After two years of negotiation, Georgia's Environmental Protection Division and Olin Chemical have agreed on a cleanup plan for toxic mercury discovered in a drainage canal that feeds the Savannah River.

The cleanup, costing about $3 million, involves damming the canal's outfall at the river and filling the channel with clean fill dirt -- essentially encapsulating the mercury-laden sludge to prevent its further spread.

According to a proposed consent order drafted by the department and signed by Olin, fill dirt used in the project will be excavated at the Olin plant site in south Richmond County and tested for contamination before it is placed into the drainage channel.

In 2006, elevated levels of mercury were found in the 43-year-old canal in samples taken by a high school student working on a science project. Her findings were later validated by private consultants.

Frank Carl, the director of Savannah Riverkeeper Inc., which has been critical of Olin's continued use of mercury in its chlorine manufacturing processes, said he is disappointed in the cleanup plan.

Environmental groups, he said, preferred that the mercury sludge be excavated and taken to a hazardous waste landfill, rather than simply being buried in place.

He also expressed concern over Olin's plan to reroute the wastewater outfall by extending pipes to empty the effluent directly into the river.

"Our biggest objection is running the outfall straight to the river," he said. "If in 20 years they put that much mercury into the canal channel, now they're going to be putting that much mercury into the river."

Olin officials have said their wastewater is thoroughly tested and the minute amounts of mercury in its discharges are well below the levels outlined in their EPD permit.

Mercury is categorized as a persistent bio-accumulative toxic because it can build up in the tissue of fish or animals that ingest it, and it can cause an array of health problems in humans.

The consent order is out for public comment through June 11 and is available online at www.gaepd.org. Once the order becomes final, work can commence at the site.

Reach Rob Pavey at 868-1222, ext. 119, or rob.pavey@augustachronicle.com.