Yonkers Contracting Co., Inc.

Scope Of Work

The largest wastewater treatment plant upgrade performed in Westchester County has recently been completed by Yonkers Contracting Company under two contracts. Working within a site constrained by the Long Island Sound and neighboring properties, Yonkers improved the sea wall by providing an alternate design that addressed constructability and long-term reliability.

The first contract involves installation of plant improvements and expansion to increase capacity from 13.6 million gallons per day (mgd) to 20mgd by rehabilitating or replacing every process of the existing facility. Work included structural and architectural improvements, installation of a high efficiency oxygenation system, and installation of a new SCADA system to monitor and control the entire plant.

Yonkers designed and implemented a temporary bypass system to keep the plant in continuous operation while the improvements were made. The automated system, installed within the existing plant, met maximum flow requirements of 56 mgd.

BNR filtration facilities were constructed under the second contract that diverts effluent to a new Biological Nutrient Removal (BNR) building and a new Ultra Violet (UV) Disinfection building. These tertiary treatments are designed to remove harmful nitrogen and kill bacteria from the effluent without using chlorine. Other work included the construction of chemical buildings, storage tanks, process controls, new pump systems, large valves and pipe.