Northrop Grumman Corp. and a subsidiary want a lawsuit filed by Bethpage Water District over groundwater contamination to be thrown out of court in part because the claims are "speculative and remote."

In documents filed Tuesday evening in U.S. District Court in Central Islip, the defense contractor also said a statute of limitations on claims has passed and asked the judge to dismiss the water district's complaint.

Northrop Grumman's attorney Mark A. Chertok referred questions to the defense contractor's spokeswoman, Christine Restani, who declined to comment because the matter is in litigation.

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"Grumman's answer is not surprising and we will continue to prosecute our claims on behalf of the district in this litigation," said attorney Curt D. Marshall, who represents the Bethpage Water District.

The filing is the latest in a tussle over groundwater plumes that have long plagued water quality in Bethpage and now threaten other drinking water suppliers.

Starting in 1942, the Navy and what is now Northrop Grumman operated research, testing, design, fabrication and assembly plants on a more than 600-acre facility in Bethpage. Groundwater contamination was first documented in the late 1940s, and the sites were added to the state Superfund registry in 1983.

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Manufacturing ended in 1998, but two groundwater plumes have been traced back to operations that included the development of the Apollo Lunar Module.

In late 2013, Bethpage Water District filed suit against Northrop Grumman and Northrop Grumman Systems Corp. seeking damages to cover the costs of groundwater treatment already expended and those that may be incurred in the future.

The district amended the complaint in March to include details about high levels of the carcinogenic solvent trichloroethylene that in 2014 was found 2,100 feet from a Bethpage well. The levels were as high as 4,600 parts per billion. The drinking water standard is 5 parts per billion.

Northrop Grumman's response denied a Bethpage claim that the new contamination indicated on-site containment was failing or that a second plume was coming from the property.

Northrop Grumman also said another hot spot of contamination emanating from a groundwater plume at Bethpage Community Park may never reach water district wells.

Bethpage officials have drilled a new well outside the plume boundaries to avoid contamination. In the past they said they need to be prepared before contamination hits wells so as to protect customers.

"They don't have the opportunity to roll the dice," said Rich Humann, president and chief executive of H2M Architects + Engineers, an engineering firm that represents Bethpage and other water suppliers. "They need to anticipate that the worst concentrations could hit and be prepared."