Using Enhanced Natural Bioremediation to Reduce Costs and Accelerate Closure

 

In November of 1995 Envirologic Technologies, Inc., became the first company in the country to implement a source area treatment using Oxygen Release Compound (ORC^Ò) from Regenesis. Since the inception of this project, the use of enhanced natural attenuation as a remedial technology has expanded dramatically. ORC^Ò enhanced natural attenuation is currently being utilized throughout the country. In addition, this method is beginning to gain international popularity, with ORC^Ò currently in use in nine countries. When applied properly ORC^Ò enhanced natural attenuation can be a very cost effective remedial alternative.

Since the initial application of ORC^Ò, Envirologic has utilized enhanced natural attenuation at eight additional sites. The remedial objective at these sites has been to reduce on-site contaminant concentrations to levels low enough to prevent off-site groundwater impact. Under Michigan's Risk Based Corrective Action (RBCA) process to these sites, could then be closed using land use restrictions appropriate for the site. Costs to complete the ORC^Ò installations have ranged from $12,000 to $25,000 depending on the magnitude of the release and other factors such as groundwater flow velocity, amount of naturally occurring oxygen present and depth to groundwater, to name a few.

As a result of these efforts, contaminant concentrations have shown a marked decrease at all of the facilities. Many of the sites showed significant contaminant reduction within ninety days of ORC^Ò installation. The results after 90 days at three sites, with very different contaminant concentrations, are compared in the figure located above right. The results demonstrate that the enhanced natural attenuation is quickly reducing source area concentrations. By reducing the source area concentrations, the downgradient edges of these plumes have begun to recede, thus accomplishing the objective of risk reduction under the RBCA process. Three of the eight sites are expected to reach closure within the next year, without additional treatment. These results are being achieved at a fraction of the cost typically associated with active treatment systems.

bohan@envirologic.com