Cooper, Robertson & Partners Architecture, Urban Design. Flood Mitigation in

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1 Cooper, Robertson & Partners Architecture, Urban Design Flood Mitigation in Page Museum 1 Design

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5 COOPER ROBERTSON The devastating effects of Hurricane Sandy on New York City s infrastructure inspired a transformation in the practice of flood mitigation. The location of the new Whitney Museum of American Art adjacent to the Hudson River is particularly sensitive to water level rise and storm surge. The design of the building by Renzo Piano Building Workshop in collaboration with Cooper Robertson anticipates the effects of climate change and protects the Museum s staff and collection from water level rise. In the original design, the team elevated the lobby above the FEMA recommendation of nine feet to ten-plus feet. All galleries begin on the fifth floor and extend upward with no permanent gallery or art storage below level five. When Superstorm Sandy hit New York City in October 2012, the museum was well under construction and basic elements of the building s design were already in place to protect the structure in the case of flood. The timing of the storm enabled the team to see how the building could withstand a serious flooding event. The structure withstood the storm well, but unprecedented water levels brought over six million gallons of river water into the building s 30 deep basement. The devastating effects of the storm on New York City s infrastructure inspired a transformation in the practice of flood mitigation, and the timing of the Whitney Museum project has put the project team at the forefront of addressing future resilience. Flood Mitigation Page 5

6 Following the storm, FEMA revised its flood zone maps, recommending a 13.5 foot elevation for building on the Whitney site. With the sense that that elevation still seemed too conservative, the Whitney team conducted an international search for an advisor to assist in developing a revised flood elevation recommendation. They selected WTM Engineers of Hamburg, Germany, and their partner, the Franzius Institute for Hydraulic, Waterways, and Coastal Engineering of the Leibniz University of Hanover, two organizations well versed in protecting an urban environment from floods. The Franzius Institute undertook extensive study of New York Harbor and its environmental history and advised that the building should be protected up to a 16.5-foot elevation. Based on these studies, the design team worked with WTM to devise modifications, both temporary and permanent, for the Whitney s structure that will protect it against future storm events. Page 6

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10 RECALIBRATION AND RETROFITS In the case of flooding, the main goal is to preserve the ground floor as effectively as possible, which will ensure that the entire building is safe guarded. To do this, the team examined all possible water infiltration points within and above the 16.5 foot protected elevation. Reinforced concrete walls surround the basement and protect the building on four sides, but the truck and staff entry points on the west side of the building are at street grade, a sixfoot elevation. To protect this possible entry point, the team enlisted Walz and Krenzer, manufacturers of watertight doors for navy vessels, to manufacture floodgates that would prevent water from entering through these portals. The floodgates consist of a 10-inch thick aluminum plate with a hinged door, operated by a turning wheel that seals water out against steel plates embedded into reinforced liner walls. Two Whitney facilities staff members can together close the gates in case of emergency. To incorporate the floodgates into the design of the building, the Cooper Robertson team redesigned the surrounding structure to accommodate them. The reconstruction on the west side of the building required the removal of pre-cast concrete from the alreadyconstructed stair tower. During this removal, the pre-cast concrete on the levels above it had to be temporarily secured in place while the new section incorporating the floodgate could be installed. A crucial element in the Whitney s flood mitigation strategy is continuity; the floodgates only work if the rest of the building is continuously sealed. Waterproof membranes behind the secondary reinforced concrete walls shield the structure from flooding. Aqua-seal is used to seal 3D concrete penetrations created for electrical conduits, gas, electrical service, and piping, maintaining the structure s integrity due to a storm surge. Page 10

11 COOPER ROBERTSON The team also devised temporary protective elements to be deployed in anticipation of flooding. In the hours before a weather event, a contractor will bring the Whitney s temporary barriers from a nearby warehouse and assemble them on site. A continuous concrete curb on the building s plaza bolsters aluminum posts that are bolted into the ground to them hold stacked aluminum logs. The temporary barriers will protect the lobby s large expanses of glass wall that could be vulnerable to pressurized water. To this end, extensive additional structure was added to the plaza design to accommodate the additional weight. The plaza s drainage system was also reconceptualized by engineers Jaros Baum & Bolles so that any leakage or splashover drains away from the dry area. Floodgates: Custom designed by Walz and Krenzer, these watertight doors are used for navy vessels. They are used at the Whitney s truck and staff entry ways, considered the most vulnerable points for water intrusion. Flood Mitigation Page 11

12 WORST CASE SCENARIOS An additional change to the original building design included the rethinking of the building s emergency energy sources. Instead of the 1,000-gallon fuel oil tank originally planned for the museum, the Whitney s insurance advisors suggested accommodating the largest tank possible. Therefore, the building has a 4,000 gallon tank in order to provide with as much energy as possible in an emergency in order to keep the building s systems, particularly the pump system, running. The team did precise calculations to account for all possible flood scenarios, including the failure of these or other functions. For example, if the pumps should fail, it was determined that 14 inches of water would then flood the basement. Therefore, all placement of electrical equipment was adjusted to sit above a 14-inch elevation. In cases where this was not possible, a concrete barrier provides protection. Wall system barriers like the one showed above act as a third layer of support during flood conditions. The Whitney facilities team can construct these systems a day in advance of a flood warning. The system was designed by WTM Engineers of Hamburg, Germany. Page 12

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14 In the worst case scenario of water level rise above 16.5 feet, the structure is designed to survive flooding of the lobby level, to deflect the force of any debris impact load, and to prevent any stray building materials from blowing off the structure and causing damage or injury. The severe impact of a flood of this magnitude on the city trumps the concern for resuming building operations as quickly as possible. Instead, the design gives the Whitney staff peace of mind that the building will not cause harm to its community during any future unprecedented weather events. The Whitney s MEP systems have been redesigned to withstand storm conditions equal or worse than Hurricane Sandy. Page 14

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