Narragansett Bay Commission Combined Sewer Overflow, Phase I
Location: Providence, Rhode Island
Owner: Narragansett Bay Commission
Market: Wastewater
Construction Cost: $250 Million (Approximate)
Construction Start/End: 1999/2009
Jacobs Associates’ Role: Construction Management for Shafts and Tunnels in Joint Venture with Gilbane Building Company
The Narragansett Bay Commission’s (NBC) comprehensive Combined Sewer Overflow (CSO) Project will dramatically reduce the discharge of sewer and rain water overflows that would otherwise enter the bay and its tributaries untreated. The initial Phase I will collect and transfer up to 64 million gallons of combined sewage into a deep storage tunnel for pumping and treatment.
The centerpiece of this project, the 30-foot excavated diameter Main Spine Tunnel extends some 3 miles in length about 250 feet underground. The excavation through sedimentary rock formations via hard-rock tunnel boring machine (TBM). Initial support measures for the Main Spine Tunnel called for installing around 16,000 concrete segments, each weighing 12,000 pounds.
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