Waste Water Treatment Facility

The WSA owns and maintains a 7.7 million gallon per day (MGD) advanced wastewater treatment facility which discharges into the Pawtuxet River, a major tributary to Narragansett Bay. The original facility was constructed in 1965 as a secondary treatment facility that could provide treatment for an average daily flow of 5.2 MGD and a peak flow of 15.6 MGD. Since 1965 the facility has undergone several upgrades and minor modifications.

New environmental concerns and RIPDES Permit levels for nitrogen and phosphorous required the WSA to initiate planning of new facilities to address these concerns and mandates. This $35 million construction project was completed in September 2004. The upgraded facility is now capable of reducing nitrogen and phosphorous pollution to acceptable levels in addition to continuing to treat conventional pollutants such as biochemical oxygen demand, suspended solids and fecal coliform. In addition, disinfection of the effluent from the facility is now done by sodium hypochloride and chlorine toxicity is eliminated through a dechlorination process using sodium bisulfite. During the first year of operation starting in November 2004, the facility has achieved complete compliance with its new stringent limits.

The WSA owns and maintains 45 wastewater pump stations. Except for a small portion of the western part of Warwick, the public sewerage system is tributary to the Warwick Wastewater Treatment Facility. Sewer service is also available to the western sections of the City through the terms of an intermunicipal agreement between Warwick and the Town of West Warwick. Most of the connections in Warwick to the West Warwick regional wastewater treatment facility have occurred through individual private agreements with the Town of West Warwick and with the approval of the WSA. The West Warwick Agreement establishes a reserve capacity at that facility. Most of the 291,000 gallons per day for the City of Warwick remains available at this time. The WSA also pays the Town of West Warwick a flow based proportion (2.41%) for the capital costs incurred for the upgrades to the West Warwick facility.

Due to the ongoing sewer construction program and new connections to the expanding sewer system, the number of persons served by the system continues to grow. At present, there are approximately 17,700 customer accounts. These accounts are divided into classes: Residential and Commercial. There has been a 24.82% increase in the number of customer accounts in the last four years. Residential billable water consumption has increased by about 26% over this time while Commercial users’ consumption has increased by only 18%. This large increase in residential usage reflects the type of geographic areas into which the sewer system continues to expand. This increase is projected to continue to increase at a rate of 1,200 – 1,600 new connections/users per year.

As noted, the discharges from the WSA treatment facility as well as certain WSA programs and activities are governed by a RIPDES permit issued by RIDEM. One program, the WSA Pretreatment Program is both mandated and regulated by the RIDEM and the U.S. Environmental Protection Agency while, at the same time, is a regulatory program implemented and managed by the WSA. This program regulates the discharges into the WSA sewerage system through a system of discharge permits for regulated sewer users. The prime purpose of the program is to eliminate and/or control toxic and incompatible wastewater discharges to the sewer system and protect the sewer collection system, the treatment facility, WSA staff, the public, the Pawtuxet River and Narragansett Bay.