Williston Basin Interstate Pipeline Company, the wholly owned natural gas transmission pipeline subsidiary of MDU Resources Group, has announced that it will expand firm transportation capacity on its existing Grasslands Pipeline by 54%.

The 253-mile Grasslands Pipeline was placed in service in late 2003, running from the Powder River Basin in northeastern Wyoming to western North Dakota, where it connects with the Northern Border Pipeline.

The expansion project will add an additional 75 million cubic feet of gas per day (mmcf/d) to its existing capacity of 138mmcf/d. In early July 2008, Williston Basin conducted an open season on the expansion project seeking customer commitment for additional transportation capacity.

Strong customer demand for the pipeline capacity pushed the project to full capacity of 213mmcf/d. The project cost is expected to be about $28 million and the targeted in-service date is August 2009, pending timely receipt of the necessary regulatory approvals.

Terry Hildestad, president and CEO of MDU Resources, said: We built the Grasslands Pipeline with future expansion in mind, and we are more than pleased to have reached full capacity on the pipeline in just over five years.