A construction crew now is set to bore a massive tunnel near the Seekonk River in Pawtucket, R.I. in the third and final phase of Rhode Island’s “Big Dig.” The $1.5-billion Narragansett Bay Commission Combined Sewer Overflow (CSO) program is the largest single public works project in state history.
CB3A - 一家承包商CBNA的合资企业CBNA，美国法国巨头Bouygues和Barletta Construction LLC，马萨诸塞州广州，与AECOM合作，正在合作，估计在2027年完成估计的4.5亿美元的设计建造合同。最终阶段的首席设计师兼计划经理Stantec的一位女发言人说，该阶段开始于上个月，其中包括一个拦截门和筛查结构，并将持续到2041年。
这家位于艾伯塔省埃德蒙顿的公司正在与R.I. Lincoln的Pare Corp.合作。
The 2.2-mile-long, 30-ft dia. tunnel runs beneath Pawtucket and Central Falls at a depth ranging from 115 ft to 155 ft below grade. The facility will be able to store up to 58.5 million gallons of overflows, said a Stantec press statement in June. The tunnel is set to be operational in 2026 with final completion by 2027.
Initial Work
CB3A副项目经理Pete Williamson说，为了在2022年初推出隧道钻孔机（TBM），CB3A同时建造了发射轴和隧道泵站轴。
“The temporary support of excavation in soil, for both shafts, is complete and performing well,” Williamson says. The team is currently “excavating the rock portion of the [shaft] with ancillary work, including electrical and other utility feeds to support the TBM mining ongoing,” he adds.
CB3A will mine the tunnel with a Herrenknecht TBM, a dual mode machine capable of operating in both the open mode and earth pressure balance closed mode, the JV says. The rock bore diameter is 33.79 ft and final inside diameter is 30.17 ft.
During the tunnel procurement phase, CB3A proposed cost and time-saving concepts including raising the tunnel by 25 ft, tunnel liner ring design alternatives and relocation of the tunnel pump station and launch shaft, Stantec said.
威廉姆森说，复杂项目的一个重大挑战是一个密集的城市环境“是在整个隧道的2.2英里对齐中建造多个掉落轴。”威廉姆森说。“每个轴都是在不同的地面条件下建造的，并且需要严格的设计和可构造性审查，同时在当地居民和利益相关者近距离接近进步的建筑活动方面都非常重视。”
Vincent J. Mesoleslla, chairman of owner/operator Narragansett Bay Commission, notes the project as “critical” for “the next generation of Rhode Islanders ... to only ever know a clean bay and vibrant urban rivers.”
Stantec说，最终阶段工作的第一部分开始于上个月开始，预计溢流量将减少98％，并在雨水流入纳拉甘西特湾之前对待雨水。
“With the frequency and intensity of storms on the rise, the time is now for communities to take action to protect human health and the environment,” says Melissa Carter, a Stantec vice president.
In addition to challenges associated with schedule and ongoing concerns about supply chain volatility, the team seeks a solution for how it will dispose of an estimated 840,000 tons of pulverized rock material excavated during tunnel mining, she says. “There’s limited opportunity for disposal or beneficial reuse of this material,” Carter says.
Despite the challenges, the team predits the phase will be completed on time, Carter says.
Benefits of Prior Work
The region is already showing signs of progress from earlier phase work.
委员会公共事务经理杰米·萨米斯（Jamie Sammons）表示：“由于该计划的前两个阶段……我们每年看到大约85个额外的炮弹钓鱼天，并预计这条隧道有类似的好处。”“我们已经看到，上普罗维登斯河上的贝壳捕鱼场已经关闭了75年，除了更多的游泳海滩从河上游开放，除了更多的游泳海滩。我们预计第二隧道会带来类似的好处。”
Stantecand Pare have identified many cost savings measures for the project by utilizing proprietary WARi (Weighted Average Residential Index) methodology. Stantec developed its proprietary WARimethod as “a more accurate representation using 53 data point in the Census tract instead of two traditionally used by theEPA [环境保护署]确定纳税人的成本负担。”卡特说。
与反对三相方案计划始于2001年struction of a three-mile long, 26-ft-wide deep-rock tunnel under Providence to store stormwater runoff. A prior phase finished in 2015 added CSO interceptors to the Providence Tunnel, several sewer-separation projects and a wetlands storage facility.
An additional 10-ft dia. stub tunnel project is set to begin in 2031 with construction to be started in 2035, Carter notes.
