by Stephen Solecki
Since the occurrence of Hurricane Sandy nearly three years ago, there has been much talk about better addressing flood concerns and buildings across New York City. As a ‘shock’ event, Sandy can be thought of as a turning point that has helped garner attention for climate related hazards. As a stand-alone event, Sandy cannot directly be attributed to climate change, but such events may become more frequent in the future. For many New York City communities that exist in low lying areas, especially those designated as Zones V or A (the most at risk), how to best deal with the threat of flooding from extreme events has been a primary question. As of the end of May 2013, the City of New York enacted what is referred to as a ‘freeboard’ policy. This mandate requires that the vertical difference between the lowest floor of a building and the base flood elevation (the predicted level floodwaters rise for a 1% event in a given year – uncommon but not impossible) be increased by two feet for one and two family homes, and one foot for non-residential homes for all buildings in the current FEMA 100-year flood zone.
Of course, there has been little discussion regarding who would pay for these needed changes and the challenges building owners face. There has been no evidence that the City or New York State would fund freeboard modifications. So, is it worth building owners to pay out of pocket to build up to code or should buildings in the most at risk areas simply be transformed into buffer areas to reduce the effects of storm surge on the second most at risk areas? Even for buildings just situated within the 100 year flood zone, retrofitting buildings up the federal flood resistant standards will be no easy task. One and two family homes are often built on narrow lots, making elevating construction difficult. Semi-attached or attached homes pose a unique problem; if only one building needs to be modified, the other still has to be modified as well to maintain the integrity of both structures. For multi-story buildings, ground and basement level apartments would need to likely be abandoned, leading to an economic loss through less units being available for rent. Buildings that have commercial ground floors would likely have commercial activity hindered and accessibility issues could develop. Buildings pose unique challenges when it comes to integrating the freeboard policy, but there may be alternatives as illustrated by examples of buildings that to resisted the impacts of Sandy.
The Arverne by the Sea community, despite being located on the Rockaway Peninsula which experienced immense damage, faced little damage as a result of its storm-surge conscious design. The buildings are equipped with a powerful subterranean drainage system, built to handle storm surge flooding. Sewers around the development were reconstructed to prevent the system from being overwhelmed during heavy precipitation events, utility lines relocated underground and water resistant transformers integrated. At the ground level, innovative urban design was instrumental is minimizing flooding; wide streets and a natural beach grass buffer along the beach (along with a boardwalk) were all helpful in reducing the impact of storm surge, particularly with reducing destructive wave energy. Residential units are well fortified as they sit atop concrete foundations that are embedded in the ground with wooden pilings. Steel framing, a blend of cement shingles, and hurricane resistant windows comprise all buildings. In Williamsburg, an area called the Edge also sustained minimal damage. Over 500 steel and glass constructed buildings along the waterfront have generators on the eighth floor and concrete panels were used on the exteriors to minimize building motion in high winds, and the entrance was built as high as possible. It should be noted that storm surge waters did surpass bulkheads, but they did not reach the buildings – this time at least. The Edge is planning to integrate better designed gas turbines which will produce uninterrupted emergency electric power for the building during in case of a loss of power. These two communities have taken rather simple approaches to make their buildings resist the elements; the costs invested in the aforementioned adaptive methods likely outweigh the costs that would have been endured had no proactive measures ever been taken to increase the resiliency of these communities.
In essence, while changing building codes has been a major choice for addressing potential flooding related to storms, it not the best solution. Resiliency needs to be better integrated into urban form. It is possible for this to be done economically, but the real issue is how to handle dealing with the freeboard policy. Potentially, it could be costly for some landowners to handle raising the elevation of their building. Other means of dealing with flooding should be considered in light of the freeboard policy. Passive techniques, those that allow floodwaters to pass in and out of a structure, could work for some buildings. Having a subterranean parking lot could fulfill this purpose and also serve to deal with a secondary issue (the need for more available parking city-wide). Sometimes simple alternatives work the best and prove to be the most effective at achieving an overarching goal.