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Crews Dig Tunnel to Capture Raw Sewage Now Spilled Into Bay

Moving in advance for release in weekend editions of Dec. 11-13 and thereafter

By RICHARD C. LEWIS

Associated Press Writer

PROVIDENCE, R.I. (AP) - Like some advanced race of moles, crews are boring a 3-mile-long tunnel under Rhode Island's capital city. It is this state's largest public works project to date, and will capture raw sewage that is now jettisoned into waterways during heavy rains. All it takes is a half-inch of rain to overwhelm the aged combined sewer and stormwater system -- some segments 134 years old -- that serves 360,000 residents of metropolitan Providence.

To relieve the backup, the contaminated water is released into local rivers, such as the Blackstone, Moshassuck, Providence, Seekonk and Woonasquatucket rivers. Those empty into Narragansett Bay, fouling the water with fecal coliform bacteria and forcing the closure of shellfish beds that are a lifeblood of the commercial fishing industry.

The $318 million Combined Sewer Overflow Abatement project is Rhode Island's effort to stem the spills and clean the water. Work on the first phase of the Narragansett Bay Commission's (NBC) project began in May 2001, and is scheduled to be completed in spring 2008. Two other phases are planned, which would involve building another miles-long underground tunnel.

Vincent Mesolella, NBC chairman, called the Providence tunnel "a subway for water" that will improve the bay's health.

"It's absolutely critical," he added.

Scientists agree that the project will greatly reduce dangerous bacteria from local waters, but don't think it will meet federal requirements for the water to be fishable and swimmable.

"I would definitely not say outright this will make (the bay) fishable, swimmable, but this is certainly a major step, the major step," said Amos Colt, assistant director with the Rhode Island Sea Grant College Program, a partnership among federal and state agencies and universities to research marine issues.

The fishable, swimmable mandate comes from Congress, and is the reason why the commission looked at the problem in the first place. Other major cities with shared sewer and stormwater pipes also have opted to construct tunnels to capture excess wastewater. They include Boston, Chicago, Portland, Ore., and Milwaukee. Atlanta, Detroit, St. Louis and Washington plan similar, multi-billion dollar projects.

"It is an excellent solution, a proven technology," said Alexandra Dunn, general counsel for the Association of Metropolitan Sewerage Agencies in Washington.

There are 745 communities in the United States with combined sewer systems, most of them older cities concentrated in the Northeast and Great Lakes regions, said Jim Hanlon, director of office of wastewater management at the Environmental Protection Agency. As of July, about 59 percent of those municipalities have adopted solutions and are starting construction, he added.

"We're making progress," he said.

Newer communities have separate sanitary sewer and stormwater systems.

In Rhode Island, the tunnel under construction will stretch from the Field's Point wastewater treatment plant to a foundry complex just west of downtown. Its route roughly follows existing pipes along the Providence and Woonasquatucket rivers, then branches out under the south lawn of the Statehouse before ending at the foundry complex, where one of the most active outfall pipes is located.

Engineers will close the outfall points and connect them to the current combined sewer network. The crews also will build "drop shafts" that will carry the excess wastewater downward to the new tunnel. The wastewater is then held in the 30-foot diameter tunnel, lined with concrete, until the Field's Point plant can process it.

Environmental officials estimate about 2.2 billion gallons of untreated water is released annually into local rivers. The tunnel will be able to hold up to 65 million gallons, good enough to hold overflows except in the heaviest rains, expected about four times a year.

While ridding the water of disease-carrying bacteria, the project is expected to allow shellfish beds in upper Narragansett Bay to open for longer periods.

Currently, 11,000 acres in the upper bay can be closed when rainfall exceeds a half-inch. That area, a line roughly from Conimicut Point in Warwick to Nayatt Point in Barrington southward to the northern tip of Prudence Island and over to Popasquash Point in Bristol, holds about 70 percent of the bay's shellfish harvest, according to Art Ganz, supervising biologist in the Fish & Wildlife division at the state Department of Environmental Management. Shellfish constantly filter water, so even those in the polluted areas can be harvested once the water turns cleaner, scientists say.

The shellfish industry has suffered due to the frequent closures, said Michael McGiveney, a shellfisherman from North Kingstown and president of the Rhode Island Shellfishermen Association.

"If you're a (shellfisherman), you need to have those grounds," McGiveney said.

Everyone agrees the project will allow the beds to be open more often, but it's unknown how much. Once the first phase is completed, the project will be halted for at least two years, so scientists can analyze how much the water has improved.

Two more phases are planned after that, possibly ending in 2020. They'd involve building more pipes connected to a second wastewater treatment plant at Bucklin Point in East Providence, and constructing another 3-mile tunnel from that plant to Central Falls. Total cost could reach $1 billion, said Jamie Samons, NBC's spokeswoman.

Samons assured the water then would be clean enough to fish and swim.

"That's what it's engineered to do," she said. "It's taking the dirty water, treating it, and making it clean."