Orion teamed with IESI of Braintree, Massachusetts, to design and implement an enhanced anaerobic dechlorination (EAD) system to provide in-situ biological treatment of approximately 4 million gallons of groundwater at a former manufacturing facility in Southern California.
The EAD system consists of a network of extraction and injection wells that recirculate approximately 1 million gallons of groundwater in the targeted treatment area every month. Orion staff perform weekly injections of a blend of ethanol, methanol, and n-propyl alcohol to create an anerobic environment in groundwater. This promotes the growth of bacteria such as dehalococcoides (DHE) that naturally consume and break down chlorinated solvents in groundwater. DHE is important to cultivate because it is a species of bacteria capable of completely reducing PCE or TCE to harmless byproducts such as ethene. Other bacteria species can only reduce PCE or TCE to contaminant daughter products including dichloroethylenes or vinyl chloride. The well network recirculates the chemical blend along with groundwater throughout the target treatment area. Orion staff take weekly system readings, weekly water quality measurements, and monthly groundwater samples to ensure compliance with regulatory permits and evaluate system performance against optimal conditions.
Orion employs advanced analytical methods for monitoring performance. The groundwater treatment system tracks recirculation flow rates continuously and automatically emails Orion and IESI daily. This creates a detailed record of system performance and allows for frequent and precise optimization throughout the week. In addition, Orion uses quantitative polymerase chain reaction (qPCR) to monitor the growth of DHE in the treatment area. qPCR detects the number of copies of specific genes in a sample and aids in system optimization by providing information about microorganism activity. This information, combined with water quality readings, aids Orion in optimizing chemical additions to maximize DHE growth rate.
Results of recent performance monitoring samples indicate that the system is effective based on increases in VOC degradation byproducts, VOC desorption, and microbial populations and activity. Orion expects EAD operation to reduce VOC contaminant levels over 90% to less than 100 micrograms per liter on average in the treatment area over 2 years.
Conveyance Piping and Chemical Hoses
Aerial View of Treatment Compound
Extraction and Injection Well Manifold