AWWA ACE69002

This powerpoint presentation begins by presenting a brief overview of radionuclides and how they are formed. The Colorado Radionuclide Abatement and Disposal Strategy is presented, along with the Radionuclide Sample Variability Investigation. The project approach included a literature review, laboratory standard operating procedures (SOPs) Review and Survey, and a confirmation sampling program. Lessons learned from sampling include the following: lab selection could impact compliance; same sample analyzed by various laboratories produced a wide variety of results for GAA and radium; variability could be attributed to a wide variety of issues; for example, sample volumes analyzed, sample preparation methods, calibration standard selection, and count times; conversion of uranium from mass to activity can have significant compliance implications; for example, using the conservative 0.67 pCi/ug mass to activity ratio can result in non-compliance with adjusted GAA. Big picture recommendations include the following: use U.S. Environmental Protection Agency's (USEPA's) GAA Method 900.0 for screening purposes; for example, if GAA > ~5 and <~30 pCi/L: require system to conduct additional sampling using USEPA Method 00-02 (co-precipitation), which is believed by some industry experts to be more accurate and precise; further evaluate GAA variability using EPA Method 00-02; further investigate radium variability; for systems that have potential adjusted GAA compliance issues and confirmed uranium present: identify source-specific mass-to-activity ratio; measure U-238 to U-234 isotopically and determine conversion or measure uranium activity directly. Impacts to Colorado Department of Public Health and Environment (CDPHE): direct benefits to CO-RADS; consistent sampling and analysis protocols were used to ensure better quality data; understanding variability provided insight during data evaluation; indirect benefits to Laboratory Certification Program; greater awareness of issue and potential magnitude; increased scrutiny of certified labs; and, issues will need additional investigation before long term improvements will be made. Includes tables, figures.