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System Overview

The Pawtucket Water Supply Board (PWSB) is a water supplier that serves a population of over 100,000. The retail service area includes the Cities of Pawtucket and Central Falls and the Valley Falls section of the Town of Cumberland. The PWSB owns and operates the water systems in Pawtucket and Valley Falls, and the City of Central Falls.

The water resources of the PWSB consist of both surface water and groundwater within the Abbott Run watershed, a tributary of the Blackstone River. The watershed lies within the Town of Cumberland in Rhode Island and the Towns of Wrentham, Plainville and Attleboro in Massachusetts. The PWSB owns about 10% of the Abbott Run watershed.

The PWSB has decommissioned its 1938 water treatment facility in Cumberland and has been producing potable water at its new state-of-the-art treatment facility since March 19, 2008.

The new treatment facility includes a new raw water pump station capable of pumping 26 million gallons per day (mg/d) through eight (8) Johnson intake screens. The raw water pump station and the treatment facility have standby power that will support 100% of their loads.

The treatment plant has 4 up-flow clarifiers that will operate at 4,000 gallons per minute (gpm), and 8 filters that operate at 2,000 gpm. The facility is capable of producing up to 25 mg/d. The water treatment processes are (in order): up-flow clarifiers, deep bed granulated/activated carbon filters (6 feet), and ultra-violet (UV) disinfection. Finished water is stored in two tanks: 1.4 mg and 5 mg. The facility has 4 high-lift pumps capable of pumping up to 35 mg/d to the distribution system. All finished water entering the distribution system gets treated with hypochlorite (chlorine), hydrated lime (PH control), fluoride, and orthophosphate (a corrosion inhibitor).  Click here if you're interested in reading about orthophosphate (a link to a FAQ page written by the people who supply water to the City of Arlington, VA.)

After treatment, water leaves the pump stations through a network of 12, 16, 20, 24 and 36 inch diameter water transmission mains to all parts of the PWSB system, much like the spokes on a wheel. Smaller distribution mains distribute the water to all areas of the PWSB system. In all, there are approximately 240 miles of transmission and distribution water mains in the PWSB system.

The pipelines installed before 1958 are constructed of unlined cast iron. Pipe lined with cement was not manufactured until after 1958. These unprotected older mains are subject to rusting on the inner surface, resulting in rust particles settling to the bottom of the main and causing discolored water when the flow of water is disturbed. The PWSB has accelerated the program of renovating these older mains by cleaning them to bare metal and applying a cement coating to prevent further rust problems. Mains older than 1920 and all mains less than 6" are being replaced. Over 100 miles of main renovation and replacements have been completed, with approximately 100 miles of main scheduled for renovation by 2012 to complete the system.

There are a number of appurtenances within the distribution system. The system has approximately 1700 fire hydrants and 6,000 line valves. These are replaced as needed with the main renovation program.

The distribution storage facility of the PWSB is comprised of two storage tanks. Earth Tech will be adding 5 million gallons of additional storage at the new water treatment plant. The two tanks on the west side of the system are connected to the transmission and distribution grid through two 24 inch diameter water lines. The original storage structure at this location was constructed in the 1870s as an open air 22 million gallon reservoir and was replaced with a 10 million gallon tank in 1994.

There are approximately 22,200 customer service connections in the PWSB distribution system.  Each service connection has a service line, curb stop and meter. In the PWSB system, the PWSB owns and is responsible for the repair and replacement of the portion of the service line within the public right of way, generally up to and including the curb stop. (The PWSB has partnered with Aquarion Corporation to provide the option of a customer protection plan for the portion of the service owned by the customer.)  The PWSB owns all of the water meters which are two inches or smaller.

The PWSB has a staff of 53 employees that perform all of the operations and maintenance for the organization. The PWSB owns and operates its own fleet of vehicles.

The PWSB has a Board of Directors and is a semi-autonomous extension of the City of Pawtucket. It is an enterprise fund agency; no subsidization exists between the City and the PWSB. Rates are determined by the PWSB Board and are subject to the approval of the RI Public Utilities Commission (PUC) after a thorough examination and review by the Division of the PUC and the State Attorney General's office which acts as an advocate for the rate payer. The PUC has approved rates for pay-as-you-go funds for capital projects, and for debt service for the financing of the major capital projects.

Financing for the water treatment facilities and the water main projects is obtained through the State of Rhode Island Clean Water Finance Agency. The agency provides subsidized funding through the federal State Revolving Fund Loan Program (SRF) for drinking water. The SRF is administered through the State Department of Health.

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