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.
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 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
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
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
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
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
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
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
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
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
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
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
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
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
"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.