Best Water/Environment: Catskill/Delaware Ultraviolet Light Disinfection Facility

As the world's largest-capacity ultraviolet (UV) disinfection plant, the $1.3-billion Catskill/Delaware facility in Valhalla, N.Y., is also the country's largest unfiltered surface water system.

The project, planned at a time when UV disinfection was used almost exclusively for residential and small commercial applications, includes 56 UV units. Each unit has a capacity of 40 million gallons a day—making it by far the largest single facility of its type, featuring the largest UV units built to date.

Designed to treat 2.2 billion gallons of water per day, the project contains a significant amount of equipment considered to be the largest and first of its kind. These include the world's largest energy-dissipating valves, which are managed by a computerized control system that balances flow throughout the facility.

One of the issues that arose during field testing involved 16 installed 84-in. knife gate valves that isolate the facility's flow control valves. Project team members discovered that the extreme amount of force being imparted on the valves during tightening of the flange bolts was distorting the valve bodies.

The team established a task force to resolve the issue, resulting in a decision to significantly modify the valves. The contractor proceeded at its own risk, prior to any final financial commitment, and completed the re-work without impacting the schedule, according to the project submitter's entry form.

Overall, the team installed more than 5,000 linear ft of 12-ft-dia steel pipe to convey water within the facility. Crews poured 121,000 cu yd of concrete and installed 1,200 tons of structural steel and 522 pieces of blast-proof architectural precast elements.

The contractor created a 4D model of the plant, which was linked to a 3D model and used to coordinate construction sequences. These helped to achieve on-time project delivery.

Best Project judges hailed the team's skill at delivering a public works project of this scope. The team "safely negotiated over 800 workers at once," said one judge. Another agreed, adding, "They overcame the challenges of those giant valves ... [and] used real-time problem solving."

The project owner, the New York City Dept. of Environmental Protection (DEP), also praised the team's handling of cost and scheduling. In a July 2013 letter commending the team, Michael Borskyowsky, DEP assistant commissioner, stated that the project team had exhibited "some of the best delivery performance metrics earned on any major DEP capital construction project." He added that the project was delivered on budget and that consent decree milestones were met.

Catskill/Delaware Ultraviolet Light Disinfection Facility, Valhalla, N.Y.

Key Players

Owner/Developer New York City Dept. of Environmental Protection

Construction Manager A joint venture of Malcolm Pirnie (now part of Arcadis) and CH2M Hill

General Contractor SEW Construction, a joint venture of Skanska USA, ECCO III and J.F. White

Lead Designer A joint venture of Hazen & Sawyer and CDM Smith

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