Additional pipeline infrastructure is being planned to help carry natural gas away from the state.

The Williston Basin Grasslands Pipeline, a 250-mile natural gas pipeline from Gillette to Dunn County, N.D., was built in 2003 for $70 million.

It is operated by the Williston Basin Interstate Pipeline Co., a subsidiary of MDU Resources Group Inc., of Bismarck.

Tim Rasmussen, an MDU Resources spokesman, said the 16-inch line initially carried 80 million cubic feet of coal-bed methane from the Power River Basin to a compressor station near Manning, north of Dickinson. The pipeline ties into a network that delivers natural gas throughout the United States.

The line currently pipes 138 million cubic feet of natural gas a day. An expansion project is planned in August to bump the daily capacity to 178 million cubic feet, Rasmussen said.

Rasmussen said capacity has been added in phases as the demand for natural gas increased.

"As the Powder River Basin has increased production volumes, there is a need to get that natural gas to market," he said.

The expansion, pegged at more than $15 million, consists of an additional compressor station in Campbell County and one in Golva, in western North Dakota's Golden Valley County, Rasmussen said.

The pipeline was designed to carry a maximum of 200 million cubic feet of natural gas a day, Rasmussen said.

Last week, El Paso Pipeline Partners {M7announced that its wholly owned subsidiary, Wyoming Interstate Co., will expand its system upstream of the Opal Hub to accommodate more natural gas from the Uinta Basin and Wamsutter production areas. The capital cost of the expansion is estimated at $55 million.

Wyoming Interstate Co. has executed long-term transportation contracts with four shippers for a total of up to 255 thousand dekatherms per day.

The expansion also supports shippers' transportation needs upstream of El Paso Corp.'s Ruby Pipeline, which will extend from Opal to Oregon and is planned to be in service by March 2011, according to a press release.

In Wyoming, Wyoming Interstate Co. plans to install three miles of 24-inch diameter pipeline and reconfigure one compressor at its Wamsutter station.