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The Narragansett Bay Commission’s replacement of its century-old sewer and water runoff infrastructure below ground is nearing completion after more than 20 years of work
After decades of work, light at end of CSO tunnel
BY MARY MACDONALD | MacDonald@PBN.com
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WHAT HAPPENS BENEATH the streets of Providence and surrounding cities is unseen by residents, but after heavy rainfall, the result always ends up in nearby rivers and Narragansett Bay.
For decades, following storms, the street drains and sewers that are part of the city’s underground infrastructure had overflowed, discharging untreated water into waterways. A massive undertaking begun more than 20 years ago by the Narragansett Bay Commission, to replace its century-old sewer and water runoff infrastructure below ground, has entered a final phase.
In late June, the commission started construction of the third and final tunnel that will capture as much as 58.5 million gallons of this mixed overflow and retain it so it can be safely treated before discharge. The final phase of the Combined Sewer Overflow Abatement Program affects the Seekonk River, which flows into Narragansett Bay and includes communities such as East Providence, Pawtucket and Providence.
The planning for the program dates in the early 1990s. Officials say the first two CSO storage tunnels dug with massive boring equipment – one completed in 2008 and the second in 2014 – have been a huge success. The first tunnel has prevented about 1.1 billion gallons of wastewater from flowing into the bay before being treated, according to NBC.
Tests have shown that pollution levels in the bay have dropped to the point that shellfish beds near Providence have been opened for the first time in decades.
But the Seekonk River remains a source of pollution, particularly after heavy rainstorms.
Upon completion, the third tunnel is expected to further reduce the frequency of closures of shellfish beds.
For the project engineers, the final phase marks the end of a long-term commitment.
They have designed the Pawtucket tunnel, a 2.2-mile-long, 30-foot-wide tunnel that will run below Pawtucket and Central Falls.
The $450 million construction project is being handled through a design-build contract that includes CB3A, a U.S.-based subsidiary of a French construction and engineering firm, and Massachusetts-based Barletta Heavy Division Inc.
The tunnel is expected to be completed in 2027. It will replace a system that now relies on piping that combines sewer discharges from homes and businesses and runoff from roads, buildings and other impervious surfaces, according to Jamie Samons, NBC public affairs officer.
“This was great technology in 1872, but in 1972, under the federal Clean Water Act, all of those became illegal,” she said of the original systems.
From an engineering standpoint, the challenge of the latest phase included finding cost savings that would not hurt the responsiveness of the new
DIGGING IT: Workers for the contractor CB3A start working on the main shaft of the combined sewer overflow tunnel that will run more than 100 feet below the city of Pawtucket. The shaft, located on School Street in Pawtucket, will be 60 feet in diameter and will allow a boring machine to be lowered in.
COURTESY NARRAGANSETT BAY COMMISSION/PETER GOLDBERG
system, according to Melissa Carter, a vice president at Stantec Inc., the Canadian company leading design and engineering on the project since 2014.
“The main challenge was trying to optimize the plan,” Carter said. With phase three, engineers examined earlier models and started revising the plan to try to minimize costs. “We really wanted to look at minimizing cost but getting as much out of the existing performance system as we could,” she said.
One of the results of those engineering changes was a decision to raise the final tunnel by 25 feet. It will now run from about 115 feet to 155 feet deep, sloping to a pumping station that will then deliver untreated water to the Bucklin Point Wastewater Treatment Facility in East Providence.
To determine whether such changes would work, engineers used a digital modeling tool, called a digital twin, and went into the field to capture real-time data following storms. They were able to determine whether the modified system would work under various conditions.
Tunnel projects are always challenging, Carter said, because engineers can’t “see” underground. To determine the conditions, the engineering companies involved in the project, including Pare Corp., of Lincoln, took deep-rock borings several hundred feet apart all along the proposed route “to
try to characterize the rock as much as we can,” Carter said.
That process took about two years, according to Brandon Blanchard, managing engineer for Pare.
Providence is among many communities in the country that have embarked on the combined sewer overflow systems, Blanchard said. Similar efforts have been undertaken in recent years in Boston, in Hartford, Conn., and in New York and Philadelphia. Each system is unique, however, as the soil and setting conditions differ.
Before the first CSO tunnel was completed, Samons said, the Narragansett Bay Commission’s system had 75 to 150 sewer overflows a year. The goal of the program is to provide enough underground storage to capture the flow from a threemonth storm, one that could drop as much as 1.65 inches of rain in six hours.
“So the goal, at the end of the program, is we see only a few overflows each year,” Samons said.
When construction of the connection to the existing sewers begins, vertical shafts will be created using controlled blasts. But people above ground should not feel much of that, given the depth, Carter said.
A tunnel boring machine, with a diameter of 30 feet, will slowly drill through the earth to clear the space for the tunnel itself, continuously grinding the rock in front of it, Carter said.
The third tunnel will have a wide impact when completed, Carter said. “Not just to the environment but to the community,” she said. “Even though it is a long-term project and seeing the payoff is not going to be immediate, at the end of the day it’s very rewarding.” n
FOCUS | EDUCATION
JOB TRAINING
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employees to large employers such as CVS Health Corp. and Fidelity Investments Inc.
“Woonsocket is often underserved – its unemployment rate is typically at least one or more percentage points higher than the state average,” said Amy Grzybowski, the director of the Westerly Education Center who is also expected to direct the northern Rhode Island center. “It is an opportune spot, not only for the people but for the employers.”
The R.I. Office of the Postsecondary Commissioner is set to lease and build out a 14,700-squarefoot space on the third floor of a partially vacant building at 95-117 Main St. in Woonsocket that decades ago played a central role in the mill city’s commercial district.
The project will cost about $4 million to $5 million, which includes the cost of operating for the first year, according to Grzybowski. More than $2 million has been donated by private entities and anonymous donors.
The center, which will feature a mock CVS store, classrooms, computer laboratories, a customer service center and customized space for hands-on, industry-ready training programs, is expected to open in late 2021 or early next year. The name of the center has not been finalized.
Grzybowski said the goal is to serve 500 people at the center in the first year, and enrollment is expected to grow after that.
“Rhode Island businesses, especially those located in northern Rhode Island, have had an urgent need for employees, and even more so now after the pandemic,” she said. “We will help transform the workforce there from some soon-tobe obsolete jobs, to more longer-term and lucrative career pathways.”
The Woonsocket center will follow the blueprint of the Westerly Education Center, which partners with private companies and the R.I. Department of Labor and Training to offer workforce development training and classroom space for the University of Rhode Island, Rhode Island College and the Community College of Rhode Island.
The origins of the Westerly center can be traced back to a conversation between state Rep. Samuel A. Azzinaro, D-Westerly, and developer Charles Royce.
“Out of the blue, he said, ‘You know what this town needs is a community college in downtown Westerly,’ ” Azzinaro said of his initial talk with Royce. “He’s a very educated-minded person, and he loves community colleges.”
Azzinaro liked the idea, thinking that a higher education center in downtown Westerly would complement Royce’s efforts to preserve the area’s character. Royce, one of the partners behind the rebuilding of the Ocean House in 2010, offered $2 million as startup funding. State leaders said they’d get on board if the facility included job skills training.
WORK SITE: Amy Grzybowski, future director of a planned higher education center in northern Rhode Island, visits the building in downtown Woonsocket that will be converted into the center by late 2021 or early 2022.
PBN PHOTO/MICHAEL SALERNO
General Dynamics Electric Boat, which employs thousands in North Kingstown, was identified as an employer needing to bolster its workforce, and the company signed on to develop a curriculum based on the skills it needed from workers. A new building was constructed on 2½ acres on Friendship Street in Westerly.
“What was born was the Westerly Education Center,” said Grzybowski, who has served as its director since 2017. She is also executive director of the Office of the Postsecondary Commissioner’s R.I. Higher Education and Industry Centers.
Grzybowski said the Westerly center has delivered better results than anticipated, putting 6,000 employees into the workforce at Electric Boat over more than four years.
It’s hoped the Woonsocket postsecondary center, which has been in the works since 2018, will also unite employers with educators to bolster the regional workforce and its economy.
Woonsocket Mayor Lisa Baldelli-Hunt said the center’s location in the commercial district is vital to bring back the city’s economy and its workforce, which had been hurt by the pandemic.
“We all know that for many years across the state and across the country that main streets have been darkened. It’s not the 1950s and ’60s when things were bustling,” she said. “And our main street was challenged, like many others.”
Azzinaro agreed that these types of centers can be helpful in building a workforce decimated by the pandemic. “We have got to get people back to work. Everybody is looking for help. Everywhere you go, there is a sign on the door – help wanted,” he said.
The state’s public colleges will offer courses throughout the year in Woonsocket, ranging from general education to graduate level. GED courses will also be provided by a local education organization. Private businesses and organizations will be able to rent classrooms for training or meetings.
The Woonsocket center’s employer partners will be AAA Northeast, CVS and Fidelity. Its state partners are the DLT, the R.I. Department of Education, the R.I. Executive Office of Commerce and the Governor’s Workforce Board. “What is neat about working for the office of postsecondary is we can kind of be the hotel of the higher ed workforce opportunities so that we can meet the demand of the employers,” Grzybowski said. n
