Peconic River Cleanup Begins
Excavation of contaminated Peconic River sediments began in on-site portions of the river in April 2004. The work involved the removal, treatment, and disposal of river sediments extending from BNL's Sewage Treatment Plant to the site boundary and into Suffolk County Parkland.
Six to 12 inches of sediment were removed from areas where contaminants were deposited and from areas identified as preferential sources of methylmercury, the form of organic mercury found in the environment that accumulated in fish and human tissue. It was estimated that removal of the sediment would remove 95 percent of the mercury and many of the other contaminants.
The cleanup of the areas off-site began in late fall after securing an access agreement from the Suffolk County Legislature. This portion of the cleanup was completed in the spring of 2005.
Following the sediment removal, the river banks were regraded and vegetation was restored with native river plants. The cleanup was completed in July 2005. In all, some 21,000 cubic yards of contaiminated sediment was removed from 4.66 miles of the river, an area that totaled 19.8 acres, was cleaned up.
After several years of monitoring, with exceptions at two sampling locations, one on-site and one off, contaminants in the water column, sediment, and in the fish, are trending downward.
In 2010/2011, BNL went back into the river to cleanup the two areas (approximately a third of an acre) where sampling showed some residual mercury contamination at levels above the cleanup goals. The sediment trap, which had been constructed in 2002 to minimize the potential migration of contaminants off the BNL property, was also removed.