The following is a press release from the Pine River Superfund Citizen Task Force.
Over 115,000 pounds of a toxic contaminant have been recovered so far by EPA at the Velsicol Superfund Site in St. Louis, Michigan.
Prior modeling had predicted that the amount to be removed would fill about four tanker trucks. Instead, twelve tankers have already been filled, with no end in sight.
The contaminant being removed is DNAPL (dense non-aqueous phase liquid). EPA Project Manager Tom Alcamo said this is a very heavy DNAPL. “Water weighs 8 pounds per gallon, and this DNAPL weighs 17 pounds per gallon.”
To liquefy the DNAPL so that it can be pumped from 30 feet underground, thousands of kilowatts of electricity are applied through heating elements that extend in almost 300 wells. Once the temperature underground reaches 100 C (boiling), it is held there for at least 90 days. The present cleanup area is about one and a half acres of the 52-acre former chemical plant site.
The EPA’s contract with Cascade, the thermal destruction company, called for the underground heating to cease on July 7. Alcamo said there has been no reduction in the amount of waste coming up, so heating will continue until they see “diminishing returns.” He added that he has enough money in the budget to continue the process until it is finished. The operation is costing about $1 million a month.
The DNAPL is comprised of various chemicals, including a male sterilant DBCP (1,2-Dibromo-3-chloropropane). Alcamo said two “hits” of DBCP occurred in the air at the site in June, and added, “The lesson we learned is to open the weir tanks carefully.” When the DNAPL is drawn up through the wells, it is accompanied by groundwater. Both liquids are pumped into weir tanks where the DNAPL settles to the bottom. Once it has separated out, the DNAPL is then pumped into the tanker trucks.
The trucks transport the waste to EPA-certified incinerators in El Dorado, Arkansas.