ExxonMobil says an analysis by an independent lab concludes that original manufacturing defects caused the rupture of a pipeline on March 29.
An estimated 150,000 gallons of tar sands flowed through a residential neighborhood in Mayflower after the break in the 65-year-old Pegasus pipeline.
Hurst Metallurgical Research Laboratory inspected the damaged section, which was removed from the ground, exposing a 22 foot gash.
After three delays in releasing the report, on Wednesday, it was presented to the federal Pipeline and Hazardous Materials Safety Administration and ExxonMobil.
The report was not immediately released to the public or the media, but a written statement sent by ExxonMobil spokesman Aaron Stryk said, “The root cause of the failure can be attributed to original manufacturing defects – namely hook cracks near the seam.”
The Ohio company that made the pipe, Youngstown Sheet and Tube, is no longer in business.
The statement also said there were no findings that indicated internal or external corrosion, and that contributing factors included “atypical pipe properties, such as extremely low impact toughness and elongation properties across the ERW seam.”
Glen Hooks with the Sierra Club said, “If that information is true, that should give us even more concern about the portion of the pipeline that is in the Lake Maumelle watershed.”
That’s the primary source of drinking water for central Arkansas and many, including Republican 2nd district Congressman Tim Griffin, have asked ExxonMobil to move it, which the company has resisted.
“How much of the 1940's-era pipeline is also operating under the same manufacturing defects?” Hooks asked. “I think there is a growing call for keeping the Pegasus pipeline shut down and/or moving it out of the Lake Maumelle Watershed, and this report just really lends some credence to that argument.”
ExxonMobil said it has conducted supplemental testing to ensure a similar incident does not occur again.
22 homes were evacuated near the site of the spill, while other residents who live in the area, but were not evacuated, have expressed fears about the long-term health effects of their exposure to the fumes.
Last month, Arkansas Attorney General Dustin McDaniel and U.S. Attorney Christopher Thyer announced they had filed a joint lawsuit on behalf of the Arkansas Department of Environmental Quality and the federal Environmental Protection Agency.
They said the spill violated environmental laws and wanted civil penalties imposed on ExxonMobil.
Wednesday evening, Aaron Sadler, a spokesman for the Attorney General, said the office had not seen the report and had no comment.