Soil Remediation

Frac Enhanced Soil Vapor Extraction: GeoSierra has pioneered the use of inclusion propagation using non-invasive fluids to enhance the permeability of low permeable soils for effective Soil Vapor Extraction (SVE). Tight soils are not amenable to conventional SVE due to their low permeability. Installing horizontal sand filled inclusions into these soils significantly increases the soil mass permeability and greatly enhances the radius of influence of the SVE extraction wells. Fracture enhanced SVE significnatly reduces the cost and time to remediate tight soil formations.

GeoSierra has completed numerous fracture enhanced SVE projects at sites throughout North America. Many of the projects are operating chemical or manufacturing facilities requiring horizontal fractures to be installed beneath and around existing buildings and utilities. The buildings are monitored by a high precision bi-axial tilt meter and the fracture geometry is recorded during injection by the active resistivity method.

The fracture enhanced SVE system typically consists of a high vacuum, high flow system to maximize removal of contaminants. The high vacuum stress in the fractures induces rapid removal of the contaminants from the soil matrix and then flow into the nearby fractures for removal. Such a system typically results in planned levels of soil remediation within 1-2 years. To download project description of Enhanced SVE see Enhanced SVE and for a dual phase system installtion see Enhanced Dual Phase SVE and Enhanced SVE Paper.

Tight low permeable soils are not amenable to conventional in situ remediation due to their low permeability. Installing horizontal permeable fractures in the soil by hydraulic fracturing greater enhances the soil mass permeability and access to the contaminants. For chlorinated solvent contamination, GeoSierra has pioneered the use of installing iron filings into the subsurface to abiotic dehalogenate the contaminants to non-toxic end products.

An operating dry cleaning facility in Atlanta, GA was contaminated with Tetrachloroethene (PCE) at high concentrations in the groundwater in a low permeable weathered residuum. Horizontal fractures were installed beneath and around the building with iron filled fractures placed near the residuum bedrock contact. During installation of the fractures the building was monitored by high-precision bi-axial tilt meters and the fracture geometry was determined by the active resistivity method.

The in situ treatment cell consists of highly permeable iron filled horizontal fractures with a low volume recirculation pump. The re-circulation of the groundwater through the iron filled fractures provides significant residence time to destroy even extremely high levels of PCE and daughter product contamination. Such high concentrations of contaminants can be degraded reasonably quickly within 6-12 months and areas of source contamination can be remediated within 1-2 years. View a one page summary of In Situ Treatment Cell. Volatile organic compounds and metals treated by zero valent iron:- VOCs & Metals

In Situ Thermal Destruction: GeoSierra's ERG technology for enhanced oil and gas recovery, can be used for the in situ thermal destruction of contaminants in the subsurface. ERG has the benefit of high elevated temperatures of ~300°C compared to three and six phase heating, which are limited to the boiling point of water and the electrical conductivity of the soils. See ERG electric resistive heating Electric EOR for an explanation of the ERG system.

Enhanced In Situ Treatment Cell