C+S June 2022 Vol. 8 Issue 6 (web)

Selection of the UV supplier and equipment was based on a rigorous specification and evaluation of both capital costs and the net present value of operating costs over the life of the system. Offering the lowest total cost of ownership and operation by using Me - dium Pressure UV technology combined with highly efficient turndown capability, the Sentinel 48 AOP UV, now known as Capital Controls® UV system with Sentinel® reactor, was selected as the advanced oxida - tion process (AOP) UV equipment.

• The ability to turn off banks of lamps and to turn down lamps to 40 percent of full power allows the system to tailor the UV power to the plant needs, thereby reducing operating costs and energy use. • The automated controls continuously adjust the lamp power to meet the target Log-destruction of NDMA. Operational Experience During a 10-day performance trial in February 2012 the system con - sistently achieved the 1-log (90 percent) NDMA removal while con - tinuously adjusting the number of operating lamps and lamp power to match varying plant operating conditions:

The system was deployed to treat the RO effluent at the advanced water treatment plant. This system includes 18 x 20 kW UV lamps to treat the peak flow of 20 MGD. The reactor is configured in a patented chevron lamp arrangement that allows banks of lamps to shut off while still achieving efficient UV treatment. The main advantages of this system are as follows: • It uses the highest power medium pressure UV lamps available. This means the system has fewer lamps, less maintenance, and a smaller footprint than alternatives.

Installing Two 20-inch Sub-Aqueous Water Mains to City Island

Dual Compound Curve Brings First-Ever NYC Technology to Long Island Sound In 2002, the City Island Bridge was determined to be in a state of seri - ous deterioration by the New York City Department of Transportation (DOT). The city proposed to replace the bridge with a state-of-the-art cable-stayed bridge on the same alignment of the old bridge, which was built in 1901. “The bridge was extremely old, and New York City had to replace it,” says Patrick Ronan, PE, a senior project manager in Dewberry’s New York City office. Next to the bridge underneath the waterway was an old, failing, and non-redundant water main. To provide a temporary



June 2022

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