Newtown Creek Water Pollution Control Plant Expansion and Upgrade, New York, NY, USA

The largest of the 14 wastewater treatment plants in New York City, Newtown Creek is currently undergoing a major expansion and upgrade intended to increase its capacity by 50% and extend secondary treatment to all its inflow, ahead of a 2007 deadline.

In August 2003, a joint venture of Slattery Skanska, Picone/McCullagh JV and Perini Corp. began work on the upgrade, which will ultimately expand the plant's capacity to a daily 1.8 million m³ and increase the number of treatment areas from 16 to 24.

The project will involve the construction of a series of new grit, aeration and sedimentation tanks together with the remodeling of the existing aeration and sedimentation facilities. New control and administration buildings will also be built along with piers to support air main and odor control piping. Modifications will have to be made to a number of pre-existing elements and extensive integration of old and new plant components undertaken.

This contract, valued at $493 million, is one of many that have been awarded as part of a massive 13-year program, costing an estimated $2.2 billion, to enable Newtown Creek to achieve compliance with the requirements mandated by the federal Clean Water Act. While the plant construction work is scheduled for completion in January 2008, the last elements of the wider project are not expected to be finished before 2013. The 53-acre facility will be the last of the city's treatment plants to be upgraded to meet federal standards.

BACKGROUND

Located in the Greenpoint area of Brooklyn, the original plant was built in1967 and stands on the heavily industrialized shore of the channel separating Greenpoint from Long Island City, Queens. Historically, wastewater treatment has used a high-rate activated sludge process without primary sedimentation, which removes around 65% BOD5 and 75% TSS.

The secondary treatment requirements of the Clean Water Act require 85% removal and a number of options were considered to upgrade the plant to achieve this.

One suggestion required demolishing most of the existing facilities, constructing new primary tanks and implementing a new step-feed biological nitrogen removal activated sludge process. A second proposal would have essentially preserved the existing activated sludge process, adding a subsequent biological filtration step to remove the additional TSS, BOD5 and nitrogen. However, an evaluation study undertaken showed that by simply converting the existing aeration tanks to step-feed operation, TSS and BOD removals could be significantly improved. Although it provided no additional nitrogen removal, this course of action, with the addition of extended step-feed aeration/sedimentation capacity, would successfully meet secondary treatment requirements, and at a lower cost than the alternatives.

Designed to provide treatment for an annual average flow of 1.2 million m³/d and a peak of 2.6 million m³/d in wet weather, this approach also helps to overcome the major problem posed by a lack of treatment capacity when storm water swells the inflow. It has been estimated that this had previously led to the release of around 30 million m³/y of raw effluent from sewer overflows.

WATEWATER TREATMENT PLANT UPGRADE AND EXPANSION

Four aeration tanks and four sedimentation tanks at the Central Battery area of the plant are to be demolished and rebuilt, while a series of modifications will be made to eight aeration and eight sedimentation tanks in the South Battery area. New foundations and support piers will be built at both locations. A new North Battery will be constructed, comprising new grit and aeration tanks and associated sedimentation tanks. These tanks will extend over an area of around 28,000m² and require over 60,000m³ of concrete for their construction.

In addition, a new influent feed system will also be installed requiring 30m of encased piping and a 3,600m² control building built to service the new and modified tanks. Eight new process air blowers will be procured and installed in the existing main building and a program of associated utility work, including an extensive electrical system upgrade, undertaken.

Associated with the work at the plant itself, the Manhattan Pump Station, which conveys the combined sewage flow from Manhattan to the plant will also require to be significantly upgraded and enlarged.

With a rated capacity of 1.2 million m³/d, this is New York City's largest wastewater pump station and serves an area of 4,162 acres of land, fed by 180 miles of sewers. The upgrade program involves increasing the station's capacity to 1.5 million m³/d and increasing the static lift necessary to match the higher hydraulic profile of the upgraded Newtown Creek plant. This part of the project will require an associated upgrade of the electrical supply and internal power distribution system together with extensive pipe and valve modifications and the installation of a new state-of-the-art odor control system.

A number of other works are planned to round off the whole revamping of the plant, including an education center, public amenity walk and a variety of specially commissioned artworks have been suggested to augment the site. The architectural design of the plant has been carefully considered so as to mitigate the impact of the plant within its setting. Some of these design elements have already received Excellence in Design Awards from the New York City Art Commission for their aesthetic appropriateness on City-owned property.

KEY PLAYERS

New York City Department of Environmental Protection is the project sponsor. The main contractor in the plant expansion program is a joint venture of Skanska USA Civil Picone/McCullagh JV and Perini Corp, with ownership in the ratio 45:30:25, respectively. The individual Skanska companies involved are Slattery Skanska, Gottlieb Skanska and Underpinning & Foundation Skanska. Hazen and Sawyer led the project planning and design team which included Greeley & Hansen and Malcolm Pirnie. The Polshek Partnership were the architects for the disinfection and administration buildings. The environmental impact studies were performed by AKRF. Sanitaire are suppliers of aeration equipment and Bird Machine Company are supplying centrifuges.