Pembina Pipeline Corp. has been cleared of all fault in relation to an oil pipeline break under the Red Deer River on June 15 of last year.
The Energy Resources Conservation Board released a report blaming extreme rainfall for the break at a river crossing about five km north of Sundre.
“This incident happened because of an unprecedented level of rain,” ERCB communications officer Davis Sheremata said on Tuesday.
“That led to an incredible flow of water that uncovered the pipeline, submitted it to excessive external stress and led to the failure,” said Sheremata.
Subsequent investigation showed that the Red Deer River is in a delta at the area of the break, joining with a number of tributaries that were all affected by the extreme flooding, he said.
“At the end of the day, we believe that Pembina did not contravene our regulations in any way, so no enforcement action is required against them.”
The company estimated that 28.1 cubic metres (177 barrels) of oil were released into the river as a result of the break.
ERCB’s report states that there was a delay in closing the valve, which “may have contributed” to additional oil being released into the water before the spill was contained. Company officials estimated that the delay contributed about 10 cubic metres of the total amount of oil spilled.
Oil spilled from the break travelled 33 km downstream, into Gleniffer Lake. The lake was subsequently closed to boaters while people in the area were warned not to use local water sources.
Propane-powered “scare cannons” were used to warn wildlife away from oily shorelines while crews from Western Canada Spill Service began work on cleaning up the spill.
Cleanup was completed on June 25, with boaters allowed back onto the lake the following day.
Pembina Pipelines continued trucking potable water into the area until June 27, when health officials declared the water safe for consumption and reopened water intakes.
The ERCB estimates that a total of 23.55 cubic metres (148 barrels) of oil was recovered from the failed pipeline.
A diversion channel was excavated later in the summer and a dam was built, with the river diverted by July 27, enabling construction of a new trench. The damaged pipeline was removed and about 800 metres of new pipeline installed in August.
Although Pembina is not being held at fault for the break, ERCB has issued a bulletin advising all pipeline companies to be especially vigilant in inspecting and monitoring river crossings during the next few weeks, as ice starts to break up and rivers become subject to flooding.
Details of the ERCB report are available online at www.ercb.ca