Pressure caused by shifting soil over time is being blamed for the rupture of an 18-inch natural gas pipeline in Hamilton Heights Saturday.

Crews with Gulf South Pipeline Co. settled on that conclusion as they worked Sunday to repair a hole left when the pipe blew out behind a home in the 100 block of Drusilla Lane at about 11 a.m. Saturday.

&#8220There’s some subsidence in the ground,” said Stephen Gonzalez, a public information officer with Gulf South. &#8220It’s what probably caused the line to break.”

The conclusion is not a new one. When the city’s main water line burst near the Port of Vicksburg in mid-September, leaving all city residents without water for about 36 hours, city officials attributed the break to ground movement.

Saturday’s incident did not result in fire and no one was injured, but it caused the evacuation of about 150 residents on Drusilla Lane and in the Forest Hill apartment complex, across Fisher Ferry Road, prompting the Vicksburg chapter of the American Red Cross to open a shelter at Hawkins United Methodist Church on Halls Ferry Road.

Until just after 10 p.m., when the bad spot was located, crews arriving from various locations in a four-state footprint of the Houston-based Gulf South gas company spent much of the day easing pressure from the line by venting at spots east of the break.

Earlier, tests conducted at the scene by the city Water & Gas Administration determined the evacuations were necessary. Readings of airborne natural gas at 5 parts per million are considered dangerous. Though the air tested at 1.3 parts per million or less through the evening hours Saturday, tests conducted at Drusilla Lane and at the apartments showed levels of 4 or higher just before their evacuations.

Though Gulf South is among the suppliers of natural gas to customers in Vicksburg, residential gas service was not affected by the break. The line is a Monroe-to-Jackson transmission line for Gulf South’s network of pipelines that cross parts of four states in the Southeast. Its only major feed-in was to the U.S. Army Corps of Engineers’ Research and Development Center just a mile up the road on Halls Ferry. The service there was quickly switched to a municipal line to maintain gas service.

Gulf South is one of two companies with major expansion projects in Mississippi, with Warren County as part of their paths.

Gulf South’s project, the East Texas to Mississippi Expansion Project, is awaiting environmental approval from the Federal Energy Regulatory Commission on a 42-inch pipeline that will run through south Vicksburg. It would cross into Vicksburg just south of the Baxter Wilson Power Plant and continue across U.S. 61 South near Grange Hall Road and run across the county line with Hinds near the southern edge of Bovina Cutoff Road.

Gulf South has filed seven eminent domain suits in Warren County Court in attempts to persuade affected landowners to sell either portions of land or easements.

The other, the Southeast Supply Header, is being proposed by Houston-based Spectra Energy Corp. and will pass through extreme southern Warren County between the Yokena and Cedars communities. An environmental review is expected by mid-March.

The latter has received a pledge from Warren County supervisors to grant a fee-in-lieu of property taxes if the project hits company-assigned benchmarks. Gulf South has said it wants to have one granted for the project as well, but, so far, supervisors have put off a decision.