BY SEAN COCKERHAM

McClatchy Washington Bureau (TNS)

WASHINGTON – The Obama administration unveiled a new rule Monday that’s designed to help prevent a repeat of the deadly 2010 Deepwater Horizon explosion and oil spill in the Gulf of Mexico, and to bolster the president’s claim that it’s safe to start drilling in the Atlantic Ocean.

The rule calls for tighter requirements on blowout preventers, a supposedly fail-safe device that failed miserably in the 2010 catastrophe. Eleven workers died, and millions of barrels of oil spilled into the Gulf of Mexico. The announcement came as President Barack Obama has proposed opening waters off the coasts of North Carolina, South Carolina, Georgia and Virginia to drilling.

“These proposed measures are designed to further build on critical lessons learned from the Deepwater Horizon tragedy to ensure that offshore operations are safe,” Interior Secretary Sally Jewell said in announcing the rule.

The announcement came a week before the fifth anniversary of the Deepwater Horizon disaster April 20. Asked why it took so long for the rule, Jewell said, “This is complicated stuff, and there are a lot of different assessments done post-Deepwater Horizon to understand exactly what went wrong.” The rule will be finalized after a 60-day public comment period.

Investigators have found that the Deepwater Horizon spill resulted from a series of systemic failures by the oil company BP and its contractors, including corporate mismanagement and failed government oversight, and that problems with the blowout preventer contributed to the disaster.

The blowout preventer is the last line of defense to stop explosions and spills if something goes wrong offshore.

It’s a five-story stack of valves designed to sever the drilling pipe and seal the well in case of emergency. In the Deepwater Horizon spill, according to the federal Chemical Safety Board, the drill pipe buckled under pressure and kept the blowout preventer from sealing the well.

The Chemical Safety Board found that the blowout preventer’s blind shear ram, a device with cutting blades, punctured the pipe and sent oil and gas rushing to the surface of the gulf.

The new requirements call for double shear rams “with an enhanced capability to shear pipes,” as well as more controls over the inspection, maintenance and repair of blowout preventers. Double shear rams can mean quicker and cleaner cuts, but they also serve as a backup if something doesn’t work.

There also are new requirements for testing sub-sea well containment equipment and for cementing wells.

The Interior Department said those requirements were designed to address the fact that “the blowout preventer ... was a point of failure in the Deepwater Horizon event, but several other barriers failed as well.”

 The Interior Department said the new requirements were expected to cost the industry $883 million over 10 years.

But in Monday’s conference call with reporters, Jewell said the rule built on improvements that the oil industry had already made since the spill, so some of that money has already been spent.

“We don’t anticipate that these rules are going to materially make a difference in terms of the economics of the offshore oil and gas industry. ... These are rules that are largely in place in terms of practices by many of the drilling operators,” she said.

Environmental groups lobbying to stop Obama’s plan to drill the Atlantic argue that, while improving blowout preventers is important, there are many other risks with offshore drilling.

The National Ocean Industries Association, a trade group for the offshore drilling industry, said it was reviewing the new requirements and didn’t have an immediate comment on the specifics.

“The federal regulators promised a big rule, and at more than 200 pages they certainly delivered,” association president Randall Luthi said in a statement. He said the group wanted safety to be a top priority, but he added that 60 days might not be enough time to understand the Interior Department’s new regulations.