Nuts and Bolts (and Water) Challenge 9/11 Shrine
By ERIC LIPTON
Published: January 24, 2004
What will happen when the temperature drops so low that any traditional reflecting pool would freeze? How will people be able to take rubbings of victims' names near a waterfall that could be a messy spray? And who will be responsible for maintaining what is built and providing the money for what will certainly be an enormous annual cost?
The central design element of Mr. Arad's composition — outside of the two 200-foot-square voids that sit in the footprints of the twin towers — is a steady flow of water. Walls of water will drop into these voids from the plaza level down about 30 feet, falling into two enormous reflecting pools. The water will drop once again, falling down an additional 15 or so feet, until it nearly reaches the bedrock.
But a falling wall of water has a tendency to move laterally as a result of the vacuum it forms as it drops, said Wayne Pierce, design director at Hobbs Architectural Fountains, an Atlanta-based company that Mr. Arad has consulted on his trade center memorial plans. Combined with the wind, this could send streams or at least sprinkles of water into the underground assembly area, where crowds are supposed to gather to view the engraved list of victims' names, unless the area is properly designed.
Winter conditions would complicate this setup even further. The mist of the falling water — Mr. Pierce called it the Niagara effect — could create a thin layer of potentially dangerous ice on this walkway, which Mr. Arad wants to be open to the elements.
In Washington, the National Park Service turns off almost all of the fountains it operates in the winter months. But there are a few exceptions, including the fountains at the Franklin D. Roosevelt Memorial. Keeping the water moving helps prevent it from freezing. Yet this past week, after the recent bitter cold arrived in the region, some of the F.D.R. fountains froze, leaving the Park Service with no choice.
"We had to turn the water off," said John Parsons, associate regional director for the Park Service in Washington. "But it becomes a much different memorial then."
Various techniques are also available to try to prevent the water from freezing over in the winter, including chemical additives, special heat-producing lights or a combination of electric or gas heaters that could be installed in the reflecting pool. But each of these has its own complication, as heated water could produce a wind-blown steam or mist that might ice up, National Park Service officials said.
And then there are the leaves and the pocket change. Mr. Walker has proposed filling the plaza with deciduous trees, hardwoods that shed their leaves each fall, creating a potential hazard for the pumps that will be constantly circulating water through the fountains.
The coins, of course, come from a human source: that almost automated response among Americans when they approach any kind of fountain or reflective pool. In Washington, this repository of change draws the homeless, Mr. Parsons said, who tend to jump into the fountains late at night picking out everything but the pennies.