"Get your facts first, and then you can distort them as much as you please." (Mark Twain)

Thursday, September 22, 2005

Well, Blow Me Down 

The general hostility toward science displayed by this administration (and, to be fair, widespread throughout our generally anti-intellectual culture) has real world consequences, as demonstrated by this excellent article from the Mobile Register:
In the days after Katrina, as hundreds of oil-producing platforms remained off line -- and some continued to leave a conspicuous trail of petroleum in the Gulf of Mexico -- federal officials insisted to Congress that they were doing everything they could to make this critical infrastructure stable during hurricanes, designing platforms to withstand Category 5 storms.

But federal and industry documents obtained by the Mobile Register show that the latest design criteria for offshore oil and natural gas platforms require only that these structures withstand winds and seas typical of a borderline Category 2/Category 3 storm, well below the Category 4 and 5 winds that affected Gulf oil fields at least four times in the last five years.

Under the latest International Building Code, a model adopted by many states and localities, beach houses on many of the Gulf's barrier islands would be constructed to withstand stronger winds than is required by the design criteria for offshore platforms....

On Sept. 6, Rebecca Watson, the Department of the Interior's assistant secretary for Land and Minerals Management, told members of Congress that "current design standards require industry to design facilities to Category 5 storm criteria."

But the Register has found that federal regulations require that facilities be designed to withstand a 100-year storm as defined by the American Petroleum Institute, a nonprofit trade organization.

In the documents used to calculate design loads for offshore platforms -- called API 2A-LRFD and API 2A-WSD -- the institute defines a 100-year storm in the northwestern Gulf of Mexico as having 80 knot one-hour average winds. According to Twisdale and wind engineers from Texas Tech University, that should be equivalent to about 115 mph in sustained one-minute winds, the scale used to gauge hurricane strength.

In wind estimates provided by ConocoPhillips Inc., three-second wind gusts produced by API's 100-year storm would be 134 mph. Such gusts are typically associated with one-minute sustained winds of about 109 mph, according to standard calculations used by the American Society of Civil Engineers.

This means that the wind design standards for the offshore structures approximate an upper Category 2 or lower Category 3 hurricane (110 mph is the threshold between Category 2 and Category 3; 130 mph is the Category 3/Category 4 threshold).

Though engineers working with industry and the U.S. Minerals Management Service have described Ivan and Katrina as once-in-a-thousand-years events, other engineers who have worked with hurricanes say that such storms are not so unusual.

Twisdale said his researchers at Applied Research Associates are still analyzing the data, but their preliminary estimates indicate the wind-field associated with Katrina was not a once-in-a-thousand-years event, but rather in the range of a once-in-a-hundred-years event.

That's the kind of storm that the industry and federal officials say they are preparing for in the Gulf. But Katrina's Category 4 or 5 winds were far in excess of Petroleum Institute standards, and so were the waves produced by the storm.

And the result?
On Tuesday, federal officials released reports of at least 64 spills associated with Gulf platforms following Katrina.

Fortunately - and this is one of those areas where market forces actually may be more effective than regulation, given that the destruction of offshore platforms represents a significant economic loss to their operators - some companies have overbuilt the regulatory requirements:
Some oil and gas companies have elected to build platforms to higher standards than those required by the federal agency.

For example, ConocoPhillips said its plans for an offshore Liquefied Natural Gas terminal about 12 miles south of Dauphin Island at the mouth of Mobil Bay has been designed with a 150-year storm in mind. According to ConocoPhillips spokesman David Knox, such a storm would produce three-second wind gusts of about 143 mph, which would typically be associated with 120-mph sustained winds during a mid-range Category 3 storm. The facility could simultaneously absorb waves of about 58 feet, he said.

Knox said company officials decided to build to the higher standard after looking at the damage done by Ivan's maximum sustained winds in the open Gulf, which were about 140 mph.

Still, the wind gusts ConocoPhillips is designing for are below the wind gusts that homebuilders on Dauphin Island are expected to build for. According to the American Society of Civil Engineers, residential construction on the sandy shores of Dauphin Island should withstand a minimum of 150-mph three-second gusts.

And, while it may be expensive to build better platforms, it is by no means impossible:
The industry has demonstrated that it may be possible to construct platforms to withstand Category 5 winds, and the waves and currents often associated with those winds. Officials with the BP energy company in Houston said their state-of-the-art $1 billion Thunderhorse platform, one of the newest in the Gulf, was designed to withstand 147-mph sustained winds and waves of at least 100 feet. He described the design criteria as consistent with a 1,000-year storm.

The Thunderhorse platform, located about 150 miles south of New Orleans, listed 20 to 30 degrees earlier this year after Hurricane Dennis passed by. But industry officials said the platform had not yet been placed in service when the damage occurred and the damage may not have resulted from the hurricane.

Please do go read the article in its entirety - it is somewhat difficult slogging, but well worth it - and keep its lessons in mind as Rita approaches the Texas coast with its dense concentration of petroleum infrastructure.

 

Comments:

 

Cool Blog, I never really thought about it that way.

I have a Hurricane Katrina blog. It pretty much covers hurricane related stuff.

Thank you - and keep up the thoughts!
 
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