Gannett Fleming Project Recognized by ACEC New York
May 25, 2010
 (Locust Valley, N.Y.) The American Council of Engineering Companies of New York (ACEC New York) selected Gannett Fleming’s Grass Island Wastewater Treatment Plant’s (WWTP’s) ultraviolet (UV) disinfection system project as a Silver Award Winner in the Water and Wastewater category in its 2010 Engineering Excellence Awards Program. The ACEC New York Engineering Excellence Awards Program recognizes engineering firms for projects that demonstrate a high degree of innovation, achievement, and value.
An innovative design and a carefully planned construction staging schedule enabled the town of Greenwich, Conn., to improve its Grass Island WWTP disinfection system without interrupting daily operations. Utilizing UV disinfection, the project improved the water quality of the nearby Long Island Sound by eliminating the toxicity impacts associated with chlorine.
The town of Greenwich retained Gannett Fleming to prepare a disinfection feasibility study and provide design and construction management services for a new disinfection system to satisfy the National Pollution Discharge Elimination System (NPDES) permit issued by the Connecticut Department of Environmental Protection (CTDEP). The permit contains stringent residual chlorine limits requiring a total reduction in total residual chlorine (TRC) prior to discharge to the Long Island Sound.
The Grass Island WWTP is located in a residential area of Greenwich, a town of more than 62,000 residents. Adjacent to a boatyard and public walking trails within an environmental preservation area, the plant required improvements to its wastewater disinfection system to satisfy the new NPDES permit. To meet the stringent residual chlorine limits and to minimize project costs by utilizing the existing infrastructure, multiple alternatives were evaluated, including chlorination /dechlorination systems and UV disinfection systems.
UV disinfection was the most cost-effective alternative since the existing chlorine contact tanks could be modified to accommodate UV equipment and lower operations and maintenance costs throughout a 20-year operating period. The elimination of a chlorine-based disinfection system improved the water quality of the Long Island Sound by eliminating the toxicity impacts associated with chlorine. A safer working environment was also created since the requirement to handle and store chlorine, a hazardous chemical, was eliminated.
For more information, please contact Judy L. Hricak at (717) 763-7211, ext. 2624 or via e-mail.
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