The transaction includes Dominion Energy Questar Pipeline, its subsidiaries and certain associated affiliates which include White River Hub and Overthrust Pipeline among others.
The transaction includes the assumption of existing debt of $430m.
Originally, Dominion Energy signed a definitive agreement in October 2021 to divest the assets in a bid to reduce debt and support its capital plan.
As part of the transaction, Southwest Gas created a new subsidiary to own the Questar Pipeline Entities.
The new subsidiary is named MountainWest Pipelines Holding Company (MountainWest). Colleen Larkin Bell will lead the business and will directly report to Southwest Gas Holdings executive vice-president Karen Haller.
During the first half of 2022, Questar Pipeline Entities are expected to be rebranded under the MountainWest brand.
Southwest Gas president and CEO John Hester said: “Natural gas pipelines are essential to the nation’s energy future, which includes alternative sources such as renewable natural gas and hydrogen blended gas, and MountainWest brings increased scale and diversification to our business portfolio.
“MountainWest will focus on adding value by accelerating growth opportunities and positioning the company as a leader in the evolving energy landscape.”
Questar Pipeline owns US Federal Energy Regulatory Commission (FERC)-regulated transportation and underground storage assets in Utah, Colorado, and Wyoming, including related services and processing entities.