CONCORD — A California company is the apparent low bidder for the job of dredging the Merrimack River channel and renourishing the beaches at Plum Island and Salisbury.

AIS Construction of Carpinteria, Calif., quoted a price of $3.25 million for the project, well below two other bids submitted yesterday at the U.S. Army Corps of Engineers New England District office in Concord.

The AIS bid is also within the Army Corps guidelines as being no more than 25 percent higher than the government's own estimate.

Although the figure that has been discussed for several months is $4.1 million, the Army Corps' official estimate was $2.923 million, so the AIS bid was 11.2 percent higher.

Rachel Raposa, chief of the Army Corps Contract Branch, said it will take about two to three weeks to review AIS's qualifications and equipment, and to award a contract.

Cashman Construction of Quincy was the second low bidder at $6.998 million, and Great Lakes Dredge and Dock Co. of Oak Brook, Ill., quoted a price of $10.184 million. Both of those bids were far higher than the Army Corps guidelines allow.

Yesterday's bidding continues the progress of the project, planning for which began in earnest just about a year ago.

If there are no problems in the meantime, work should begin in early January and be completed by the end of March.

The plan is to dredge the Merrimack River channel to a depth of 15 feet and deposit the sand directly onto the beaches at Plum Island and Salisbury.

The dredging operation is expected to yield up to 160,000 cubic yards of sand, 120,000 of which will go to Plum Island and the remaining 40,000 to Salisbury.

A 2,500-foot stretch of shoreline from Plum Island Center northward is the critical area for sand deposit. Beach erosion there is at its worst.

Almost exactly one year ago, a house at 16R Northern Boulevard was undermined so severely by the ocean that it had to be demolished.

Owners of other nearby buildings have had to dismantle decks when erosion destabilized them.

The beach renourishment is intended to buy some time while officials work to rectify what they believe is the root cause of the erosion problem, the deterioration of the stone jetties that define the mouth of the Merrimack River.

The north jetty extends seaward from the southern end of Salisbury Beach, and the south jetty extends from the northern end of Plum Island.

The south jetty in particular has been blamed for aggravating the island's erosion. A gap has developed in the massive stone structure that appears to channel water toward the island center in a motion that scours sand off the beach.

About a dozen Army Corps personnel waited in a conference room at the Concord office until Raposa closed the bidding at exactly 2 p.m.

She opened and read AIS's bid first, followed in order by Great Lakes Dredge and Dock's and Cashman Construction.

AIS is estimating that it will cost a little less than $1.574 million for dredging and depositing sand on Plum Island, another $235,200 for planting dune grass on the renourished beach and $77,000 to erect fencing around the area.

The company's estimate for dredging and deposit on Salisbury Beach is about $254,000.