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$123M Boston Harbor Dredging Project Deepens Channel for Larger Ships

August 16, 2018 | Lori Tobias | Website

Work on a $123 million dredging project in New England's largest seaport is under way, with plans to continue for about three years to deepen the project to its newly authorized depths.

The dredging project in the Boston Harbor is designed to accommodate large container ships that are calling on the United States' east coast now that the Panama Canal improvements are completed, according to the U.S. Army Corps of Engineers.

The contract was awarded to Cashman/Dutra, joint venture of Quincy, Mass., in February 2017, but delayed due to a GAO protest which was resolved in late spring.

Approximately 11.7 million cu. yds. of silt, blue clay, till and weathered rock will be dredged to improve the harbor project, including: deepening and widening the Broad Sound North Channel to -51 ft. Mean Lower Low Water (MLLW); deepening and widening the Main Ship Channel to the Conley Terminal, including the turning basin to -47 ft. MLLW; and deepening the President Roads Anchorage and the lower Reserved Channel to 47 ft. MLLW.

The dredged material will be offloaded at the Massachusetts Bay Disposal Site, approximately 20 mi. offshore of Boston Harbor, with the exception of a small fraction of the material being utilized as a cap to the Main Ship Channel Confined Aquatic Disposal cell, downstream of the inner confluence of the Chelsea and Mystic Rivers.

More than 87 percent of Boston Harbor commerce is the receipt and shipment of petroleum products. Principal commercial traffic consists of the import of distillate petroleum products, residual fuel oil, sugar, limestone and lumber; the receipt and shipment of other petroleum products; and the export of iron and steel scrap.

The initial work in the Boston Harbor began shortly after the Civil War, according to the Corps. The most recent improvement work was completed in May 1966. The current project includes the harbor proper and four access channels: the Chelsea River, the Fort Point Channel, the South Boston Reserved Channel, and the Weir River at Nantasket Beach.

The Corps describes the project in detail below:

The Harbor Proper

Work by the Corps in the harbor proper consists of:

  • A 6-mi.-long, 40-ft.-deep main channel extending from Massachusetts Bay, through Broad Sound, to the entrance of Mystic and Chelsea Rivers. The channel is 900 to 1,100 ft. wide from the sea, through Broad Sound, to President Roads, and 600 ft. wide from President Roads to the entrance of Mystic and Chelsea rivers.
  • A 35-ft.-deep channel that runs parallel to, and on the northerly side of, the main 40-ft.-deep channel. The 35-ft.-deep channel is 600 ft. wide and extends from the sea, through Broad Sound, to a point opposite the fish pier.
  • A 2-mi.-long, 35-ft.-deep channel that extends from an area abreast of Fort Point Channel to a point almost one mile past the Chelsea Street Bridge. The channel, which has widths varying from 100 to 1,000 ft., starts in the harbor in front of Fort Point Channel and adjacent to the 40-ft.-deep channel. It extends down the harbor parallel to the 40-ft. channel, past the Mystic River Bridge, except the portion in front of the former Charlestown Navy Yard which was de-authorized by Congress in 1992, and ends at the General Andrew P. McArdle Bridge at the entrance to the Chelsea River. The channel also splits at the Navy Yard and goes down the Charles River before ending at the Charlestown Bridge.
  • A 2-mi.-long channel 30 ft. deep and 1,200 ft. wide from the sea through Broad Sound to President Roads. This channel is situated south of the 35 and 40-ft.-deep Broad Sound channels.
  • A 3-mi.-long channel 27 ft. deep and 1,000 ft. wide extending from Nantasket Roads through the Narrows to President Roads.
  • A 550-ft.-long stub channel, 15 ft. deep and 300 ft. wide, located at the northeast head of Long Island in the vicinity of Nix's Mate Shoal.
  • An approach channel (not originally built by the Corps) to the former U.S. Navy Drydock Number 3 in South Boston that was deepened to 40 ft.
  • A 40-ft.-deep anchorage along the northern limit of President Roads. The anchorage, 350 acres in area, measures 6,200 ft. east to west and 2,500 ft. north to south.
  • A 35-ft.-deep area lying west of the anchorage.
Stone seawalls that protect the harbor's exposed headlands and islands.
Chelsea River Channel

The percentage of traffic passing through the Chelsea River has been increasing over the past several years. A recent study indicated that 46 percent of the traffic in Boston Harbor utilized the Chelsea River.

The Corps' work on the Chelsea River includes a main ship channel 1.8 mi. long extending from the Gen. Andrew P. McArdle Bridge to the end of the Chelsea River. From the McArdle Bridge to the Chelsea Street Bridge, the channel is 35 ft. deep and approximately 225-250 ft. wide. From the Chelsea Street Bridge to a point near the river's end, the channel is 250-430 ft. wide. At the end of the channel there is a turning and maneuvering basin 35 ft. deep and approximately 800 ft. wide and 1,000 ft. long.

Fort Point Channel

The Fort Point Channel extends from Boston Harbor to the Northern Avenue Bridge in South Boston, a distance of about 1,000 ft. It is 23 ft. deep and 175 ft. wide.

South Boston Reserved Channel

The Reserved Channel extends from the 40-ft.-deep channel in Boston Harbor to the L Street Bridge in South Boston, a distance of about 5,400 ft. It is 35 ft. deep and 430 ft. wide

The Weir River at Nantasket Beach

The 1.7-mi.-long channel in the Weir River, 12 ft. deep and 150 ft. wide, provides access to the Nantasket Beach terminal in Hull. The channel extends from Sunset Point on Nantasket Beach, through the Weir River, to Nantasket Pier.