Big ships, a deeper channel
Massport examines dredging project
By Beth Daley, Globe Staff | May 29, 2006
The Massachusetts Port Authority wants to deepen the 11-mile shipping channel into Boston Harbor to accommodate large cargo ships, a project that would move nearly 60 percent as much earth as the Big Dig.
The operator of the Port of Boston and the Army Corps of Engineers are close to finishing a four-year, $4 million study evaluating the economic feasibility of digging down through 5 to 10 feet of clay and rock to deepen the channel to 45 to 50 feet. The project, estimated at about $100 million, would have to be authorized by Congress, because the federal government would pay half the cost. The work would take about four years to complete and would not interfere with shipping.
``Our 40-foot channel puts us at a competitive disadvantage," said Mike Leone, Boston's port director. ``The next generation [of cargo ships] is coming in deeper."
Already some ships must ride the high tide to enter the harbor, and the Coast Guard is investigating whether a container ship scraped the channel bottom off Spectacle Island this winter -- possibly a sign that ships could ground there in the future.
Worldwide port trade is expected to double by 2020, and cargo ships are being built larger to transport more goods and take advantage of the economies of scale. Cruise ships are also getting bigger. As a result, more than 25 ports in the United States are either expanding their channels or considering such projects, according to the American Association of Port Authorities. Both New York and Los Angeles are going to 50 feet deep. Congress has already appropriated money for some of these projects.
``It's a challenge for every port to get funding," said Leone, who said that the Massachusetts congressional delegation has been supportive of port projects in the past. He said he expects it will support this one.
A Coast Guard spokesman in Boston, Lieutenant Greg Callaghan, said his agency supports dredging to improve navigation safety.
Massive public works projects under Boston Harbor became feats of engineering in the 1990s, with a tunnel bored through bedrock to build Deer Island's 9 1/2-mile sewage pipe and massive amounts of dredging to make room for the Big Dig's Ted Williams Tunnel .
But digging a deeper shipping channel would be the biggest single dredging operation in the harbor since the 1940s, when it was widened, according to the Army Corps of Engineers. The new project would involve dredging about 10 million cubic yards of clay and mud -- enough to cover an area the size of Boston Common, 12-feet deep. By contrast, the entire Big Dig dredged or excavated about 17.6 million cubic yards of material.
The study is examining deepening the harbor's entrance channel, which is 1,500 feet wide; the main shipping lane, which is 1,200 feet wide; and the Chelsea River.
The work would not extend into the inner harbor because the Ted Williams Tunnel and the MBTA Blue Line are in the way.
The new project also will not affect several tributaries of the harbor that were dredged five years ago to bring them to the harbor's current depth.
The material to be dredged appears to contain few contaminants. Army Corps of Engineers tests indicate that the Boston blue clay under the channel floor that will be dug up has been untouched by hundreds of years of industrial pollution. That means it can be safely dumped in Massachusetts Bay at a federally designated disposal site about 23 miles offshore.
``It's virgin material that has never been exposed," said Michael Keegan, the Army Corps project manager.
Still, environmentalists and fishermen are concerned about the project's impact, particularly on fish migration.
``We want them to avoid our gear. . . . We want them to let fishermen know where they are going to be," said Bill Adler, executive director of the Massachusetts Lobstermen's Association.
Traps are not supposed to be set in the shipping channel, but lobstermen place them around its perimeter.
This summer, a separate, $40 million maintenance dredging project will begin in the channel that will scrape off sediment carried into the harbor by the Chelsea and Mystic rivers.
That material is considered unsuitable for the offshore disposal site because of high levels of some chemicals. It will be buried under the main shipping channel and the Mystic River and capped with sand.
The Port of Boston has undergone a transformation since the mid-1990s, when it was facing major financial problems from falling cargo volumes.
Since then, Massport has invested $50 million to upgrade facilities and is currently building a $25 million expansion to South Boston's Conley Terminal.
It has attracted more Chinese shipping lines to come here directly from Asia and has attracted more cruise ships to the Black Falcon terminal.
Between May 2005 and last month, 256 container vessels visited Conley -- a 9 percent increase over the previous 12 months -- and the number of cruise ship passengers increased 18 percent during the same period.
But specialists say if Boston's shipping channel does not get deeper, bigger ships will go to naturally deeper ports, such as Halifax, Nova Scotia, or to cities that have already invested in deepening projects.
Beth Daley can be reached at
bdaley@globe.com.
