PORTLAND — Like a slow-draining sink, Portland Harbor needs a good scouring now and then.
Beginning this November, for the first time in 14 years, the harbor will get one.
The U.S. Army Corps of Engineers has hired a Massachusetts company to mechanically dredge about 700,000 cubic feet of sediment, rock and other material from the bottom of the channel between Portland and South Portland.
The $9.2 million project is expected to be complete by March 2014.
The harbor was last dredged in 1999, and the timing between these “maintenance” dredges is typical, according to Jack Karalius, the project manager for the Corps. The dredging will restore the channel to a minimum depth of 35 feet, the level required for much of Portland’s busy ship traffic.
In five spots, rock pinnacles that extend above that limit will have to be drilled or blasted away.
“With so many large ships coming in and out of Portland, it’s absolutely critical to have a navigable harbor,” U.S. Rep. Chellie Pingree, D-Maine, said in a prepared statement. “The cruise ships, tankers, fishing boats, cargo freighters, and more that bring millions of dollars into the local economy every year depend on a deep port.”
The Portland dredging is one of the Corps’ largest such projects in New England, according to Karalius. Most other dredging work involves smaller harbors that are used primarily for recreation, such as Wells Harbor, where the Corps is also planning to dredge this fall.
All the material removed from the harbor will be dumped about 10 miles offshore. Karalius said the debris isn’t hazardous, but can’t be reused. “Mostly it’s fine-grain silt, but that isn’t suitable, for example, to rebuild beaches,” he said.
And while it’s impossible to predict exactly what else the dredging may uncover, Karalius said he expects few surprises.
“We don’t think we’ll be turning up abandoned automobiles,” he said.