1 OVERCOMING THE LIMITATIONS OF IN SITU BIOREMEDIATION IN LOW PERMEABILITY SOILS THROUGH HYDRAULIC SOIL FRACTURING

Hydraulic Soil Fracturing is a process that is used to enhance the in situ remediation of contaminants present in low permeability soils (i.e. soils with a hydraulic conductivity of less than 10-6 m/s). Soil fracturing has been successfully applied since the early 1990’s to accelerate site clean-ups using physical “mass transfer ” remediation technologies such as soil vapour extraction and pump and treat. The current trend in in situ remediation is moving away from physical mass transfer processes towards the use of bioremediation to remediate soil and groundwater contamination in situ. Motivating factors for the increasing use of in situ bioremediation include its non-intrusiveness, cost-effectiveness, and speedy conversion of contaminants to innocuous end products. The growing use of in situ bioremediation has also led to the realization that its effectiveness is severely limited in low permeability soils because of constraints for adequate delivery of electron acceptors, nutrients, etc. required for sustained microbial metabolism. Recent applications of bioremediation have demonstrated how soil hydraulic fracturin