PLUM ISLAND — It could all fall apart if the bids are too high, but otherwise Plum Island beach nourishment is a done deal.

A multi-agency task force that has spent a year planning the project ran through its to-do list yesterday and concluded that everything necessary to deposit up to 120,000 cubic yards of sand on the beach has been done.

Permits are in hand, easements have been recorded, a partnership agreement has been signed, funding has been secured and bid documents are being circulated.

So the Merrimack River Beach Alliance¬­ — a group of federal, state and local officials, and private stakeholders — is getting ready to start work on its next objective: repairing the stone jetties at Plum Island and Salisbury Beach.

The U.S. Army Corps of Engineers is seeking bids for a project that includes dredging the Merrimack River channel and depositing the accumulated sand on a 2,500-foot section of shoreline from Plum Island Center northward and on Salisbury Beach.

The dredging operation is expected to yield up to 160,000 cubic yards of sand, 120,000 for the island and 40,000 for Salisbury.

The budget for the work is $4.1 million. Bids will be opened Nov. 17, and a contract could be awarded within two to four weeks after that.

Army Corps representatives at yesterday's Beach Alliance meeting said work will begin in early January and must be completed by March 14. The contractor will be required to take all equipment off the beach by March 31. The following day marks the start of the nesting season of the piping plover, a bird species listed by the federal and state governments as "threatened."

The Beach Alliance is chaired by state Sen. Bruce Tarr, a Gloucester Republican whose district includes Newbury.

Tarr said the accomplishment of beach replenishment was the result of "unprecedented cooperation" among diverse elements with different missions.

"I'm very, very gratified," he said.

Erosion on Plum Island near the Center has accelerated since the Patriots Day storm of April 2007.

A house was lost a year ago when it was undermined by surging surf so badly it had to be demolished.

Replenishing the beach has been estimated to add as much as 70 feet of width to the shore.

An Army Corps study released in January concluded that as many as 26 properties would be in jeopardy over the next 10 years if nothing were done to stem the erosion. Part of Northern Boulevard would also be threatened, the study found.

While the beach renourishment project will take care of the immediate danger, it is not considered a permanent solution.

"What we've done here is buy a limited amount of time," said Mark Habel, chief of the Army Corps Navigation Section's Engineering and Planning Division.