Projo 7 to 7 News Blog

By Peter Lord
Journal environment writer

Today's rainstorm provided the perfect test for the Rhode Island's new $359 million combined sewer overflow project. By 2:45 p.m., 1.57 inches of rain had fallen, sending 61.5 million gallons of sewage and street runoff into the giant tunnel completed just this month under downtown Providence.

As per design when the tunnel reaches capacity minus 20 minutes, seven big gates closed automatically and sealed the tunnel shut. Sometime after the storm, the captured storm runoff and sewage will be pumped up to the Fields Point sewage plant for treatment.

After the gates closed, additional runoff began being diverted into the sewer plant's wet weather tanks, which have additional capacity of 123 million gallons. Sewage in those tanks will get primary treatment and disinfection.

During the course of the day today, engineers for the Narragansett Bay Commission practiced closing the gates to the tunnel at 60 percent capacity, and then 80 percent capacity -- exercises they had planned to undertake during separate storms.

Everthing worked fine, according to commission spokesperson Jamie Samons. Commission engineers were very excited to see the new equipment do its job. And a day of polluted overflows was diverted from Narragansett Bay.

Video: With phase I complete, we take a tour of the combined sewage overflow project far below the streets of Providence.

 Tags  CSO Providence

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