The GeoSierra PRB installation method—also known as azimuth oriented vertical hydraulic fracturing and vertical inclusion propagation (VIP)—is an alternate mode of constructing iron PRBs in situ, resulting in significant cost savings and allowing reactive barriers to be installed to greater depths than conventional technologies. We have used this technology to install iron PRBs at numerous sites, with geologies ranging from silts to clays, glacial tills to highly permeable sands and gravels with depths ranging from 15 feet to greater than 120 feet.
GeoSierra PRBs are constructed from a series of wells installed along the barrier's azimuth or bearing. Each well is installed using conventional drilling methods and comprised of a specialized casing grouted into the boreholes. A controlled vertical inclusion is initiated in each well at the required azimuth orientation and depth. Iron filings are injected into the wells in a highly viscous cross linked proprietary gel that forms the continuous permeable iron reactive barrier. The barrier's geometry can be monitored in real time to ensure the barrier is constructed as designed.
When compared to oil and gas hydraulic fracturing techniques that may destroy formation permeability through exceptionally high injection flows and pressures, use of the GeoSierra technology preserves formation permeability by mechanically placing the PRB through low flow and low pressure injection techniques. Additionally, while large scale energy fracturing programs utilize numerous additives, our gel combination is comprised of food-grade ingredients.
The GeoSierra method allows us to remediate groundwater plumes that in most cases, because of their depth, would otherwise be impossible to reach. It’s a flexible technology, however, and is often also the best choice for PRBs at depths less than 40 feet.