This site for a new residential tower is on 2nd Ave in Manhattan, at a low elevation that is within the flood zone. The foundation design consists of a series of caissons drilled to the depth of bedrock (most likely). This foundation approach avoids creating a basement that would be exposed to flooding.
In this view we see the rig drilling a new caisson pier, with the drill inside the steel casing. The rig pushes the casing down as the drill proceeds to temporarily hold the walls of the excavation from collapsing.Ā This pier is tight to the party wall of the adjacent building. With a series of caissons along this party wall, it is likely that underpinning can be avoided.
An earlier site view below shows the drill as it is aligned with another casing.
