First Quarter 2005
INL Quarterly Site Environmental Report
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The ESER program samples precipitation, surface water, and drinking water. Monthly composite precipitation samples are collected from Idaho Falls and the Central Facilities Area (CFA) on the INL. Weekly precipitation samples are collected from the Experimental Field Station (EFS) on the INL. Surface and/or drinking water are sampled twice each year at 19 locations around the INL. This occurs during the second and fourth quarters. A summary of approximate minimum detectable concentrations (MDCs) for radiological analyses and DOE Derived Concentration Guide (DCG) (DOE 1993) values is provided in Appendix B.
Precipitation samples are gathered when sufficient precipitation occurs to allow for the collection of the minimum sample volume of approximately 20 mL. Samples are taken of a monthly composite from Idaho Falls and CFA, and weekly from the EFS. Precipitation samples are analyzed for tritium. Storm events in the first quarter of 2005 produced only enough precipitation for a total of five samples – one from CFA and two each from the EFS and Idaho Falls.
Tritium was not detected above the sample’s 3s value in any sample. Low levels of tritium exist in the environment at all times as a result of cosmic ray reactions with water molecules in the upper atmosphere. Tritium measured in first quarter ESER samples were within the range of values measured elsewhere. The EPA’s ERAMS program collects precipitation samples from across the United States. From 1978 to 2001 tritium measured in those samples ranged from -2.00 to 7.38 x 106 pCi/L (-7.4 to 2.7 x 104 Bq/L) (EPA 2003). Data for all first quarter 2005 precipitation samples collected by the ESER Program are listed in Table C-6 (Appendix C).