BRUNSWICK, Ga. -- Hercules Inc. has resumed work at its outfall canal and adjacent waterways to remove an estimated 25,000 cubic yards of sediment contaminated with toxaphene.
The U.S. Environmental Protection Agency made the canal and two adjacent creeks a Superfund site in 1997 after tests found unacceptable levels of the banned pesticide toxaphene in sediment. Hercules manufactured toxaphene at the plant from 1948 to 1980.
The work that began last week is similar to the work that Hercules undertook more than a year ago when contractors removed 5,000 cubic yards of sediment, said Wayne Quinn, who is overseeing the work for Hercules.
Crews will excavate the canal an additional 3 to 7 feet up to a weir near the canal's mouth, Mr. Quinn said.
Downstream in the canal, workers will excavate up to five feet of sediment along with smaller deposits at six sites along Terry and Dupree creeks, the tidal waterway into which the canal drains, Mr. Quinn said.
"The bulk of the removal is going to be in here," Mr. Quinn said of the downstream portions of the canal.
All the sediment will be placed in lined drying beds and removed once most of the water drains and evaporates from it. The EPA has said toxaphene adheres to sediments and will not escape with the filtered runoff.
In the canal itself, the weir prevents sediments from escaping downstream during the current work but contractors will build another structure across the mouth of the canal for the later work, Mr. Quinn said.
The containment structure will consist of loosely fitted sheet piling lined with a fabric curtain that will allow water to flow while filtering out sediments, he said.
To make sure that no sediments get through, GeoSyntec Consultants is collecting and testing water downstream during the excavations, said Brad Hammar, a member of a U.S. Coast Guard strike force assigned to the site.
GeoSyntec tests the water at several depths and collects water samples every 20 minutes during the test periods, Mr. Hammar said.
Mr. Quinn said the work should be finished in 13 weeks.
The EPA and other agencies are recommending that no one fish or swim in the streams while the toxaphene removal is under way.