The Combined Sewer Overflow Phase IIIA Facilities project is the third phase of projects to contain the combined sewer overflows during rain events so that the stored flows can be returned to the wastewater system for treatment after storms. During heavy rain storms, these combined flows frequently exceed the capacity of the sewer system and overflow into local rivers and Narragansett Bay. These overflows carry pollutants in the form of sewage solids, metals, oil, grease and bacteria which can affect the health of those who swim in polluted water or eat shellfish contaminated by these materials. The Phase III Facilities include a long deep rock tunnel, two work shafts, four drop shafts, a tunnel pump station, and several improvements to the wastewater collection system.
- Protect the water quality in Narragansett Bay, contributing to reducing annual combined sewer overflow volumes by 98 percent.
- Achieve an 80-percent reduction in shellfish bed enclosures.
- Supports reaching compliance with Narragansett Bay Commission’s Consent Agreement with the Rhode Island Department of Environmental Management.
- Saves Narrangsett Bay Commission’s ratepayers $99.6 million financing the project with WIFIA loans compared to a bond issuances.