Combined Sewerage Overflow Underground Tunnel Pump Station

Narragansett Bay Commission (Providence, RI)

Hart is proud to have played an integral role in completing Phase 1 of the largest public works project in Rhode Island’s history, on time and under budget. Hart was responsible for all construction of the underground Pump Station located over 300ft beneath the city. At a cost of $56 MM, it is one of the biggest Pump Stations ever constructed in the Northeast.

For decades, an estimated 2.2 billion gallons of untreated combined sewage and storm-water flowed annually into local rivers and Narragansett Bay. A $320 million, three-phased, multiyear Sewerage Overflow Program was launched in 2001 by the Narragansett Bay Commission to mitigate this ecologically crippling statistic.

A 16,000ft long, 230ft deep Tunnel, with a 26ft diameter was excavated to temporarily collect and store the combined sewage that had previously been overflowing directly into the bay during periods of heavy rain. Once retained underground, the combined sewage and rainwater is pumped to a nearby Wastewater Treatment Facility.

The Phase 1 Tunnel and Pump Station construction was completed in October 2008 and fully operational by November 2008. In less than a year, the belowground facility had already captured over 1 billion gallons of waste. The project’s program manager was quoted as saying, “It was just an overall success. It worked better than anyone thought it could.”

Note: The Narragansett Bay CSO project was named “Civil/Public Works Project of the Year” by New York Construction magazine in its “Best of 2009” edition, acknowledging Hart as the Pump Station Principal Contractor.


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