Navy plans treatment plant at Calverton

In a cleanup milestone at the former Grumman defense plant in Calverton, the Navy has proposed building a treatment plant to stanch the flow of polluted groundwater threatening the Peconic River.

The underground plume of industrial solvents is the last big piece of contamination to be addressed at the Navy-owned property, where Grumman assembled and tested aircraft from 1954 to 1996. All but 209 of the site's roughly 3,000 acres have since been handed over to the Town of Riverhead for economic redevelopment.

The Navy agreed to clean up the polluted groundwater last year, after Suffolk County health department tests showed the contamination was far more concentrated and widespread than previously thought.

"They've finally accepted the fact that we need to do an active remediation and not wait for 30 to 40 years, just letting Mother Nature take care of it over time," said Wading River resident Bill Gunther, a longtime member of the citizens advisory board on the cleanup.

More than a mile long, the plume contains solvents and fuel dumped decades earlier at a spot north of River Road where Grumman tested jet aircraft systems for the Navy. Over time, the contaminants moved southeast through groundwater, past Connecticut Avenue and into the river.

The $2.23 million treatment plant would pump up polluted groundwater near the fence line of the property to prevent contamination from spreading further off-site. The Navy would also monitor groundwater there and south of River Road to see if chemical concentrations decline.

"We want to get a better handle on what's here," Navy consultant Dave Brayack of Tetra Tech said at a Jamesport public meeting on the plan this week. "If there's a big problem up here that's moving toward the river, then we're going to have to consider taking more aggressive actions near the river."

The public comment period on the plan runs through Dec. 12. If the state signs off and there are no major objections from the public, construction could begin by spring or summer. Navy officials say the plant could be operating by December 2012.

The Navy has already removed more than 26,000 tons of contaminated soil thought to be the source of the plume.

"They've done a reasonably good job of cleaning up other areas on the site, inside the fence," said Sidney Bail, president of the Wading River Civic Association and a member of the advisory board.

Still, he said: "I don't think any of us anticipated that it would take this long."

For years, the Navy maintained that no treatment was needed and said any lingering groundwater pollution would dissipate on its own over time. But health department tests in 2008 and 2009 revealed that the plume was much more extensive. In some spots, it contained concentrations of chlorinated solvents that were 40 to 200 times higher than state drinking water limits.

No drinking water supplies are directly threatened by the plume, other than a well at the Peconic River Sportsman's Club, which will soon be connected to public water. But the fear is that chlorinated solvents in the plume, along with fuel remnants such as benzene, could harm aquatic life in the river.