By David D. Dunlap
Elevated floors are an imperative in flood-prone areas like the site of the new building on West 26th Street, only 400 yards from the Hudson River.
West Chelsea was hit hard by Hurricane Sandy in 2012. So was Lower Manhattan, where Savanna, the real estate investment concern behind the 26th Street building, owned two office towers that were knocked out by flooding.
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The building lot straddles two zones designated by the Federal Emergency Management Agency as 100-year and 500-year flood plains. That does not mean inundation once every century (or five centuries). It means there is a 1 (or 0.2) percent chance of inundation every year. In a 100-year flood plain, that equates to a 26 percent chance of flooding over a 30-year mortgage, the city’s Office of Recovery and Resiliency noted.
Local regulations enacted since Hurricane Sandy generally require new commercial buildings in 100-year flood plains to be elevated or floodproofed to the “design flood elevation,” at least one foot above the anticipated high-water mark, or “base flood elevation,” of future floods.
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