September 13, 2011 ·

Landscape architecture brings majesty, rebirth to 9/11 memorial site

“We’re sometimes dismissed as the guys who put the trees in,” says David Walker about his firm’s seminal role in the design of the 9/11 memorial site. The 50-year-old Walker, who co-led the project for Peter Walker & Partners, his father’s renowned landscape architecture firm, is in equal measure self-effacing and self-assured, both traits that served him well throughout the seven-year odyssey that lead to this week’s opening of the site. Moreover, he is also part of what, by all appearances, is an extraordinary design accomplishment.

Walker’s design, a stately and ever-evolving grove of majestic oak trees, is coupled with architect Michael Arad’s deeply symbolic but severe memorial pools. This design pairing and the inherent tension between life and death, historic memorial, and future renewal at the heart of it will likely be seen as the foundation of the success of this challenging and exceedingly high-profile site.

A rendering of Peter Walker & Partners’ design for the 9/11 memorial site. Rendering by Squared Design Lab, Courtesy of PWP Landscape Architecture.

The Walker concept was a simple one: “We said that you need a forest to represent renewal,” David Walker says. “The basic notion is that of a forest in downtown Manhattan to communicate rebirth.” The “forest” evolved into the now largely complete installation of 400 swamp white oak trees and over 40,000 tons of new soil on the 7-acre memorial site and surrounding streets. In effect, the Walkers brought ground back to ground zero.

The layout of the trees themselves is at once cultivated and naturalistic, formal and organic. Viewed east-to-west, the oaks are arrayed along a tightly defined grid punctuated by granite slabs to create a boulevard feel. Viewed north-to-south, however, the planting is randomly placed, as in a natural forest. The oaks, cultivated in a New Jersey nursery for the past four years, are now 25-feet tall and pruned to enhance their 15-foot high canopies. Over time, the trees are expected to reach 65 to 75 feet, with their soaring canopies growing together to create “a cathedral-like appearance” when viewed east-west and a fulsome forest from the north and south. Approached from either direction, the site channels visitors through an urban forest to the solemn reflecting pools at its center. “The species of tree we chose creates a vaulted ceiling structure, evoking a religious architectural feel,” Walker explains. The effect also evokes the archways or tridents of the first three stories of the fallen World Trade towers themselves. As the trees mature, the archways will rise once more.

Walker has little to say of the well-publicized head-butting and conflicts of personalities that surrounded the project. “It was an ego-driven process by everyone involved,” he admits, although one detects little of his own. “But it was all driven by a desire to create a lasting statement, and the net result is a design that will endure.”

And in one last study in contrasts, David Walker makes clear that part of the core concept of the memorial is that it actually becomes less of a memorial over time. “There was a lot of discussion about the fact that this will always remain a memorial, but as 9/11 fades beyond living memory, it will serve increasingly as an urban park more so than a memorial,” Walker predicts. “It may feel less like a grave site over time and more like a living, growing park. This is how we thought about it from the very beginning.”