Digging Deep for a Cleaner Rhode Island

At 252 feet below the surface of Providence, the "most important construction project you'll never see" will eventually mean a lot less sewage in Narragansett Bay.

06/15/2003

BY PETER B. LORD
Journal Environment Writer

PROVIDENCE -- To get to the job site of Rhode Island's most expensive public-works project, workers climb into a yellow steel cage slightly larger than a telephone booth and hold on as a crane swings them over and lowers them into a 50-foot-wide hole, so deep the sun doesn't reach the bottom.

The cage descends quickly. At 160 feet, concrete walls give way to wet rock walls. From machinery in the darkness below rises a metallic roar that forces the workers to squeeze yellow plugs into their ears.

At 252 feet below ground level, the cage hits bottom -- a dark, wet place, eerie with floodlights illuminating pools of water and glistening rock.

Pumps force air down in such prodigious quantities that wind gusts churn, dripping water into a swirling mist. Water pumps and a rock-drilling machine, called a "two boom drill jumbo," blast so loudly that if you pull out your earplug to listen to a question, your eardrums hurt.

It is here, a block from the Narragansett Bay Commission's Fields Point Wastewater Treatment Facility off Allens Avenue, that sandhogs and engineers drilling Rhode Island's massive combined sewer overflow tunnel literally turned the corner recently.

They finished drilling down into bedrock and are now beginning a 3-mile horizontal tunnel heading north, which will eventually run under downtown Providence to The Foundry near Providence Place mall.

The Bay Commission now spends $1 million a week on this vast hole in the ground.

The commission has invited the state's congressional delegation, Governor Carcieri, and numerous local officials to the work site tomorrow at 2 p.m. It plans to show them what's going on and to inaugurate the massive, 690-ton tunnel boring machine that will do most of the heavy drilling.

Another goal is to make another pitch for more federal money to help pay for the project.

The U.S. Environmental Protection Agency, in the 1980s, ordered the state to fix the metropolitan area sewer overflows that close shellfish beds and pollute Narragansett Bay each time it rains.

The project's first phase -- including this tunnel to collect overflows -- is expected to cost $314 million.

But so far, the federal government has contributed only $6.5 million.

PAUL PINAULT, the Bay Commission's executive director, has made numerous trips to Washington to lobby for more money.

"Our water and sewer infrastructure, like our highways and airports, provide benefits that go beyond local boundaries. But unlike highways and airports, clean water has no dedicated federal source of funding," Pinault said recently.

"Thirty years ago, the federal government funded 75 percent of the costs to maintain necessary clean water infrastructure; now, it provides less than 5 percent, leaving 95 percent to the local communities. The result is a funding gap that has been estimated at $46 billion per year [nationally] for necessary and mandated water and wastewater infrastructure."

Locally, the gap is closed with some help from the state, which has chipped in $26 million in general obligation bonds and $57 million from the state Clean Water Finance Agency. But neither is enough. The Bay Commission plans to borrow heavily and pay off the debt by increasing sewer rates it charges to 360,000 customers in nine communities.

The communities are Providence, Johnston, Central Falls, North Providence, Pawtucket, Cumberland, Lincoln and portions of Cranston and Smithfield.

Last fall, the Bay Commission proposed a 31-percent rate increase, largely to help pay for the CSO project and other capital improvements. The proposal would raise the $201 average rate for a homeowner by $65 a year, if approved by the Public Utilities Commission.

The proposed increase would come on top of a 25-percent increase a year ago and another 24 percent a year and a half before that.

Bay Commission officials say the rates are modest considering those charged by many other sewer districts. But the increases are still big, and in many cases, they are being imposed on people with modest incomes in urban neighborhoods.

What's more, critics say, much of the cost will be placed on urban residents while many of the benefits will go to everyone using Narragansett Bay.

Pinault argues that the environmental and public-health benefits alone make the CSO project the state's "most important construction project you'll never see."

For the next few months, the tunnel workers known as sandhogs will use the "two boom drill jumbo" and explosives to extend the tunnel several hundred feet, so the tunnel boring machine can be set up and put to work.

LAST WEEK, in the gloomy tunnel deep underground, a machine operator munched on a sandwich as he guided the machine to drill holes along a semicircle painted on the rock ahead.

The diameter of the tunnel will be 30 feet, but for now, crews are excavating the top half of the circle. They work around the clock, five days a week. They drill holes 8 to 10 feet deep, pack them with explosives, and blast.

Payloaders shovel the rock into steel boxes the size of small trucks. They're called muck buckets. The crane lifts the muck buckets out and empties the contents into trucks. For now, the rock is being used for fill on the Route 195 relocation project.

But to fully excavate the tunnel, some 750,000 cubic yards of rock must be removed, so other destinations are being sought.

By October, the initial stretch of tunnel should be long enough for the tunnel boring machine to be lowered and assembled.

Much of the machine was manufactured in Japan by Hitachi Zosen to specifications set by Michael L. Shank, the lead contractor, who has been drilling deep rock tunnels for decades.

Sixty three cutter discs project from the 30-foot face of the machine. Each steel-alloy blade looks like a railroad wheel. The wheels are smooth, not sharp.

Contrary to what some think, the machine doesn't cut or drill into the rock, according to John Kaplin, resident engineer for Gilbane Construction, project manager. It fractures the rock by scoring its surface under high pressure.

Dozens of motors power the cutter head. Each motor is held in place by bolts so big that two men wielded a giant ratchet wrench to turn them tight.

Workers last week painted hundreds of feet of so-called trailing gear, which will collect rock fragments and carry them to the machine's back end.

For this project, Shank plans to lay railroad track on the tunnel floor. Railroad cars will carry rock fragments back to the vertical shaft. Returning cars will carry a total of 16,000 pieces of concrete panels, each 22 feet long, 10 inches thick and 4 feet wide.

Each panel will cover one-quarter of the tunnel's circumference. After each four pieces are fitted in place, a jack will be spread between the top two pieces, snugging them up. The concrete segments are being fabricated in Cranston.

The tunnel is designed to hold 62 million gallons of the sewage-rainwater mix that would otherwise overflow sewer lines and flow into the Woonasquatucket and Providence Rivers. It will collect 95 percent of the overflows in downtown Providence, and 40 percent in the overall system.

Two other vertical shafts have been dug nearby. They will lead to a gymnasium-sized underground cavern that will house giant pumps designed to carry the sewage up to the treatment plant.

On Ernest Street, a block from Allens Avenue, a small industrial city has risen around the holes -- machine shops, refrigeration plants to freeze the ground and prevent cave-ins, towering cranes, dozens of railroad cars, stacks of railroad rails.

"Nothing about this job is small," says the Bay Commission's project engineer, Richard Bernier, as he walks among the equipment.

The tunnel boring machine will grind out the tunnel directly under downtown Providence during the next two years, but project directors say no one should feel a thing. The tunnel borers will keep plenty of bedrock over their heads.

 

State officials take tour of sewer tunnel project
 

06/16/2003

The Associated Press


Posted 4:54 p.m.
PROVIDENCE -- State officials toured the construction site of the Narragansett Bay Commission's combined sewer overflow project today.


The 20-years-plus, $700-million project to improve water quality in Narragansett Bay includes a 16,000-foot-long tunnel.


At the site, lawmakers and others donned hard hats during the inauguration of a 30-foot-tall, 255-foot long tunnel boring machine, which will drill the main tunnel that's the project's centerpiece.


The tunnel project, which costs $314 million, is the first phase of a larger plan to bring Rhode Island into compliance with the federal Clean Water Act.


Narragansett Bay Commission Chairman Vincent Mesolella said the plan will not turn into another version of Boston's downtown highway project, the so-called "Big Dig," which has been plagued with delays and rising costs.


"I will, with every ounce of my being, watch and maintain this budget so there's no cost anticipated that shouldn't be anticipated," he said.