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North Dorchester Bay CSO Tunnel South Boston, Massachusetts Barletta was a joint venture partner on the Massachusetts Water Resources Authority’s $150 million CSO Storage Tunnel project. The North Dorchester Bay CSO Tunnel is designed to temporarily hold up to 19 million gallons of combined sewer and storm water overflows caused by heavy rainfall. For decades, combined sewer overflows have discharged at six outfalls along South Boston’s public beaches. This project eliminates CSOs to the Bay, protecting swimming beaches, shell fish beds and other sensitive waters. A 350 ton custom-built tunnel boring machine drilled and lined a two mile long, 20 foot diameter tunnel through glacial outwash sands and Boston Blue Clay at depths of 30 to 50 feet below K Street, Columbia Road, Day Boulevard, and the M Street, L Street, and Carson public beaches in South Boston. The machine was lowered into place through a 55-foot-deep, 50-foot-diameter mining shaft at the starting point alongside the Massachusetts Port Authority’s Conley Container Terminal near Castle Island. It was removed through a 40-foot-deep, 34-foot-diameter receiving shaft drilled at the end point of the tunnel, behind the Massachusetts State Police barracks. The TBM typically traveled 88 feet a day, and completed the tunnel 5 months ahead of schedule. An average of 25 people worked underground and 30 people above ground at any given point during the construction. |
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