Monday, July 30, 2007 - 8:00 AM
S13
The Role of In Situ Bioremediation in Chlorinated Solvent Site Management
Hans Stroo, HGL, Inc., 300 Skycrest Dr., Ashland, OR 97520
Where does in situ bioremediation (ISB) fit in the management of chlorinated solvent sites? The short answer is that it will be used most of the time, over most of the area, at most sites. Although other technologies may be used for plume containment or source depletion, virtually all sites will rely on monitored natural attenuation (MNA) for a significant time, and natural attenuation is primarily (but not solely) a result of biological activities. Engineered ISB can also be used for either source or plume treatment, and its performance has been equivalent to most other competing technologies, at lower cost. However, it is also slower than many other technologies. Finally, ISB can often be used in conjunction with other technologies, so it is likely that ISB will be part of the overall remedy at the majority of CAH sites.
The number of technology options for chlorinated solvents has increased significantly over the last 20 years. Initially, pump and treat was the de facto presumptive remedy. However, the limitations of this approach have stimulated the development of several technologies to treat contaminants in place. As the experience with ISB, and other in situ technologies, has increased, we have gained a better understanding of which approaches are most suited to specific site conditions. Although no simple guidance is possible, we can identify the critical factors influencing the selection process, and the relative strengths and limitations of different remedial technologies.