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Village of Northport Wastewater Treatment Plant Phase II Upgrades

Plant upgrades dramatically reduce nitrogen in the effluent and help foster a sustaining environment in the Sound.
  • An aerial view of the Village of Northport-Gannett Fleming.

    Waters in the Northport Harbor flow into the Long Island Sound, an estuary of national significance.

  • An exterior view of the Village of Northport Wastewater Treatment Plant-Gannett Fleming.

    The Village of Northport made significant upgrades to its Wastewater Treatment Plant.

  • An exterior view of the denitrification building-Gannett Fleming.

    The denitrification facility is the heart of the project.

  • An interior view of the denitrification building shows an extensive network of treatment equipment-Gannett Fleming.

    The denitrification system blends seamlessly with the existing infrastructure.

  • A view of special metering pumps that regulate the amount of methanol infused into the denitrification system-Gannett Fleming.

    Chemical metering pumps precisely regulate the amount of methanol infused into the denitrification system.

Village of Northport, New York

Chu & Gassman Consulting Engineers, PC

Village of Northport, New York

Our Role
Planning, Design, Consulting, Construction Assistance.

0.45 mgd
Construction Cost
$5 million
1 year 6 months
  • Nitrogen discharge reduced from 21 pounds per day to 6.6 pounds per day
  • Compliance with the LISS permit limits were achieved, and a $37,500-per-day fine avoided
  • Centerport Beach reopened after being closed for five years due to poor water quality
  • Septic Offset Program developed to credit the Village for septic to sewer conversions.

The Long Island Sound is a major source of food and recreation for more than 8 million people that live along its coast in New York and Connecticut. In 1985, the Environmental Protection Agency (EPA) and the states of New York and Connecticut joined to form the Long Island Sound Study (LISS), dedicated to restoring the health of this vital waterbody. 

The partnership produced a Comprehensive Conservation and Management Plan, which identified an over-abundance of nitrogen as the primary long-term threat to the ecosystem.  The Village of Northport Wastewater Treatment Plant (WWTP), located in Northport, New York, was one of the many WWTPs affected by new permit limits as a result.

What We Did

Gannett Fleming evaluated different treatment processes and prepared a detailed Engineering Report for approval by state regulatory and funding agencies. With the state’s approval, the firm provided design and construction oversight services for biological nutrient removal improvements, including a deep-bed sand denitrification filter system, methanol supply system, and an innovative magnesium hydroxide pH control system. The pH system maintains a minimum pH level necessary to support the growth and performance of nitrifying bacteria essential for the removal of nitrogen in the wastewater. Typically, the industry standard for pH control in WWTPs is sodium hydroxide, a dangerous chemical that can cause chemical burns and blindness. By comparison, magnesium hydroxide is safer to handle, more effective on a pound-for-pound basis, less expensive, and extremely dose-tolerant.  

Under the new LISS permit requirements, the Northport WWTP needed to reduce its nitrogen discharge from 21 pounds to 10 pounds per day. The new system was delivered under budget and with superior results, with an average total nitrogen discharge of only 6.6 pounds per day. This leaves open the possibility of future connections to the Village’s sewer system.

Key Features

  • Deep-bed sand denitrification and filtration system and associated methanol supply system to provide for the growth of nitrogen-consuming bacteria
  • Magnesium hydroxide pH control system to ensure reliable denitrification during colder winter months
  • Screen and compactor system to reduce re-ragging
  • Six-section motor control center with normal and emergency busses and variable frequency drives for process equipment
  • Process management and control system upgrades that enable plant operation from a remote location.

Sustainability Features & Outcomes

  • Daily nitrogen discharge into the Long Island Sound reduced by 69 percent
  • Smart design yielded an energy savings of 35 percent versus traditional approaches, as audited by the New York State Energy Research and Development Authority
  • Magnesium hydroxide-based pH control system is safer for the environment than the traditional sodium hydroxide system.

Awards & Recognition

  • Platinum Award, 2016, American Council of Engineering Companies of New York, Engineering Excellence Awards.

Similar Projects: Architecture, Facilities: Civil/Site Development, Engineering, Geotechnical: Foundations, Environmental Management & Remediation: Permitting, Geotechnical: Site Evaluation, Facilities: Structural, Wastewater: Wastewater Treatment Plants, Water/Wastewater, Engineering: Water/Wastewater