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.