Waste Area Group 10, Operable Unit 10-08, Annual Monitoring Status Report for Fiscal Year 2009

This report documents the status of Fiscal Year 2009 groundwater monitoring performed in Waste Area Group 10 at the U.S. Department of Energy Idaho National Laboratory Site, as identified in the Groundwater Monitoring and Field Sampling Plan for Operable Unit 10-08. Twelve of the fourteen required wells were sampled, and all ten required intervals from the Westbay wells were sampled. Two wells were not sampled because they were in the process of being converted into multiple-sample-interval Westbay wells by the U.S. Geological Survey. Groundwater samples were analyzed for volatile organic compounds identified on the Contract Laboratory Program target analyte list as well as metals (filtered), anions, and radionuclides (i.e., I-129, tritium, Tc-99, gross alpha, gross beta, and Sr-90). No contaminant exceeded maximum contaminant levels in wells along the southern boundary of the Idaho National Laboratory Site or in guard wells. Iron was above its secondary maximum contaminant level of 300 ug/L in one well. The cause of the elevated iron concentration is uncertain. Lead was detected just below its action level. However, the zinc concentration was also elevated in these wells, and the source of the lead is probably galvanized riser pipe in the wells. Once the galvanized pipe is replaced, both lead and zinc concentrations should decline, as has been observed at other Waste Area Group 10 wells.