Charged Body Potential Monitoring of an Electrolyte Plume Emanating from a Dripping Source

Abstract

Hole-surface charged body potential (CBP) measurements were taken over a 173-day period during a drip-injection, tracer experiment in partially saturated, fractured basalt. A continuous, enhanced conductivity, potassium chloride (KCl) solution was dripped into the fractured basalt and energized directly through a current electrode placed in the conductive solution. The constant concentration, KCl solution was introduced above a perched water table at an average rate of 10.07 L/day under a constant hydraulic head for 76 days. The KCl drip period was followed by a 34-day tap water drip period and a 62-day drainage period. Hole-surface CBP measurements were taken over time to delineate the evolution of the asymmetrical, vadose zone, plume. A 15 by 15 grid of land surface based, porous pot electrodes (copper sulfate), located symmetrically about the centrally located injection borehole, was used for the hole-surface CBP experiment. Ratios of electrical potentials measured at the land surface over time were contoured and profiled to delineate the evolution of the electrolyte plume.

Keywords:

• Charged body potential method
• Fractured basalt
• Vadose zone
• Electrical potentials
• Electrical conductivity
• Plume
• Voltage ratios

Acknowledgments

This investigation was conducted with generous financial support from Lockheed Martin Idaho Technologies, Inc., grant number C95175698-017 and Bechtel BWXT Idaho, LLC, grant number C95175698-017-001. Their support and counsel are greatly appreciated. Technical advice on the experimental design from Kenneth F. Sprenke and Richard (Dutch) Van Blaricom also is greatly appreciated.