A $450 million plan to redevelop a former explosives manufacturing site in New Jersey into a major natural gas liquids export terminal has Delaware River environmental groups marshaling forces to block the project.

Delaware River Partners LLC, a subsidiary of New York City-based Fortress Investment Group, is seeking permits from the Delaware River Basin Commission and other regulators to create the deepwater port at the former DuPont Repauno Works site near Gibbstown in Greenwich Township, N.J.

Project backers portray the 218-acre Gibbstown Logistics Center as handling automobiles for roll-on, roll-off vessels, non-containerized break bulk cargo, bulk products and liquids delivered by trucks or rail. New dredging on 45 acres of river bottom would connect new berths for two 966’ vessels to the federal channel at the same depth of 43’.

The site already includes a cavern carved by DuPont into granite bedrock that can store up to 7.8 million gals. of butane or propane that Fortress could sell overseas for plastic manufacture – the same market that Sunoco aims for with its Marcus Hook, Pa., refinery on the river.

But the Delaware Riverkeeper environmental group contends sifting through Securities and Exchange Commission filings and other documents hints that a big future market in liquefied natural gas (LNG) exports is on the developers’ minds.

At a June 6 hearing on the application, a Delaware River Basin Commission staffer mentioned that LNG would be another commodity, “yet there is nothing in the (application) document,” Riverkeeper deputy director Tracy Carluccio said in a Tuesday telephone conference with reporters. “They should not vote on this application.”

LNG and natural gas projects are a hot-button issue in densely populated New Jersey and eastern Pennsylvania, where developers are seeking to bring to market more production from the Marcellus shale gas formation in northern Pennsylvania by pipeline and rail.

“They’ve been trying to stealth this through the permit process” to avoid inciting a backlash from neighbors along what would be an LNG transportation corridor to the port, said Jeff Tittel of the Sierra Club’s New Jersey chapter.

Opponents of the Gibbstown project draw a line between an LNG production facility in Bradford County, Pa., that will have capacity up to 3.5 million gals. While the Gibbstown planning document mentions receiving liquids by truck or rail, activists admit they have not yet figured out how the fuel would be moved.

“We just don’t know,” said Carluccio .

The project has support from southern New Jersey political leaders, including Democratic state Senate president Steve Sweeney, who is closely allied to regional labor and maritime groups.

Redeveloping waterfront facilities along the Delaware is a perennial favorite cause in those circles – and even one where industry and environmental groups can agree. Both sides are big boosters of calls for making the port of Paulsboro a hub for building offshore wind energy projects, a keystone of Gov. Phil Murphy’s stated goal of achieving 3,500 megawatts of offshore power by 2030.