Posted on September 19, 2016
By James M. O'Neill, NorthJersey.com
Water that had been squeezed out of contaminated sediment, treated and then pumped back into a section of Pompton Lake this month still ended up with levels of pollution that were higher than the state allows, adding another hurdle to a long-delayed cleanup project that began two weeks ago.
The water had elevated levels of mercury, copper and organic carbon.
The Environmental Protection Agency, which is overseeing the cleanup, said there is nothing to indicate the polluted water poses any threat to human health, EPA spokesman David Kluesner said Wednesday.
Chemours, the company responsible for cleaning up the lake’s contaminated sediment, is trying to figure out how to better treat the water. The company has brought in an extra storage tank to hold water from dredged sediment until it can improve treatment and start pumping the water into the lake again.
With the extra tank in place, dredging the contaminated sediment can continue without disruption, Kluesner said.
The three-year, nearly $50 million dredging operation will ultimately remove 130,000 cubic yards of contaminated sediment from the lake bottom. The contamination comes from the former DuPont munitions facility in Pompton Lakes and Wanaque. The pollution was carried to the lake from Acid Brook, which flows through the old DuPont site. The facility operated from 1902 to 1994, making blasting caps, metal wires and aluminum and copper ammunition shells for the U.S. military.
The EPA wants the sediment removed because a toxic form of mercury can build up in fish, posing a health risk to people who eat them. Exposure to mercury can damage human nervous system and harm the brain, kidneys, heart, lungs and immune system.
The dredging began Aug 31 after years of studies, reports, delays and conflicts involving the EPA, residents and DuPont.
The 200-acre Pompton Lake, bordered by Pompton Lakes, Wayne and Oakland, is a backup source to replenish a key reservoir that supplies drinking water to towns in Bergen and Passaic counties.
About 3,742 gallons of contaminated water had been pumped back into the lake over a 55-minute period on Sept. 6, and sample test results from a lab indicated the elevated levels of contamination. As a result, no more water was pumped into the lake.
The water contained 11.8 parts per billion of mercury, exceeding the state permit limit of 1 part per billion, according to a letter sent to the state Department of Environmental Protection by Sevenson Environmental Services Inc., Chemours’ contractor handling the dredging. Copper levels were at 102.7 parts per billion, compared with the permit maximum of 100, and organic carbon was at 29.2 parts per million, while the permit allows a maximum of 20 parts per million.
“No additional discharges have been conducted after failing results were received,” wrote W. Mark Schmitt, Sevenson’s project manager, in his letter to the EPA this week.
“Chemours is looking at what additional chemical or physical treatment is needed so future water discharges don’t exceed permit limits,” Kluesner said.
Stevenson is looking to place existing water treatment tanks in a series so more solids can settle out of the water. It plans to place existing bag filters in a series with finer filter cloths to trap more solids. It is installing a new filter downstream of the treatment equipment to capture any remaining suspended solids. And it is evaluating whether to use additives to the temporary tank to remove dissolved metals, Schmitt wrote.
“The discharge of water associated with sediment removal is not expected to pose a risk to human health or the environment,” Schmitt wrote to the DEP, which issued the permit to discharge the water.