Enhanced reductive dechlorination is based on attaining and maintaining control of an aquifer for a period of time sufficient to degrade all constituents of concern and their daughter products. Attaining and maintaining control of an aquifer is highly dependent on the hydrogeology and geochemistry of the site along with the microbial populations present. Since the hydrogeology and geochemistry is different for every site, a blanket cost can not be given for any specific site. In general, enhanced reductive dechlorination will cost less than $10 per cubic yard of media treated on most non-DNAPL sites. This compares with about $60 per cubic yard for excavation (without disposal) and about $90 per cubic yard for chemical oxidation.
Because freight is costed from a warehouse to a delivery point, freight costs are quoted separately. Unless otherwise stated, due to the volatility of the fuels market, freight costs are generally valid for 30 days. Consideration should be given to the receiving facility’s capacity to off load a truck. In situations where the product is delivered to a facility without the capacity to off-load a delivery vehicle, arrangements can be made (for an additional charge) for delivery on a vehicle with a lift gate and pallet jack.
Reinjection schedules should be based on the geochemistry of an aquifer and not on a calendar schedule. In many cases, multiple injections can be spaced further apart over time.
Since the main goal of adding a substrate to an aquifer is to attain and maintain anaerobic conditions for an extended period of time, because of the limited flows clay sites should be ideal for enhanced reductive dechlorination. In practice, clay sites with adequately spaced injection points usually show very rapid response to substrate addition.
Injection spacing should be sufficient to promote robust reductive dechlorination throughout the treatment zone for a time sufficient to attain complete reductive dechlorination. Injection spacing is dependent upon the dissolution rate of the substrate, the dosage, aquifer velocity, and competing electron acceptor and contaminant flux.
