The following article was written by Melora Grattan and published in the recent addition of the Florida Specifier newspaper regarding the CleanInject(TM) technology:
Using activated carbon to remove contaminants from the air and liquids is nothing new. However, turning the process around and injecting an activated carbon-based slurry into the ground for remediation purposes is not exactly commonplace.
A demonstration of the in-situ process applied to cleaning up contamination from leaking underground storage tanks is underway at a pilot project at a petroleum-impacted site in South Carolina.
The former gas station was treated for four days this past August with the CleanInject(TM) system. The effort produced an 86 percent reduction in contamination concentrations three months later, said Brian E. Chew Sr., PG, principal hydroge-ologist with North Carolina-based Enviro-Equipment Inc.
The test involved injecting the area near the tanks and fuel islands as well as downgradient where contaminants had migrated.
“We had leftover carbon and treated the area where it migrated and added 20 more injection spots. It knocked almost all of it out,” said Chew, whose company is mass producing the patent-pending remediation systems for Resource Geoscience. Colorado-based Resource Geoscience is run by Thomas B. Lewis, the company president and lead inventor of the CleanInject system.
In a July 2012 paper analyzing the use of activated carbon to clean up petroleum contamination, Lewis said his firm starting using the process on tank sites in 2006.
“As our own understanding of the steps to properly design and inject carbon-based injectate evolved, we began seeing unparalleled results in sites remediated with CBI. In fact, the success rates were so great that we began questioning how rates like these were even possible,” he wrote.
Lewis went on to say that he conducted a survey and found that only the five states of Colorado, Wyoming, Kentucky, Oregon and Utah said they use the technology. He attributes this partly to injectates having developed a bad reputation from previous failures and regulators not wanting to depart from conventional methods.
Chew believes that Florida has ideal sites for remediation with CBI due to its surplus of contaminated sites along the coast.
Sites on the coastal plains are ideal, he said, because the contaminants are shallow and it is easier to penetrate coastal sediments with a geoprobe than denser materials such as bedrock and clay or silt stone.
The best thing about the technology, said Chew, is its simplicity. It combines the known use of carbon with the trend toward using in-situ technologies.
“It uses a common material that is not dangerous. The bacteria will grow on it and regenerate it,” he said. “Plus, the carbon can be left in place or landfilled because the chemicals won’t leach out of it. It is a basic, easy process. It’s surprising that it hasn’t been done a lot before.”
Chew said the CleanInject system utilizes a double diaphram pump that fracs the carbon into the ground at up to 1400 psi versus 100 to 300 for similar pumps.
The system mixes the carbon and water in the correct proportions then pumps it into a mixing tank that keeps the dust and typical mess from the carbon to a minimum.
The mix, which varies with the type of material and concentrations of contaminants in the ground, is a fine grade containing no additives.
Chew said he expects the SC site to cost between half and three-fourths of the $100,000 bid and be completed in half the time.
The site will be re-sampled in early 2013 to see if more injections are needed.
If the contaminant amounts are below site specific target levels, the job will be finished except for a final round of sampling to confirm diminished contaminant levels. If the contaminants are above site-specific target levels, more injections may be needed.
Other conventional technologies, such as sparge and vent, could take around two years to produce a similar result and cost three to five times more, Chew estimated. “There are hundreds of thousands of these sites out there and new ones popping up every day,” he said.
Other possible uses for the technology include marine sediment remediation, wellhead protection and sensitive receptor protection.
Moreover, the carbon material could be injected beforehand in excavation areas known to contain petroleum contamination as a way to protect workers and minimize transference during excavation work.
If you have any questions about the carbon injection technology mentioned above or if you know of someone in need of petrochemical remediation, please contact us at remediation(at)enviroequipment(dot)com. We welcome comments on our blog so please feel free to share your thoughts below.
Brian E Chew Sr. P.G.