By Paul Fournier
AECOM/United Water design-build-operate contract with East Providence will upgrade city’s wastewater collection and treatment facilities
A massive wastewater treatment project under construction in East Providence, R.I., will help protect the quality of Narragansett Bay, New England’s largest estuary, and bring the city’s treatment facilities in compliance with a consent order issued by the state’s Department of Environmental Management (DEM).
AECOM and United Water have a $52.5-million design/build/operate contract to upgrade the city’s wastewater treatment plant and replace a pump station in Watchemocket Cove. Both facilities lie alongside the Providence River, an eight-mile-long tidal watercourse running from downtown Providence to Narragansett Bay.
Upgrades to the treatment plant, which is located in the densely populated Riverside section of southern East Providence, will address odor complaints as well as comply with a 2004 law requiring a 50-percent cut in nitrogen content in plant effluent being discharged to the Providence River and upper Narragansett Bay. Ten other facilities in Rhode Island reportedly are also working to comply with the law requiring at least a 50-percent reduction of nitrogen in treated wastewater.
Eliminating Sewage Overflows
The old pump station in Watchemocket Cove is being replaced by a 10-mgd (million-gallon-per-day) self-cleaning wet-well pump
station which is designed to eliminate untreated sanitary sewer overflows into the Providence River. Other collection system improvements include a new force main to convey sewage from the new pump station southward to the Riverside treatment plant. Originally planned for installation along Veterans Memorial Parkway and Pawtucket Avenue, the new force main was redesigned to be placed beneath the city’s East Bay Bike Path – a move that avoids traffic disruption and utility impacts on those main thoroughfares, thus saving an estimated $3 million in construction costs. Following construction, crews will restore the bike path, providing new pavement, markings and fencing.
Additional improvements consist of the construction of a 5-mgd pump station on the city’s Boyden Boulevard, and three other, smaller, package pump stations at various locations.
Sophisticated Treatment Technology
AECOM is providing design/build and construction management services for the project, according to Scott Thibault, P.E., an associate vice president for design/build at the global company’s Wakefield,
Mass., office. In addition, the company is handling planning, permitting, equipment procurement, plant start-up and personnel training. With some 45,000 employees, AECOM has clients in approximately 125 countries and had revenue of $7.7 billion during the latest fiscal year.
At the Riverside treatment facility, the AECOM/United Water team is designing and installing a biological nutrient removal (BNR) upgrade and other capital improvements including new sludge handling capability. The BNR process involves IFAS treatment technology that will enable the plant to meet and actually exceed nitrogen removal requirements of 2004 law.
Thibault explained that IFAS technology introduces thousands of tiny biofilm disk media that serve as growing platforms for biomass in
the sludge, thereby boosting the effectiveness of existing activated sludge treatment processes. Proponents of the technology say existing plants can be readily retrofitted with IFAS, substantially saving construction costs.
Thibault said the upgraded plant is designed to treat an average daily wastewater flow of 14.2 million gallons and a peak daily flow of 26 million gallons.
Plant Operation and Maintenance
United Water has the responsibility for operating and maintaining the upgraded treatment plant and sewage collection system for ten years. Under the terms of the contract, United Water operates the treatment facility while East Providence retains the authority to set rates and maintain jobs for local workers. Founded in 1869, United Water has corporate headquarters in Harrington Park, N.J., and is a subsidiary of SUEZ ENVIRONNEMENT, a world-wide company. With nearly 80,000 employees, SUEZ ENVIRONNEMENT supplies drinking water to more than 90 million people and provides wastewater treatment services for over 60 million people. The company reported sales of approximately $18.5 billion at the end of financial year 2010.
The design/build/operate contract is reportedly saving East Providence an estimated $13 million over what was budgeted to be spent under a traditional project delivery approach.
According to Thibault, the construction costs of the project are divided almost evenly between the treatment plant and the sewage
collection system. He said the three largest contracts were awarded to: Hart Engineering Corporation, headquartered in Cumberland, R.I., for installation of all mechanical processes; E.W. Audett of Providence, for electrical work; and D’Ambra Construction ofWarwick,R.I., for underground utilities.
Other major contractors are: Desperini Contracting Group of Warwick, subcontracted to Hart Engineering for forming and placing concrete; and Equality Construction Works of Greenville, R.I., subcontracted to Hart Engineering for site work.
Another subcontractor, Allied Pile Driving Inc. of Canton, Mass., drove sheetpiling for a cofferdam required for the construction of the Watchemocket Cove pump station due to poor soils in the area. Allied is also driving precast concrete foundation piles for the structure.
Treatment processes require sophisticated computerized controls, and these are provided in the
form of a Supervisory Control and Data Acquisition System (SCADA). Consultants Woodard & Curran, with offices throughout the Northeast and Georgia, has the contract to install and program the control system.
Construction at the Riverside site began in February 2011. Plant upgrades are to be finished by
September 2012, while the new Watchemocket Cove pumping station and utility work are to be complete and operational in August 2013.
As of August 2011, the entire project was about 35-percent complete and is on schedule, according to Thibault.