July 13 (Reuters) - TransCanada Corp's Columbia Gas Transmission expects the section of the Leach Xpress natural gas pipeline damaged in a blast in West Virginia in early June to return to service on July 15.
Its return, however, requires approval from federal pipeline safety regulators, Columbia said on Thursday in a notice to customers using the pipeline.
The U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA) this week gave Columbia 30 days to respond to a list of corrective actions the agency proposed to improve the safety of the Leach pipe.
Those actions included mechanical and metallurgical testing and enhanced surveillance and monitoring, among other things, according to the federal report made available on Thursday.
Since the June 7 blast, Columbia has identified six other points along the pipeline that PHMSA said are "areas of concern" based on soil conditions and steep slopes or indications of slips.
PHMSA has not identified the cause of the blast but said preliminary investigation suggests the failure was the result of ground movement that caused stress on a weld.
That blast resulted in the ejection of about 83 feet (25.3 meters) of 36-inch (91-centimeter) pipe from the ditch and the loss of 165 million cubic feet of natural gas, PHMSA said. The explosion was in a remote rural area and caused no injuries or evacuations.
The Leach shutdown forced producers using the line to find other pipes to ship gas out of the Marcellus and Utica shale regions of Pennsylvania, West Virginia and Ohio.
Alternative pipelines include Dominion Energy Inc's transmission system, Energy Transfer Partners LP's Rover, Tallgrass Energy LP's Rockies Express, Enbridge Inc's Texas Eastern Transmission and Kinder Morgan Inc's Tennessee Gas, according to analysts at S&P Global Platts.
Columbia said the blast could affect movement of about 1.3 billion cubic feet per day. One billion cubic feet of gas can fuel about five million U.S. homes for a day.
Overall output in the Appalachian region, however, was little changed as producers, like Range Resources Corp and Southwestern Energy Co, found other pipes to ship their gas.
Appalachian output rose from 27.5 bcfd before the blast to as high as 28.1 bcfd on Thursday, according to Thomson Reuters data.
The 1.5-bcfd Leach pipeline in West Virginia and Ohio, which entered full service at the start of 2018, transports Marcellus and Utica shale gas to consumers in the U.S. Midwest and Gulf Coast.
Reporting by Scott DiSavino; Editing by Dan Grebler