The Transportation Safety Board of Canada said a lack of field measurements to determine the exact location of buried pipelines contributed to a pipeline rupture and leak at an Enbridge site east of Edmonton in 2017.
On Feb. 17, 2017, crews were using a horizontal directional boring technique to install a new pipeline in Sherwood Park. The boring was happening in an area where pipelines were already in place.
During the pipeline installation, the 24-inch Line 2 pipeline operated by Enbridge was struck and punctured. About 1,000 cubic metres of petroleum crude oil condensate was released after the pipeline was ruptured.
The TSB found that the horizontal directional boring took place without a field-measured confirmation of the exact location and depth of cover for the Line 2 pipeline at the crossing with the Grand Rapids Pipeline, the new pipeline being installed.
“Measurements taken from an adjacent pipeline were used instead, which were highlighted within the project documentation to indicate that a field verification had not been completed,” the TSB said in a news release Monday.
The TSB also said a ground disturbance checklist completed at the beginning of the shift incorrectly indicated that visual depth confirmation had been completed for all pipelines to be crossing during the boring operation. This led to missed opportunities to further assess the drill path, according to the TSB.
Most of the oil condensate released during the leak was recovered, according to the TSB. The National Energy Board continues to monitor remedial actions on the site.
Following the leak, Enbridge conducted a review of internal communications, including clarifying technical terminology related to pipeline crossings. The TSB said Grand Rapids Pipeline enhanced ground disturbance and pipeline crossing procedures and checklists.
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