Battening Down the WTC Hatches

By Abigail Goldring, Media Relations Staff

When Superstorm Sandy hit New York City on October 29, 2012, much of the World Trade Center site was still under construction, including the “South Bathtub” where Liberty Park and the Vehicular Security Center (VSC) – the entrance for WTC delivery vehicles and parking — now stand.

Water driven by Sandy’s storm surge came rushing in, gushing downhill towards the site and straight into the cavities created from ongoing rebuilding efforts.

As the seventh anniversary of the devastating storm approaches, the WTC campus today is not only home to office buildings, businesses, and critical transportation networks, but to a modern and advanced flood mitigation system set to fully protect the site and transportation infrastructure from another storm like Sandy.


An at-grade sliding flexible barrier at the Memorial sidewalk

Carla Bonacci, the Port Authority’s assistant director for WTC Infrastructure and Project Development, led a team of project managers, designers, and contractors to develop the unique flood mitigation system, called the Water Intrusion Protection System (WIPS).

Today, a flood wall around the site’s perimeter can be deployed and more than 200 individual barriers are in place. The completion of the remaining few installations is set for early 2020. Additionally, interim measures are already in place for the Performing Arts Center site currently under construction. As construction progresses, permanent flood protections will be concurrently built there.

“Sandy impacted us significantly during construction as well as disrupting PATH service, but the stakes are even greater now with an operating site and thousands of daily workers,” Bonacci said. “With the completion of the WIPS World Trade Center resiliency program that we began designing in 2013, we’ll be addressing the risks of climate change and ensure the long-term safety and security of the area.”


Bonacci on the WTC site

The intricate system includes three custom-designed rings of protection that blend in with the existing site and accommodate the site’s unique topography and history. In fact, much of the equipment used has not been configured in this way anywhere else in the country.

The first ring of protection is an innovative bollard protection system (BPS), which utilizes the sidewalk bollards, the 3-foot-high metal posts that secure the 9/11 Memorial and One World Trade Center.

If a catastrophic storm approaches, the tops are removed from the bollards and steel posts are mounted on top to increase their heights to up to eight feet. Then, steel planks are laid on top of one another, bound by adjacent bollards or the façade of the VSC, on either side, depending on location. These create an extremely strong barrier that blocks water and can  prevent permanent damage to electrical and mechanical equipment.

The second ring of protection, known as the at-grade WIPS, includes an 18-foot-wide roll-down door resembling a garage door in the VSC, custom made to fit its dimensions and adapt to the topography of the ground.

The third ring of protection is located below-grade, where more than 140 individual barriers and watertight doors protect critical infrastructure locations underground. This third ring also features an enhanced sump pump system in the sub-basement of the VSC that can pump out 2.2 million gallons of water in 12 hours– a 55-percent increase in capacity from the previous system. This system would only be activated should the floodwaters make it past the first two rings of protection.

“In building the WIPS, we wanted to make sure the aesthetics and the state-of-the-art architecture of the area were maintained,” Bonacci said. “The structures are virtually invisible, unlike sandbags or permanent barriers. When the next storm surge comes, it’s crucial that we’re able to keep the region and our economy moving, and these three rings of protection will enable us to do just that.”


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