Bioremediation was selected as either the treatment or final polishing step for five dry cleaner sites in the Seattle area and has been applied at three sites. PCE concentrations range from very low (100's of ug/l) to DNAPL levels (160,000 ug/l). Daughter products are present at all five sites. Three of the sites are now empty lots but all involve implementation under roads, parking lots and/or buildings. Dual phase extraction is currently being performed at the highest concentration site; bio will follow.
One bio implementation used the injection of micro scale zero-valent-iron (ZVI) to both treat PCE and help generate and maintain anaerobic conditions in the source zone for the microbes. Simply lowering a magnet into monitoring wells was sufficient to confirm the micro scale ZVI distribution (see black particles in 2nd photo below).