Hurricane Sandy, resilience and infrastructure

01/11/2012 — Leave a comment

Resilience and common cause considered in the wake of hurricane Sandy

One of the fairly obvious lessons from Hurricane Sandy is the vulnerability of underground infrastructure such as subways, road tunnels and below grade service equipment to flooding events.

The New York City subway system is 108 years old, but it has never faced a disaster as devastating as what we experienced last night”

NYC transport director Joseph Lhota

Yet despite the obviousness of the risk we still insist on placing such services and infrastructure below grade level. Considering actual rises in mean sea level, e.g a 1 foot increase at Battery Park NYC since 1900, and those projected to occur this century perhaps now is the time to recompute the likelihood and risk of storm surges overtopping defensive barriers.

Putting essential services below grade is fine if you want to maximise aesthetics or the real estate value of property, but not so fine when a flooding event like Hurricane Sandy turns up, and potentially even worse if you’re Oyster Creek Nuclear Power Plant the oldest nuclear plant in the US and coincidentally located in New Jersey.

The combined effects of storm climatology change and a 1 m [sea level rise] may cause the present NYC 100-yr surge flooding to occur every 3–20 yr and the present 500-yr flooding to occur every 25–240 yr by the end of the century.

Ling et al 2012

Nuclear power plants need cooling water, which means that they need to be on a river, ocean or estuary and that in turn makes them vulnerable to flooding, especially so if essential equipment is located below the projected flood level. Further if the plant is sited on a bay or estuary these geographical features also tend to concentrate storm surges so these plants will be exposed to proportionally higher rise in storm surge levels.

Luckily Oyster Creek plant was offline for its bi-annual refuelling, nor were the on-site emergency generators knocked out by the rising flood-water. So it appears that that plant’s defenses were a little more resilient than those of Fukushima. Of course the refractory period before the storm made landfall undoubtedly assisted the operators to prepare for the ‘day after the day after’, unlike the bolt from the blue events of Fukushima.

There’s no question that the storm that battered the East coast was an extreme event, in fact so extreme that the flooding levels at Oyster Creek exceeded NRC alert criteria for that site. As to how close those flood levels were to the NRC’s flooding Design Basis of Oyster Creek that’s another story, as is whether the NRC should revise the probability of such extreme weather events in light of global warming.

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