On July 18, Urban Green Council hosted a Building Resiliency Task Force technical roundtable, Build Your Own Bathtub, featuring two Task Force members who were deeply involved in that process. They shared their experiences about specific NYC projects they’re working on as well as the more general challenges that buildings face as they prepare to protect themselves against flooding. Spirited discussion covered some of the crucial details needed to take a good idea – floodproofing with storm barriers to protect buildings in flood zones – into a reality that will keep structures safe during the next big storm.
Phillip White (Kohn Pedersen Fox) discussed how various floodproofing strategies are being used depending on site conditions and the desires of the owner. The building code is undergoing an update and the city issued emergency rules after Superstorm Sandy, so some things that were allowed if building permits were granted before the storm may no longer be – if you’re working on a project, check the code carefully before making any decisions. Phillip said one of his goals is to keep streets vibrant and attractive while strengthening walls or adding barriers; if this isn’t done, areas in flood zones are at risk of acquiring a “bunker-ish” look (my word, not his!). For example, perhaps specially designed glass in the building façade can be used, fish tank style, as part of the flood barrier. However, these new approaches sometimes need customized architectural solutions to hide supports and stanchions, so new designs can often incorporate resiliency improvements more elegantly than can retrofits.
Aine Brazil (Thornton Tomasetti) pointed out that in flood zones in Manhattan and elsewhere, many existing buildings are built right up to the property line. This can make adding external barriers a technical and permitting challenge. Even if these issues are resolved, there are still egress issues to consider; once removable barriers have been installed, provisions must be made for getting over them in case of emergency. This is a concern in all cases but especially if the wall is more than two or three feet high, as it can significantly add to the distance that temporary ramps would have to project into the street. One way or another, New York will have to address this problem in order to improve the resiliency of existing buildings in the city. Aine also brought up an easy-to- overlook but important point: when removable barriers are the chosen design solution, there is a unique operations and maintenance issue of stacking and storing the large panels (potentially hundreds of them) in between events. And they must be stored carefully – if just one panel is missing, the whole flood barrier system will be compromised.
Many audience members and the speakers acknowledged the unfortunate fact that even the best barriers can fail, so buildings should be prepared with secondary or backup strategies. This can include barriers for doorways (behind removable sidewalk flood barriers), sump pumps to deal with leakage from barriers, and good emergency planning that takes the worst-case scenario into account.
For me, one of the most interesting challenges posed is when a building is not freestanding and therefore can’t surround itself with barriers. In this case, water can enter the building through the party walls shared with neighbors, if those adjacent buildings are not protected themselves. This is the case in most of the city – and if you’re trying to protect just your own building, good luck trying to plug all the holes in those party walls on the block! One solution is to protect the block in its entirety, where all buildings could share in the cost and maintenance of removable barriers. This is a more resilient solution but adds an organizational challenge onto the already formidable architectural and engineering ones. However, if a workable way to share these barriers can be developed for whole blocks, many more buildings in our city will likely be protected, so it’s a task worth undertaking.