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.
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.