What are “background” and “SALs”?
“Background” is the concentration of each radionuclide or other contaminant that would be expected to be in the environment in the absence of LANL. Background concentrations in stream bed sediments are based on extensive sampling of many rivers and streams in northern New Mexico that are distant from LANL. Screening Action Levels (SAL) are also applicable to the sediment portion alone. These levels were proposed by the LANL Environmental Restoration Project to determine when constituents are present at concentrations or activities at a level of concern and would indicate a need for additional samples to clarify. The SALs are set at levels less than what would be considered a human health risk.
