GeoSierra’s patented active resistivity method of providing real-time images of injected fluid geometry during PRB construction was conceived and developed over a number of years. This imaging technology allows the installation of the reactive barrier wall to be displayed in real-time, and thus determine its geometrical extent and ensure the wall is coalesced between injection wells. The gel iron mixture is energized by a 100Hz low voltage source. Down-hole resistivity receivers are monitored to detect changes in induced voltages by the propagation of the injected fluid. From these induced voltages, injected fluid flow rates and utilizing an incremental inverse integral method, the injected geometry is displayed in real time during the installation process.

The first commercial application of the technology was for the installation of the iron PRB at the Caldwell Superfund Site in Fairfield, NJ in 1997. Since then GeoSierra’s real-time imaging technology has been used at all of GeoSierra’s PRB installations to ensure each PRB is constructed as planned according to quality assurance specification requirements. Also the technology has been used to image the geometrical extent of injected fluids into the subsurface for other remedial applications.

Active Resistivity Imaging