Enhanced Amendment Delivery to Low Permeability Zones for Chlorinated Solvent Source Area Bioremediation
Final rept. Feb 2009 Oct 2014
GSI ENVIRONMENTAL INC HOUSTON TX
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This project demonstrated the use of shear-thinning fluid based technology to improve treatment within low-permeability low-k zones of heterogeneous subsurface environments. These low-k zones can serve as a long-term secondary source of contamination because transport may be diffusion controlled, yet they are difficult to target using standard injection-based treatment approaches. A shear-thinning fluid can be used to distribute a bioremediation amendment e.g., lactate around an injection well such that the solution was able to better penetrate and deliver the amendments to both high and low-permeability zones. When injected at a relatively high velocity compared to natural groundwater flow velocities, the shear-thinning nature of the solution allows it to flow more readily and cross-flow from high to low-permeability zones is promoted. During the demonstration at Joint Base Lewis-McChord, the shear-thinning fluid improved amendment distribution by approximately 41 with enhanced persistence and treatment effectiveness within the lower-k zones of the heterogeneous aquifer. It is anticipated that permeability contrasts of 1-2 orders of magnitude are amenable to this technology e.g., improving distribution to silt layers within a sand matrix, but not clay layers.
- Solid Wastes and Pollution and Control