 2009 (1)

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exceedances are likely due, at least partially, to background groundwater quality conditions. In 3rd Quarter 2009 historical high concentrations were observed in wells KMW-1 (TDS, chloride), KMW-7 (sodium and chloride) and W-1 (TDS). However, because background water quality has not been defined, it cannot yet be concluded that these concentrations indicate significant groundwater quality changes. In addition to TDS, sodium, and chloride, the concentrations of the following constituents exceeded the interim limitations in one or more wells: • In the Third Quarter 2009, pH values exceeded the interim limitation in one of nine Crossroads wells (KMW-7). However, the pH value for well KMW-7 (8.68) was within its historical range. The pH levels in this well have been consistently outside the typical pH range of the treated wastewater, indicating that the pH exceedances are likely the result of background groundwater conditions. • Coliform bacteria are widespread in the environment and occur in large numbers within soil. The test for total coliform includes all coliform organisms, not just those found in the human intestinal tract. Historical total coliform counts have been variable and erratic from well to well and quarter to quarter. In the Third Quarter 2009, total coliform exceeded the interim limitations in two of the nine Crossroads wells. Although background coliform counts have not yet been defined for these wells, the background groundwater quality study performed at the nearby WRP-1 MBR plant would suggest that these exceedances are at least partially the result of background groundwater conditions. • Boron concentrations exceeded the interim limitations in seven of the nine Crossroads wells. All concentrations were within their historical ranges. Several Crossroads wells, including KMW-3 and KMW-7 located on Land Application Site 2, frequently exceeded the boron interim limitations even prior to the development and use of the sites. Therefore, most, if not all, of these exceedances are likely the result of background groundwater conditions. • Iron concentrations exceeded the interim limitations in three of the nine Crossroads wells (KMW-4, W-1, and MW-5). Iron concentrations in all wells were within their historical ranges. Although background iron concentrations have not yet been defined, the background groundwater quality study performed at the nearby WRP-1 MBR plant would suggest that these exceedances are at least partially the result of background groundwater conditions. • Manganese concentrations exceeded the interim limitations in eight of the nine Crossroads wells. Although background manganese concentrations - 14 -