Tank Leak Detection Using Electrical Resistance Methods

Two field experiments were performed to evaluate the performance of electrical<br>resistance tomography (ERT) as a leak detection method under metal underground<br>storage tanks (UST). This paper provides a summary of the field experiments performed<br>under a 15 m diameter steel tank mockup located at the Hanford Reservation,<br>Washington. Two different leak events were created. About 3800 liters of saline solution<br>were first released along a portion of the tank’s edge and another 1900 liters were later<br>released near the tank’s center. The release rate averaged about 26 liters/hour for the leak<br>on the tank’s side and about 3.0 liters/hour for the center leak. Two and three<br>dimensional tomographs were calculated using data collected before, during and after<br>each spill. The tomographs show that, as the solution penetrated the soil, readily<br>detectable resistivity decreases appeared where the associated plume was expected. The<br>results indicate that the plume associated with these releases could be reliably detected<br>after approximately 190 liters were released. Results are also shown where the metal<br>tank is used as a large electrode.