The U.S. Navy is preparing to build a treatment system to filter harmful pollutants out of groundwater flowing south from the former Grumman naval weapons plant property in Calverton.

Construction could start as soon as next June, with the system operating as early as next fall, officials said.

During a Navy public hearing at the Jamesport Community Center last Thursday night, federal officials and consultants presented a plan to install two pumps just south of the chain-link fence that runs along River Road in Calverton, where some of the highest concentrations of volatile organic compounds have been found.

About 100 gallons of water per minute will flow through the pumps, said Lora Fly of the Navy, with an air stripper unit used to extract the VOCs — which can harm humans and wildlife — and return the water to state drinking water standards of 5 micrograms per liter. The Navy set for itself a December 2012 deadline for getting the so-called pump-and-treat system up and running.

Meanwhile, Ms. Fly said, “The Navy will continue to evaluate groundwater quality south of the fence line” as the construction of the system moves forward.

VOC concentrations as high as 1,090 micrograms per liter have been found in test wells along the fence that separates the Grumman property from River Road. VOCs have also been detected at high levels in wells farther south of River Road, at the Peconic Sportsman’s Club. And trace amounts have been found in the Peconic River, as the News-Review first reported in 2009.

That report came on the heels of a county groundwater investigation that found VOC levels to be much higher than the Navy had been asserting. At that time, the Navy appeared to be moving forward with plans to do nothing beyond the security fence surrounding the former Grumman complex, now known as the Enterprise Park at Calverton.

A push from county, state and federal lawmakers soon followed.

“We can see the light at the end of the tunnel now,” said Bill Gunther, who chairs the community component of the Navy’s Restoration Advisory Board, which also comprises state, county and federal officials. “The public comment goes until Dec. 21, after which [the Navy] will write up a response summary and record their decisions and explain how they addressed the comments.

Then they go out to bid, get a contract and they’re hoping to start next June. It’s something we’ve been working hard for a long time and we’re almost there.”

As for the public comments, Mr. Gunther, an RAB committee member since 1999, said some had expressed concerns that the current plan includes no designs for treating groundwater south of River Road. But Navy officials explained that access to the county-owned land south of EPCAL has been slow in coming, and that constructing anything in the sensitive wetlands area now, without taking more time to examine the land and groundwater there, could wind up damaging the ecosystem.

Mr. Gunther said the Navy made some good points about how a treatment system could possibly do more harm than good south of the fence.

Treating the area now wasn’t “something we felt so strong about, that it could be done,” he said. “Yes, it is highly dense and you could do some damage, so we did back off on that.”

Navy officials recently gained access to the woods in that area, just west of Connecticut Avenue.

Bill Toedter of the Mattituck-based North Fork Environmental Council said at the meeting that his group worries about whether the Navy will stick to its timeline for building the pump-and-treat system.

“Despite the expressed desire to move forward at an ‘accelerated pace,’ history has shown that efforts at Calverton have continually fallen behind schedule,” Mr. Toedter wrote in a letter to Senator Charles Schumer’s office. “There needs to be a push from the county, state and federal governments to make sure that” the Navy starts pumping by its December 2012 deadline.

Taking a different tack from Mr. Gunther and the rest of the community members on the RAB committee, Mr. Toedter also wrote that the Navy should bring “more resources … to developing a plan for active remediation of the southern half of the plume, including better protection of the Peconic River starting as soon as possible.”

The Calverton plume stretches more than a third of a mile along River Road and to the south and north of the two-lane highway.

The VOCs are believed to be chemical by-products of industrial solvents used by Grumman workers to clean naval aircraft beginning in the 1950s.

No residential wells are located near the heart of the plume, although county health officials have speculated that, depending on how deep the chemicals run, they could be flowing underneath the river and toward the Northampton residential community.

At the request of North Fork Environmental Council members and others in attendance last week, the Navy is working on plans with the state Department of Environmental Conservation to hold one more hearing before adopting the plan.

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