New York City Harbor: A new face for a national landmark

One of our nation's great historical landmarks, Ellis Island, lies in New York Harbor beside Lady Liberty. The largely man-made island is bounded by over 2000 meters of seawall that has been subjected to the elements for 80 to 100 years. The walls have experienced varying degrees of degradation, including loss of structural stability, discoloration and damage to the granite facing blocks, erosion of mortar joints, and dislodged or missing blocks on the wall face. The Statue of Liberty Island National Monument and the National Park Service undertook a significant remediation effort for the seawalls spanning from August 2006 to July 2008. It included a large number of restoration and retrofit techniques ranging from repointing of granite blocks, to significant structural underpinning and lateral support of the seawall using modern geo-technologies such as micropiles and grouting. The types of repair were carefully chosen to preserve the historical fabric of the seawall. The mortar and new granite blocks were color-matched to ensure historical accuracy and blending with current conditions. Micropiles were chosen for structural repair because they are low-impact, drilled elements that were installed from the land side of the island and did not require work from the water or special permits. This paper describes the repairs that were performed and the unique challenges faced when uncovering the true wall conditions during construction. Copyright 2010 ASCE.