Automated Leak Detection on Underground Storage Tanks Using Geophysical Methods at the Hanford Nuclear Site

Oral Presentation

Prepared by S. Calendine, D. Rucker, M. Levitt, N. Crook
hydroGEOPHYSCS, Inc., 2302 N. Forbes Blvd, Tucson, AZ, 85745, United States


Contact Information: Scalendine@hgiworld.com; 520-647-3315


ABSTRACT

At the Hanford Nuclear Site in Washington State, the Department of Energy oversees the containment, treatment, and retrieval of high-level mixed radioactive waste. Much of the waste is currently stored in single-shelled tanks (SSTs) that are well beyond their design life. Currently, the waste is being retrieved from the SSTs and transferred into new double-shelled tanks (DSTs) for temporary storage before final treatment. Monitoring the tanks during the retrieval processes is critical in ensuring tank integrity and creating an early warning system for potential leaks in the older SSTís.

An electrical geophysics monitoring program for Leak Detection and Monitoring (LDM) has been successfully deployed on SSTs at the Hanford site since May of 2004. The monitoring program takes advantage of changes in electrical properties that will occur when conductive tank liquid leaks into soil contiguous to the subsurface tank shell. During monitoring, voltages are measured and recorded on steel cased wells, surface electrodes, and the tanks themselves. Data acquisition hardware and software allow for continuous real-time monitoring of the received voltages through time-series data analysis, creating a highly sensitive method of leak detection and complementing drywell geophysical logging as a means to detect and quantify leaks. Working in an industrial environment such as the Hanford site involves many challenges for electrical monitoring, such as cathodic protection, grounded electrical infrastructure, lightning strikes, diurnal and seasonal temperature trends, and precipitation, to create a complex environment for leak detection analysis. In this discussion, we present solutions to the complicated challenges of working in the tank farms of the Hanford site.