What Sandy Taught

 

November 2013

What Sandy Taught

Following the devastation of Superstorm Sandy, engineers sprang into action to help recovery and rebuilding efforts. What lessons did they learn?

BY EVA KAPLAN-LEISERSON

What Sandy TaughtHalf of a house left standing, blue sky where the rest should be; a lone car floating down a flooded street; debris scattered like a child's game of Pick-Up Sticks; waves the only rider on a roller coaster tossed into the ocean.

The images of Superstorm Sandy were dramatic. The former hurricane hit U.S. soil in late October 2012, causing at least 159 U.S. fatalities (directly or indirectly) and $65 billion in damages and economic losses. More than a year later, communities, businesses, and individuals are still recovering.

Engineers have played a key role. As one PE put it, after first responders react to a crisis, the engineering community often provides a second-wave response. Some who contributed to that effort shared their Sandy experiences and insights as the one-year anniversary passes.

Not the Wind, But the Water
Sandy was "an extraordinarily large hurricane," according to the National Hurricane Center. But its primary damage was not from wind.

Flooding overwhelmed preparations. The storm smashed the record for water height in the New York Harbor, notes Malcolm McLaren, P.E., president and CEO of the McLaren Engineering Group, a New York-based company that has done a lot of Sandy-related work. "Not by six inches or a foot, [but by] four feet. There was a tremendous surge. The waves that accompanied that are like nothing ever seen before."

A sampling of McLaren Engineering staff tasks after Sandy: inspecting 20,000 structures, examining bridge foundations and piers (some of the company's engineers are also certified divers), and conducting bathymetric surveys to ensure that water channels were clear of debris. The company has also been designing repairs to buildings, bridges, piers, and boardwalks.

One of the key observations McLaren, an NSPE member, made is that most of the failures occurred in connections. Beams, boards, and planks often fared well, he explains, but almost universally they failed where they were connected together. These elements have to be designed for uplift, he says, and the loads that come with rising water and waves.

Flooding was also the common theme in work by the Geotechnical Extreme Events Reconnaissance (GEER) team, which coordinates National Science Foundation-sponsored reconnaissance efforts and collects data following natural disasters. PEs make up a large portion of the organization's steering committee and advisory panel.

According to the GEER report, the storm's slow movement combined with a high tide to cause "devastating storm surges" into the coastlines of New York and New Jersey and flooding in densely populated urban areas "at an unprecedented scale."

Youssef Hashash, P.E., is professor of civil and environmental engineering at the University of Illinois at Urbana-Champaign and coleader of the GEER team that surveyed Sandy impacts. He notes the effects on underground infrastructure and utilities—including roadway and subway tunnels—from severe flooding in metro areas. Although the tunnels were pumped out fairly quickly, Hashash says, damage to electrical systems caused by the corrosive salt water delayed return to service.

A key question the PE poses: Do we prevent flooding or build infrastructure to accommodate it? This issue requires a lot of thought, he says. "You can't just move the city to higher ground."

Protecting the Coast
In the coastal regions, wave action led to a great deal of erosion, Hashash explains. According to the GEER report, the damage "points to the need to consider inundation, storm surge forces, erosion, and wave action in the design of foundations, shore protection systems, and surface facilities."

Thomas Herrington, EIT, ocean engineering program director at New Jersey's Stevens Institute of Technology, is also assistant director of the Center for Maritime Systems, which houses the Coastal Engineering Research Laboratory. A Stevens team from the lab has been working closely with New Jersey's Department of Environmental Protection and the Governor's Office of Recovery and Rebuilding to evaluate coastal protection needs and examine alternatives to stabilize the coast and protect communities.

Herrington says that building codes instituted after legislation in 1968 created the National Flood Insurance Program, now managed by the Federal Emergency Management Agency, were effective in coastal areas. Buildings on pilings above the flood elevations survived, he explains, while the water undermined structures that predated those codes and pushed them off their foundations. "Engineers have the design tools they need," he says. "Where structures were built to appropriate codes, things worked well." The challenge is how to translate these lessons to an urban environment, he continues.

FEMA has issued new Advisory Base Flood Elevation Maps for New York and New Jersey based on Sandy. The maps indicate how high structures should be to minimize damage from future events and to decrease the cost of flood insurance. New York Mayor Michael Bloomberg has issued an order for flood-resistant design referencing the new maps. New Jersey has also adopted the new maps as the standard for construction along its coastline.

In addition, the Army Corps of Engineers is conducting a comprehensive study to address the flood risks of vulnerable coastal populations in areas affected by Sandy. It will include an evaluation of the performance of nature-based infrastructure. The study aims to provide a risk reduction framework, incorporating future sea level rise and climate change scenarios. (For more on sea level rise and the Army Corps, see June 2013 PE, p. 16.)

Bearers of Bad News
After the hurricane, the New York City Department of Buildings asked the engineering community for help in inspecting damaged homes. NSPE member Joseph Pasaturo, P.E., principal of AVT Engineering, stepped up.

The PE had already been informally evaluating structures with other members of the Staten Island chapter of the New York State Society of Professional Engineers. (Pasaturo is the chapter president.) The engineers were quickly checking whether houses were safe enough for people to retrieve their possessions.

Pasaturo joined in with the engineering teams that were inspecting houses more officially. Many homes he examined were converted 1920s and 1930s summer bungalows that didn't meet current standards for foundation reinforcement or depth. The velocity of the stormwater and soil erosion created voids in the soil and damaged the foundations, the PE explains.

Engineers had to become the bearers of bad news, he says, telling people that they couldn't simply raise their houses to meet the new flood elevation standards and qualify for flood insurance. They might have to rip out entire foundations and "basically start from scratch," which insurance companies could object to.

Pasaturo is now writing reports for customers battling insurance companies that he says are minimizing storm-related damage. Some companies are bringing in engineers who aren't licensed to practice in New York to examine houses, he explains. Pasaturo, who serves as a member of the New York State licensing board, cautions that engineers not licensed in the state could be subject to disciplinary action for providing engineering services in a state in which they are not licensed.

Calls to Action
A critical first step in preparing for extreme weather events is simply recognizing our vulnerability. Only after making that realization can we begin to address the challenges, say experts.

Troy Morgan, P.E., is senior engineer for Exponent, a consulting firm with expertise in natural and human-induced disasters. He examined properties and facilities post-Sandy to determine the cause and origin of damage.

In New York, water reached well above the 100-year flood elevation, he says. Although there's still lack of consensus, he explains that some research has shown that the event corresponded to somewhere between a 500-year and 1,000-year flood event, based on the risk models used. The takeaway for him: Engineers have to set a threshold that they design for, but there is always a chance it's going to be exceeded.

Malcolm McLaren points out that engineers can design for a 1,000-year flood, but is it worth it? What is the premium to do so? "People need to understand there is a risk tolerance that really needs to be defined and then design accordingly," he says.

But in many cases, small changes can make a big difference. Many of Sandy's impacts could have been easily mitigated, says Thomas Herrington, for instance the flooding of Battery Tunnel in Manhattan or most of metropolitan New York losing power because all the substations were below or at flood levels. It's not hard to put barriers in front of tunnels or elevate the substations, he says. However, proactive steps haven't been taken because an event like this hadn't previously occurred in the area.

Gregg Piazza, P.E., an associate at Mueser Rutledge Consulting Engineers, explains that his firm is working with a company that adapted its technology to protect against terrorist attacks into a removable flood wall system. According to the NSPE member, Mueser Rutledge is helping RSA Protective Technologies and New York City determine ways to use the barriers to protect subway entrances.

Piazza's company is also designing and rebuilding Casino Pier (scene of the iconic roller coaster photo) after it collapsed in Seaside Heights, New Jersey. In addition, Mueser Rutledge provided engineers to the Department of Buildings' teams for inspections.

In terms of buildings, another commonly cited lesson learned from Sandy was the need to move electrical and mechanical equipment out of the basement in case of flood events. Residential buildings were shut down for sometimes months because equipment or backup diesel generators were damaged by water, says Morgan. Locating those items out of the basement "is simple, but has to be done."

More broadly, while local actions are important, so too is regional collaboration. The Hurricane Sandy Rebuilding Strategy presented to President Obama was developed by a high-level task force that includes the secretaries of a number of U.S. agencies and other policy leaders. The report notes that since disasters don't respect jurisdictional lines, rebuilding efforts must take into account interdependencies. "A series of uncoordinated hazard mitigation measures may yield unintended consequences and could ultimately decrease resilience in the long term," it says.

Or, as Herrington puts it, even if one municipality takes proactive steps to maintain beaches and protect the community from damage, the one next door might not, which makes the whole region vulnerable. Thinking regionally is challenging because politics are local, he says. But "fixing one hole in the dike at a time won't serve us very well in the long-term."

More Questions
Some questions have no easy answers. For instance, where should building be permitted and what kind of flood control systems are necessary?

Morgan, who is from California, says that the important lesson is not to avoid building anything, but to know the hazards. "If you build in a location that you know is susceptible to potentially large flood events, you need to, at a minimum, raise the structure," he says. In terms of rebuilding, it's key to know that the flood hazard is not what you thought it was, he continues.

The PE notes that cities around the world, such as in the Netherlands and Russia, have installed massive rotating flood gates. He believes the U.S. needs to consider similar options for cities along the Atlantic seaboard that are major ports and economic centers. "A major center of commerce shutting down for an entire month can be catastrophic for the entire country, not just for the region," he says.

But the cost of doing so is prohibitive. If a flood gate costs $10 billion, "who's going to bear those costs?" asks Morgan. In addition, such a step comes with engineering challenges. A seawall can't be built all the way around the New York Harbor and Long Island.

The good news is that conversations that were difficult to start in September 2012 have now become more serious, says the PE.

Again and Again?
There's still debate about whether severe weather events like Hurricane Sandy are becoming more frequent. But, as Herrington points out, "it only takes one to ruin your day."

What's clear is that the economic costs of such disasters add up. According to the Hurricane Sandy Rebuilding Strategy, last year alone 11 weather and climate events caused total damages of $110 billion.

And as the report notes, sea level rise caused by ocean warming and ice melting will increase the risks of inundation for any given coastal storm. "These projections of increased risk cannot be overlooked in the development of hazard mitigation and recovery plans for the future," it states.

The National Institute of Building Sciences' Multihazard Mitigation Council has estimated that for every dollar invested by FEMA in hazard mitigation, the U.S. receives at least $4 in benefits.

But Morgan believes that in order for large investments to occur, the science has to be able to show convincingly that these types of flood events are not as rare as we once thought. "If we can convince ourselves that the economic impact is large enough, then we will install flood gates at some point," he says. "I am optimistic about it actually happening, I just don't know if it will be in my lifetime."

Herrington cites a recent talk by a FEMA mitigation director: "Never look back; the past has already happened. Look forward to what could be worse in the future." Says the professor, "that should be our standard to design to."

 

Rebuild By Design

In June, the Hurricane Sandy Rebuilding Task Force launched Rebuild by Design, a competition "aimed at promoting resilience through innovation for the Sandy-affected region." The competition will not only provide design solutions to issues that are too large or complex for towns to solve themselves, but also implement winning proposals with public and private funding.

Submissions may range from large-scale urban and multifunctional green infrastructure to small-scale distributed flood protection measures and resilient residential structures. The competition is also expected to promote regional interdependencies.

The Stevens Institute's Herrington, who has seen some proposed concepts, says they are "absolutely amazing."

Contributing teams have been selected. Learn more at rebuildbydesign.org.