Enbridge says no coverup in its underestimate of N.W.T. pipeline spill. At first, Enbridge had reported a spill of four barrels from its Norman Wells pipeline. Now the estimate is between 700 and 1,500 barrels. Griese reports that Enbridge officials say the oil leaked out of a pinhole opening in the pipeline.
Enbridge's own statement at http://www.enbridge.com/ says that the original estimate "did not take into account the subsurface impacts". Enbridge had expected that the amount of oil underground would not be significantly different than the oil on the surface. Enbridge notes that there are "no impacts to moving water", but does not address any potential impact on groundwater.
Pinhole leaks in pipelines pose a significant problem for landowners with oil pipelines. Subsurface pipelines can leak large quantities of oil over long periods of time without the leaks being detectable to pipeline company monitoring equipment. Areas around leaks can be significantly contaminated, but the contamination may never be discovered unless it rises to the surface of the ground or, more often, the pipeline company has some reason to dig up the area. For example, contaminated areas have been discovered frequently during the construction of new pipelines adjacent to existing pipelines.
At present, neither pipeline companies nor energy regulators are taking any initiative to locate contaminated areas along existing pipelines. It may be time for property owners to demand extensive soil testing along oil pipelines on an ongoing basis to ensure that their land is not being contaminated by undetected leaks in pipelines.