Geostructural Project Detail

Ellis Island

Location

New York Harbor

Client

HNTB Architects

Services Provided

Geostructural Design
Restoration of Historic Structure
Ground Penetrating Radar
Permits
Coastal Zone Documentation Review

Project Overview

Liberty Island’s seawall is over 6,700 feet long and was built of various construction techniques between 1913 and 1934. The seawall construction techniques included a pre-cast concrete gravity wall on cement bags, a concrete counterfort wall on timber cribbing, a concrete gravity wall on timber piles, and anchored concrete sheetpiles. Over time, the seawall showed varying degrees of deterioration. Mortar joints have eroded and large granite blocks have been dislodged and fallen into the harbor and wooden cribbing has decayed and is being attacked by marine borers -- all of which have resulted in accelerated deterioration of the seawall itself and erosion from behind the seawall compromising the seawall stability.

Schnabel teamed with HNTB Architecture to visually survey the seawall condition, and to propose rehabilitation and preservation actions. Several distress conditions ranging from aesthetic to wall stability to complete wall failure were identified through visual observation of the seawall and revetment wall. Following our visual survey, Schnabel proposed and conceptually designed rehabilitation and preservation actions, including cleaning and repointing of granite face stones, resetting granite stones, repairing or replacing broken granite inset stones, removal and replacement of deteriorated or non-matching mortar, cleaning and repairing exposed or broken seawall concrete, placement of concrete fill in cavities behind or underneath the seawall, placement of rip-rap at locations where the wall foundation is exposed, wall stabilization, and wall reconstruction.

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