Apache, in an update on the spill, said 4 million gallons of so-called produced water soiled a 104-acre area near its Zama production site in Alberta. That's an increase from the original estimate of 2.5 million gallons reported in June.
Apache described produced water as a mixture of oil, natural gas, salt and other minerals that are brought to the surface during extraction processes. It's treated to extract the hydrocarbons.
"Apache believes a pinhole in the exterior plastic liner allowed water to leak into the pipe, which mixed with the sulfur gas, causing stress corrosion cracking and the sudden failure of the pipe," the company said in a statement Friday. "We have determined that the failure occurred on May 5, 2013."
The company said it's been able to contain the area and was moving to the remediation phase.
"Apache's first priority is the safety of the public and protection of the environment," the company said.
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