Casco Bay Bridge this month will be opening more often to make way for a tugboat involved in the dredging of Portland Harbor.

The $9 million project was to begin late Friday night with one of the nation’s largest dredgers digging upriver from the Casco Bay Bridge.

The dredger, which uses a massive crane, will dump the sediment in a split-hull hopper barge. The Casco Bay Bridge must open to provide clearance for an ocean-going tugboat that will haul the barge out of the harbor and dump the sediment at a disposal site seven miles east of Cape Elizabeth. Bedrock ridges that surround the disposal site will contain the deposited sediment, according to the U.S. Army Corps of Engineers, which is funding the project.

The dredging was to begin at the uppermost navigable point on the Fore River for ships with deep drafts. Over the next several weeks, the dredger will work its way downstream toward the head of the river, according to Norman Bourque, project manager for Cashman Dredging, the contractor.

The project, which will assure depths of 35 feet at mean low tide in the shipping channel, is the first maintenance dredging of the channel in 15 years.

The dredger, the Dale Pyatt, is equipped with a crane and a giant bucket that can lift 50 cubic yards of sediment with each scoop. The crane is powered by four Caterpillar diesel generators. The dredger’s bucket is composed of clamshell-shaped attachments that dig from two directions, scooping up mud and waste in between.

Built last year, the Dale Pyatt was named after the president of the company, which is based in Quincy, Mass.

From Friday night until Feb. 13, the Casco Bay Bridge will have up to four additional openings within a 24-hour period, according to the Maine Department of Transportation. These are in addition to the normal openings when marine traffic passes under the bridge.

From Feb. 14 through Feb. 21, random openings will occur as work requires.

From Feb. 22 through Feb. 26, there will be approximately eight additional openings within each 24-hour period.

After Feb. 26, the balance of the work will be away from the Casco Bay Bridge.

Officials with the dredging company said they will make every effort to schedule these openings outside of the commuting times of 7 to 9 a.m. and 4 to 6 p.m.

“We are working with Maine DOT to minimize the impact as much as possible,” Bourque said.

At the end of next week, Bourque said, crews will begin drilling through ledge at five high spots in the channel and setting off underwater explosives. The ledges are located in the channel between DiMillo’s floating restaurant and the Coast Guard base in South Portland.

Three tugboats are involved in the dredge operations. The work is labor-intensive. The dredging company has 10 managers and 35 to 40 workers on site.

In addition, the drilling and blasting operations will have two managers and 15 workers, Bourque said.

Bourque said he is confident that the work can be completed before the March 15 deadline. By state law, the project must be completed by then to avoid interfering with the lobster fishery, which begins in the spring.

Tom Bell can be contacted at 791-6369 or at:

tbell@pressherald.com