[NYguy]

http://www.nytimes.com/2012/11/08/ny...l?ref=nyregion

Weighing Sea Barriers as Protection for New York


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An aerial view of the hurricane barrier site in Stamford, Conn., in 1986. An expert estimates that any such barrier system to block storm surges in the low-lying areas of New York City would cost at least $10 billion to $17 billion.



By MIREYA NAVARRO
November 7, 2012

As the storm chugged toward the Eastern Seaboard at 3 p.m. on Oct. 27, an engineering crew in Stamford, Conn., was at the ready. It was time. With the click of a computer mouse, machinery on the seafloor groaned into action and a gate was slowly pulled from the deep, locking into place high above the surge from Long Island Sound. Two days later, when storm waters from Hurricane Sandy ripped through the East Coast, much of Stamford, a city of 124,000, sat securely behind a 17-foot-high barrier that easily blocked an 11-foot surge. The Army Corps of Engineers estimates that the two-mile-long barrier system, completed in 1969, helped prevent about $25 million in damage to businesses and homes. The protected area encompasses about 600 acres, including downtown Stamford.

The technology of movable sea barriers, from Stamford’s modest flap gate to London’s mighty 10-gate system in the River Thames, has long intrigued engineers and planners contemplating a solution for low-lying areas of New York City. The notion is that such a system could one day block surges from Long Island Sound and the Atlantic Ocean into the East River and New York Harbor. Now, in the aftermath of the devastating storm, one question is front and center: Should New York armor itself with steel and concrete at a cost of billions of dollars? Mayor Michael R. Bloomberg has expressed wariness about the barrier proposal, saying he is not sure the gates would work well enough. Yet, it is clear that his administration’s view is evolving.

The turning point was Tropical Storm Irene, which in August 2011 mostly skirted the city but pummeled other coastal areas in the region. After that storm, the mayor’s Office of Long-Term Planning and Sustainability asked Dr. Aerts, a geographer and an expert on water risk management and climate, to compare the costs and benefits of barriers with those of smaller-scale changes like building levees around sewage treatment plants and elevating subway stations.

Dr. Aerts, who is expected to present a draft of his findings in January, estimates that any barrier system would cost $10 billion to $17 billion. New York would need $10 billion to $12 billion more to shore up the areas on the sides of the barriers, he added. Still, he said, the city should consider building the barriers.