News & Publications

(NEW YORK, NY – April 15, 2011) – The American Council of Engineering Companies – New York has bestowed the 2011 Gold Award on the new City of Peekskill (NY) Water Treatment Plant.

To meet its treatment, and supply goals, the City of Peekskill hired the Hazen and Sawyer to perform a technology evaluation and pilot study to determine the best treatment process for the new plant. Dissolved air flotation (DAF) was confirmed as the optimum technology for treating the City of Peekskill’s water supply.

In conducting its pilot study, the entrant assessed two types of DAF processes – conventional DAF treatment, and a relatively new, proprietary high-rate DAF technology– each followed by filtration. Pilot data confirmed that both processes efficiently provided high-quality finished water with low turbidity and high particle removal, while maintaining adequate filter run lengths. For further analysis, the entrant utilized Computational Fluid Dynamics (CFD) modeling to optimize the conventional DAF plant design, and prepared cost estimates for each DAF process. Based on detailed economic and non-economic comparisons of the two processes, conventional DAF was found to be more advantageous and was implemented by the entrant in the Peekskill WTP’s design.

The new Peekskill WTP demonstrates the Hazen and Sawyer’s dexterity in customizing design features and technologies to address site challenges. This aptitude for problem-solving has resulted in a treatment plant with a number of key advantages, including:

• Innovative application of technology. Conventional DAF technology was applied in a highly innovative manner in designing the new Peekskill WTP. Customized innovations included utilizing CFD to optimize facility design and minimize both plant footprint and depth/extent of rock excavation. The result is a plant with a compact, efficient layout.

• Design benefiting public health and environmental safety. The existing plant was inconsistent in meeting Disinfection By-Product (DBP) regulations. DBPs are known carcinogens that can affect public health. The new plant addresses this issue by using the DAF process to minimize their formation, through the removal of organics. Also, the plant uses non-toxic carbon dioxide rather than hazardous acids to lower pH levels, thus enhancing organics removal while ensuring operational safety for plant personnel.

• Handling complex issues with ease. The new Peekskill WTP faced several complexities, including the connection of the new facility and high-service pumps to the existing clearwell without interrupting service; intake installation; and a project site underlain with bedrock, requiring costly excavation. The entrant employed a successful strategic approach through optimization of the conventional DAF process, and inclusion of a pump station that allowed the plant to be constructed at grade, minimizing excavation.

Since our founding in 1951, Hazen and Sawyer has focused on two things: providing safe drinking water and controlling water pollution. Our range of services encompasses the planning, design, and construction management of water and wastewater-related projects – from clean water treatment, storage, and distribution to wastewater and stormwater collection, treatment, and reuse.