This project (contract 115619) composed five distinct portions at the World Trade Center site which all ran simultaneously.

The first portion involved the suspension of the 1 & 9 subway tunnel, which required the joint venture to install over 450 micropiles to support the structure.

The second portion of the project required the installation of tiebacks to reinforce the east bathtub slurry wall utilizing low headroom drilling equipment.  This work took place in difficult confined working conditions as numerous contractors were working in surrounding areas installing slurry wall panels, performing mass excavation, and demolishing existing structures.

In an effort to accelerate the completion of the excavation of the tower 3 and 4 footprints, the third portion of the project involved the installation of tiebacks into a temporary secant wall along the 1 & 9 tunnel.  This work was performed during double shifts and weekend hours and was completed in two and a half months.

The fourth portion encompassed the installation of adjacent jet grout columns inside and outside the 1 & 9 tunnel as well as the installation of low headroom minipiles.  This work was performed in order to provide a water cut-off beneath the footprint of the 1 & 9 tunnel at the north and south ends of the east bathtub.

The fifth portion of the project required the installation of low headroom micropiles in order to provide lateral stability to the installed jet grout mass and to support cast-in-place wall segments which were installed by another contractor beneath the 1 & 9 tunnel.  The joint venture was then responsible for installing tiebacks into these cast-in-place wall segments.