By TIM FAULKNER/ecoRI News staff
PROVIDENCE — This month's rain hasn't yet stopped, but Greater Providence has already swallowed an ocean of stormwater.
A June 7 storm dropped 3.2 inches of rain and filled up the 66 million-gallon overflow tunnel running under the city that delivers stormwater to a wastewater treatment facility on the waterfront. Additional overflow was sent to holding tanks in Providence and East Providence. An unspecified volume of stormwater was dumped directly into Narragansett Bay, as the tunnel exceeded its capacity, which is equipped for a 3-month storm, or about 1.6 inches of rain every six hours.
Monday’s rainfall was heavy, too. In 24 hours, 31.7 million gallons of stormwater flooded the tunnel. An additional 86.9 million gallons went to the Field’s Point treatment plant. On an average dry day, Field's Point treats 40-50 million gallons of wastewater, with a capacity of 77 million. During heavy rains, all collected stormwater and sewage receives some sort of treatment and disinfection. However, all of the initial, most polluted stormwater, receives full processing before it flows into the bay.
The Narragansett Bay Commission's Combined Sewer Overflow (CSO) project is in its second phase and currently processes about 60 percent of the stormwater and wastewater from Providence, Pawtucket and Central Falls.
Work on the Hope Street and North Main Street areas are expected to finish in early August. Work along the Woonasquatucket River Greenway Bike Path is nearly done and the bike path is scheduled to reopen June 14. A pipe is also being installed between Gano Street and Richmond Square on the East Side.
The project has already created a cleaner and healthier Narragansett Bay by reducing the amount of sewage released into the upper bay. Shellfishing areas, beaches and other habitats have shown significant improvement.