Syracuse -- A month after it halted its dredging of polluted muck from Onondaga Lake for the winter, Honeywell International has restarted an operation to extract even more dangerous concentrations of chemicals along its shore.

On Dec. 20 the company flipped the switch on an expanded effort to trap and remove a potent brew of pollutants in the soil.

The chemicals are too toxic to be sent to a containment area in Camillus, which is where the sediments being dredged from the lake are going. Instead, the chemicals are sucked into a truck and driven to a hazardous waste facility in Baltimore.

The pollution is so extensive it will take decades to trap and remove all of it, said Ken Lynch, regional director of the state Department of Environmental Conservation.

The toxic mix — mostly chlorinated benzenes — is the legacy of years of spills from an Allied Chemical factory on Willis Avenue that closed in 1977. The plant manufactured dichlorobenzenes for use in a variety of products, from mothballs to the deodorant cakes used in urinals.

The chemicals are denser than water and do not easily dissolve. For decades, they have been seeping underground, below the groundwater, and flowing slowly to the lake.

Honeywell has been trapping the chemicals in collection wells along the southwestern shore since 1995. So far 44,000 gallons have been trucked out. But that’s a fraction of the tens of thousands of gallons the DEC said remain underground.

Three years ago, Honeywell built a nearly 11/2-mile submerged steel barrier along the shoreline — 70 feet deep in some places — to block any more of the chemicals from entering the lake. The barrier was extended into a portion of the lake containing the highest concentrations of the chemicals.

About two acres of lake were enclosed by the wall and filled in with soil, becoming an extension of the shoreline. During the past year, Honeywell shut off the pumps in its collection wells so it could install more wells there.

There are 31 such wells along the southwestern shore. The wells — essentially pipes driven dozens of feet into the ground — have porous screens along the sides to allow the heavy chemicals to flow into them. Each well has a pump that pushes the chemicals up to a holding tank onshore.

The Allied Chemical plant, which sat along the shoreline of Onondaga Lake, is responsible for much of the pollution that's currently being pulled out of the water and shoreline.

Every 60 to 90 days, a truck sucks about 500 gallons out of the tank for transport to the Clean Harbors hazardous waste facility in Baltimore.

The system is a scaled-back — and less expensive — version of the original plan in the “record of decision” signed in 2005 by Honeywell, the DEC and the federal Environmental Protection Agency. That plan called for the barrier wall to hug the shoreline without entering the lake. The most highly contaminated sediment in the lake would have been dug up and trucked to a hazardous waste facility.

But subsequent testing found that the most contaminated areas did not extend into the lake as far as was thought, Lynch said. In 2006, the DEC and EPA agreed that Honeywell could extend the barrier wall into the lake to contain the most hazardous areas. The new design also moved the operation away from Interstate 690, eliminating any possibility that the digging could destabilize the highway.

With the most contaminated sediment trapped within the barrier wall, the less polluted muck remaining in the lake was considered safe enough to be dredged and piped to the containment area in Camillus.

The new plan reduced the entire amount of dredging to be done in the lake from 2.65 million cubic yards to about 2 million. It also greatly reduced the number of truckloads of material that would have to be sent to a hazardous waste facility.

The DEC says there are still small “beads” of the dense chemicals in the lake. Dichlorobenzenes are federally listed hazardous wastes, but they are in small concentrations in the sediment pumped to the Camillus site, Lynch said.

“If you just grabbed one sample in the sediment, it could test at levels that would classify as a hazardous waste,” he said. “But when you dredge it and you mix it with a slurry and other material that are not hazardous, it’s likely that it won’t be hazardous waste at that point.”

Even if the waste was considered hazardous, he said, the DEC is legally allowed to send it to Camillus — which is not a licensed hazardous waste facility.

“In this case the law allows you to treat or dispose of hazardous waste for a specific remedial site as long as it’s done consistent with state — and in this case, federal — law for treating and handling hazardous waste,” he said.

The sediments that are piped to Camillus are not tested as they come out of the lake. Lynch said the DEC and the EPA are relying on the extensive sampling and testing done over the years by both Honeywell and the DEC to map the lake’s pollutants.

The continuous air sampling at the Camillus containment site is an extra assurance that residents near the facility are not being exposed to health risks, Lynch said.

Sam Sage, president of the Atlantic States Legal Foundation, the Syracuse group that sued in the 1980s to force Onondaga County to stop polluting the lake, is not a fan of the current dredging plan. But he said he has seen nothing to suggest the material being piped to Camillus is a health hazard.

“It isn’t something I would use as toothpaste, but it’s not exactly going to kill you,” he said.

Contact Paul Riede at priede@syracuse.com or 470-3260.