NTSB: Expansive clay pulled gas lines loose before Mississippi explosions
The National Transportation Safety Board said in a report released Thursday that underground gas pipes pulled loose from their fittings as spongy Yazoo clay soil expanded and contracted with rainfall caused natural gas explosions in January that destroyed two homes in Jackson and killed Clara Barbour, 82.
The NTSB found Atmos Energy Corp. detected leaks before the blasts but evaluated them as not severe enough for prompt repair, the report said. Investigators said the leak at the Barbour home was detected Nov. 17, 2023, and was classified as nonhazardous. A separate leak was detected Dec. 1, 2023, and was scheduled for repair within three years, the report said. Atmos re-evaluated leaks after the explosions and found some were more serious than initially reported, the board said.
Investigators said Yazoo clay, a soil layer that expands when wet and contracts in drought, can cause pipe disconnections and that the couplings installed by an Atmos predecessor are not resistant to being pulled out. The NTSB recommended Atmos locate and replace those couplings, the report said, and noted regulators had warned about expansive soils since 2008. The board also cited a 2018 Atmos explosion in Dallas that killed one person and injured four, saying expansive soils had been identified previously as a factor.
The report faulted Atmos for insufficient risk assessment, repairs and public education on how to respond to gas leaks and urged regulators to increase oversight. “Atmos has had significant safety shortfalls in recent years,” the board wrote. “Thus, Atmos’s multistate operations require broader oversight.” Investigators added that Atmos applied different safety procedures in different states and said if stricter rules used in Kansas had been followed in Mississippi the explosions could have been prevented.
Atmos spokesperson Bobby Morgan said safety remains “our highest priority” and that the company will “work diligently in the coming days and weeks to evaluate the findings as part of our ongoing safety efforts to further our vision to be the safest provider of natural gas services,” Morgan said in a statement. Atmos distributes natural gas in Colorado, Kansas, Kentucky, Louisiana, Mississippi, Tennessee, Texas and Virginia, the company said. The NTSB report said the Jan. 24 explosion that killed Clara Barbour also injured her husband, and a Jan. 27 blast about three-quarters of a mile away leveled one home and burned a neighboring house without causing injuries.
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