The southeastern U.S. is “highly dependent on pipeline supplies from Colonial and, ultimately, Colonial flows form the baseline of U.S. East Coast supply,” Robert Campbell, head of oil products research at Energy Aspects Ltd. in New York, said in a note. The longer the mainlines are offline, “the more upward pressure will be placed on U.S. East Coast fuel prices, while downward pressure will be exerted on U.S. Gulf Coast product prices.”

December gasoline futures rose as much as 21.56 cents, or 15 percent, to $1.6351 a gallon, the biggest intraday gain for an active contract since 2008. The New York Mercantile Exchange contract, which is for supplies delivered into New York Harbor, traded at $1.5775 at 1:37 p.m. Singapore time.

The explosion and fire comes as the U.S. oil industry faces a backlash from environmentalists opposed to building new pipelines, including the controversial $3.8 billion Dakota Access oil pipeline. Last year, the Obama administration rejected the Keystone XL project. In early October, climate change activists disrupted oil flows by turning off valves in several remote pumping stations along the Enbridge Inc.’s main pipeline, which runs from Canada to the U.S. Midwest.

1.3 million-barrel-a-day gasoline line

Colonial, owned by a group that includes Koch Capital Investments Co. and a unit of Royal Dutch Shell Plc, had to shut its 1.3 million-barrel-a-day gasoline line after an 7,370-barrel leak was discovered Sept. 9. It built a temporary bypass that allowed it to resume shipments on Sept. 22, which its had planned to remove between late-October and mid-November. Now both the gasoline mainline and the mainline that transports diesel and jet fuel are shut.

Colonial — and to a lesser extent the smaller Plantation Pipe Line Co. — play a key role in supplying the U.S. Southeast because there aren’t any refineries between Alabama and Pennsylvania that produce substantial quantities of transportation fuels. The region is supplied primarily by pipelines from refineries along the U.S. Gulf Coast, according to the U.S. Energy Information Administration.

While Colonial has a capacity of 2.6 million barrels a day of refined products, the Plantation pipeline carries just 700,000 barrels a day.

Several major U.S. refiners gained in after-market trading as gasoline’s premium to Brent crude, a theoretical profit margin for many fuel makers, jumped as much as 60 percent to $18 a barrel before paring gains to about $14. Phillips 66, which operates a refinery near New York City, gained 1.7 percent to $82.50 on the New York Stock Exchange after closing at $81.15 a share Monday. Valero Energy Corp. and Marathon Petroleum Corp. also rose.

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