Weaver’s Cove Energy said yesterday it has officially asked the Federal Energy Regulatory Commission (FERC) for approval to build a liquefied natural gas offloading facility in the middle of Mount Hope Bay.

Friday’s filing was not unexpected. The company has been saying since March that it was going to try for the development of what it characterizes as an “offshore” facility after it became apparent that it was not going to be able to build one in Fall River, at least as long as the old Brightman Street Bridge remains intact.

That bridge was supposed to be demolished. But officials have arranged to keep it intact, specifically to block Weaver’s Cove’s plans.

FERC gave its blessing to the original proposal in 2005, two years after plans were announced. Permission has been extended to 2015 in case the Brightman comes down, said company spokesman James Grasso. The original expiration date had been next year.

The new $700-million offshore proposal, which requires a full range of federal, Massachusetts and local approvals, is the backup plan. It would allow 950-foot-long supertankers to berth in the middle of Mount Hope Bay after a trip up Narragansett Bay, passing beneath the Pell and Mount Hope Bay bridges in the process. Once parked, the tankers would unload their supercooled fuel to a platform. The LNG would then be piped underground through four miles of specially insulated piping to a Fall River storage facility.

Opposition to the original proposal had been widespread, in part because of concern that if a tanker were to rupture or be sabotaged, creating a meter-wide hole in the hull, ignition of the fuel would give someone standing a half-mile away blistering burns in as little as 40 seconds.

Under the new plan, the three-tier berthing platform for the supertankers, measuring 125 feet by 250 feet, would be embedded in the sediment and rock in waters within the Town of Somerset, about one mile from the nearest shoreline and two miles south of the Braga Bridge.

“We listened to the concerns expressed by the public and local politicians and this proposal, although costing significantly more than the earlier one, represents answers to those concerns,” said Weaver’s Cove CEO Gordon Shearer in a statement announcing the FERC filing.

“If he listened to what the people were saying, they would just go away,” said Joseph Carvalho of the Coalition for Responsible Siting of LNG Facilities. Because the company has said it will go with its original plan if it can, saying that Weaver’s Cove is listening to the public “is disingenuous at the very least, and scurrilous at the worst.”

Officials in Massachusetts and Rhode Island have been widely opposed to both plans.

“This is just buying time,” said Carvalho. “This is to placate the shareholders, stockholders and everybody else until they think they can get the old bridge down.”

Grasso said the approval process will probably take a year or so. Construction would consume about three years.

“In the meantime, this project will generate over 1,000 new jobs,” said Grasso. It would also make Weaver’s Cove the largest taxpayer in both Fall River and Somerset.

The company says the facility would have 50 permanent workers, create 400 jobs, and be worth $100 million per year to the region.

The new plan would be more expensive because it requires more than four miles of high-tech underground pipeline, buried at least five feet deep in a trench, to carry the fuel beneath the Bay and Taunton River to Fall River.

But it would also require less dredging and, according to Weaver’s Cove, “substantially reduce the impact on fish and other aquatic life” in Mount Hope Bay and along the Taunton River.

gemery@projo.com