With its grove of trees, the Memorial’s plaza is an actual green roof for the structure housing the 9/11 Memorial Museum, a train station and other facilities 70 feet below street level. Landscape architecture firm Peter Walker and Partners designed the plaza and a “suspended paving system” to support the swamp white oak trees growing on the plaza.
The paving of the plaza sits on a series of concrete tables that suspend the plaza over troughs of nutrient-rich soil for the planted trees. The system’s design allows for stable pavement on which people can walk, while providing a space for uncompacted, or loose soil, for healthy tree growth. Many times urban trees live in stressful conditions because they are planted underneath pavements with compacted soil, potentially choking off the nutrient and water supply to roots.