By Mark Haverstock

PROJECT TEAM Designer: DiGeronimo PC, Paramus, N.J. Stone supplier: North Carolina Granite Corporation, Mt. Airy, N.C. Stone installer: Millennium Stone, Tile and Masonry, Flushing, N.Y., under subcontract to contractor Kiewit Constructors

Fresh air is exactly what motorists need while traveling though the Brooklyn Battery Tunnel, which — at 9,117 feet in length — is the longest continuous underwater vehicular tunnel in North America. The Brooklyn Battery Tunnel Governors Island Ventilation Building — along with three others, two in lower Manhattan and a third near the Brooklyn portal — provide a complete air change in the tunnel every 1-1/2 minutes to help remove the carbon monoxide and other emissions created by the numerous vehicles that travel this stretch of Interstate 478.

A breath of fresh air is also what the exterior of the Governor's Island Ventilation Building needed after years of exposure to the elements. The original facade began as a glazed brick finish that did not weather well in the harsh location — over the years it disintegrated, cracked and failed. In 1975, the Metropolitan Transportation Authority (MTA) Triborough Bridge and Tunnel Authority (TBTA) decided to strip the glazed brick surface and replace it with acrylic stucco panels; however, after approximately 30 years of service, the stucco panels also failed and began falling off the facade. MTA TBTA decided that a different design approach would be required to provide a long-lasting and durable facade. It was also important that the renovations were compatible with the existing architectural concept.

Preparation of wall surface for mounting granite panels. Photograph © Suzanne DiGeronimo

MTA TBTA selected DiGeronimo PC and a team of specialty subcontractors to provide architectural and engineering services to renovate the structure. Initial tasks before the project began included a thorough investigation, document research, digital photography of existing conditions, and material for sampling and testing. This project also included underwater investigation and documentation, giving the designers a complete assessment of the current condition of the structure.

Two significant challenges were associated with the project. First, the Governor's Island Building is located on a man-made island that is largely vacant and has no direct connection to New York City. Access to the project was limited to an eight-story climb from a stairway at the midpoint of the tunnel or via water taxi or ferry from Lower Manhattan. When the 9/11 security measures were in effect, access was severely limited from both the tunnel and by water. The New York City Department of Transportation instituted restrictions on the tunnel as it had been identified as a vulnerable target. Additionally, all waterborne traffic was initially suspended and only reinstated under the supervision of the U.S. Coast Guard and the Port Authority of New York and New Jersey.

	Detail of failure of acrylic stucco panel facade. Photograph © Suzanne DiGeronimo

The second challenge for the DiGeronimo team members was to understand the nature of the previous facade failures. They needed to come up with the best solution for a successful and durable face-lift, while keeping the project on schedule through heightened security conditions.

They found the best approach was to treat the structure as a lighthouse, since it is exposed to similar marine and weather conditions that would affect the durability of the materials used on the external structure. DiGeronimo selected natural stone as the best choice for two important reasons: to match the original finish of the other tunnel ventilation buildings and to provide a durable surface with lower maintenance costs than the acrylic stucco panels or glazed brick. The design team ultimately selected Grade A Mt. Airy Granite from North Carolina Granite Corporation for its look, low maintenance and permanence.

Failure of acrylic stucco panel facade.
Photograph © Suzanne DiGeronimo

Prior to the stone installation, the DiGeronimo design called for the removal of the stucco panels and the cleaning, waterproofing and sealing of the exposed backing surfaces. To make the building's new "skin," the team designed a floating panel facade. Working with a German manufacturer, they devised a suspension system created from stainless steel and marine aluminum on which the granite panels were attached. These stone panels measure approximately three feet long, four feet wide, and 1-3/16 inches thick. This framework floats on the surface of the building, providing protection against the elements, while eliminating opportunities for weathering to occur between the panels or against the subsurface.

Though common to construction in Europe, this is the first time such a suspension system for stone panels has been implemented in a structure built in the United States.

"The result is a stone facade that acts as a shield, a first barrier in the harsh marine environment," said Louis A DiGeronimo, AIA, of DiGeronimo PC.

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