World Trade Center memorial fountains a state-of-the-art design

The millions expected to visit the World Trade Center site after it partially opens later this year will see a Sept. 11 memorial that appears simple and serene: an endless stream of water cascading into two massive voids where the Twin Towers once stood.

But spitting and churning under the nearly one-acre pools will be one of the most extensive and sophisticated water-control systems of its kind.

It will pump more than 1 million gallons through a vast network of pipes that, if lined up, would run nearly the length of Manhattan. At the same time, a computer-automated system will continuously monitor and adjust the flow and condition of the falling water in response to almost any foreseeable event — even a stiff breeze.

"I won't ever see anything like this built again in my lifetime," said Jay Duddy, one of three Bergen County, N.J., plumbers who oversaw installation of about nine miles of pipes under the memorial fountains.

The automated system controlling the country's largest engineered waterfalls will keep the water's chemical balance and temperature at precisely prescribed levels. Ultrasonic sensors will trigger an increase in the volume of falling water when the wind picks up, or will shut down the fountain altogether if gusts get too strong. And a filtration system will flush out the coins, flowers, pictures or any other object visitors drop into the pools.

The state-of-the-art design highlights the lengths planners have gone to to ensure the long-awaited memorial fountains work properly — and consistently — in any conditions. But moving so much water at once and with so much precision will come at a cost to the private foundation that runs the memorial.

The electricity to keep both fountains running — estimated at one megawatt per hour — would power about 800 average homes, according to data from the U.S. Energy Information Administration. And each summer day, the pools are expected to lose about 10,000 gallons of water to evaporation — the amount in a small below-ground swimming pool.

Mostly donations

The nonprofit National September 11 Memorial & Museum Foundation estimates it will need $50 million in annual revenue to run the memorial and museum, although the memorial will benefit from a state program for reducing electricity costs. A spokesman could not say how much of the budget would be used to operate the fountains. The foundation will raise most of its annual budget through private donations but will also seek federal money, spokesman Michael Frazier said.

The fountain design symbolizes the loss suffered in the deadliest terrorist attack on U.S. soil and the impossibility of filling the resulting void, planners have said. Set to open to the public on Sept. 12, the day after the 10-year anniversary of the attacks, the memorial will initially be accessible to only 1,500 visitors at a time, as construction continues on the rest of the site. Five million visitors are expected each year, officials have said.

The project represents a unique opportunity for the three dozen plumbers — most of them from New Jersey — to take part in a historic project that also resonates emotionally.

A personal investment

One of the other three Bergen County foremen overseeing plumbing work, Jimmy Walsh of Marlboro, lost his mother in Tower One and serves as an inspiration to the other men, Duddy said.

Duddy has not taken a vacation in three years. He said long shifts have taken a toll on the families of many workers, whose secondary home has become the maze of hallways and pump rooms layered 60 feet below the memorial plaza. Duddy said he has eaten dinner in the empty pools on nights when he had to work late.

"Any other job, you can come back and do repairs and get it right," Duddy said. "Not this job. It has to be right the very first time."

While much will be made of the fountains' effect from the surface, Duddy and the other plumbers work to make sure that the invisible engine rooms below the pools perform flawlessly.

Plumbers also installed a system that collects and recycles treated rainwater from the eight-acre plaza, which is "one of the most sustainable, green plazas ever built," according to the memorial's website. It will be used to irrigate the 400 swamp white oak trees surrounding the fountains and used in the museum's bathrooms.

Mock-ups tested

Little has been left to chance.

Engineers, plumbers and architects constructed five "mock-up" waterfalls while fine-tuning the design, said Mike Russo, co-owner of 4 J's Associates, which was awarded $71 million in contracts to install plumbing in the memorial fountains and the museum. The models — set up in a Brooklyn naval yard and in Florida, among other locations — offered a preview of the decibel level of the falling water, how far it would fall from the granite walls, and the geometry of the fingerlike streams of water that flow from a weir installed around the perimeter, among other details.

"Basically, everything here is a one-off," Russo said. "No one has built a fountain this big in the U.S.," with regard to both volume of water and the height of the falls, he said.