GeoSierra has pioneered the installation of trenchless subsurface permeable reactive barriers (PRBs) for groundwater remediation and has installed kilometers of PRBs at sites throughout the USA. The same technology is used to create a subsurface impermeable barrier, as a freeze wall, or impermeable by grout injection or the injection of a special swellable proppant. The imperable barrier can provide containment of hazardous wastes or as a fluid loss barrier for thermal enhanced oil recovery (EOR) using steam, such as in SAGD (Stream Assisted Gravity Drainage) operations.
Permeable Reactive Barriers - continuous subsurface permeable reactive barriers for groundwater remediation and treatment. Common active agent is zero valent iron filings injected as a propped permeable wall. The wall is constructed by conventional boreholes, drilled along the wall alignment - see Permeable Reactive Barriers.
Subsurface Containment Barriers - continuous subsurface impermeable reactive barriers for waste containment or as fluid flow barrier. The subsurface containment barrier is constructed the same as a subsurface PRB, expect with the injected proppant being either a high permeable 1220 sand or special swellable proppant. The barrier is made impermeable either by 1) cold saline water is re-circulated within the permeable wall to freeze the surrounding formation pore water, creating a substantial impermeable barrier, 2) chemical grout is injected into the permeale wall to render impermeable upon the grout setting, or 3) a special swellable proppant injected in the installation of the wall, swells over bays to yield a continuous imperable barrier - SubSurface Barriers.
Soil Remediation - horizontal permeable inclusions are constructed by injecting into an overconsolidated clay for either, 1) enhanced Soil Vapor Extraction (SVE) for the removal of organics from the clay, or 2) as iron filled permeable inclusions for a re-circulating groundwater treatment system to clean the clay in situ. Alternatively an environmental version of the ERG system can be installed in weakly cemented formations and by electric resistive heating can in situ heat contaminants to elavated temperature exceeding 300°C, much greater than 3 or 6 phase electrical heating of which both are limited to the temperature of the water boiling point and have other limitations relating to the formation's electrical properties - see Soil Remediation.