Neither of the full page advertisements on safety features of the design of the Northern Gateway Pipeline, appearing in the Citizen April 3rd and 10th, mention what former Enbridge design engineer Bill Middagh was most concerned about - the elevation drop from the last pumping station down to Kitimat.
For phase one of the pipeline, this last pumping station will be at Burns Lake. This means that the oil will be pumped to the top of a 4,600 ft. summit at Kilometre 973 and then have to descend by gravity under its own weight through the future site of the Houston pumping station at 2,300 ft, then siphon over a 3,400 ft. summit down to the Kitimat terminal at 590 ft. above sea level.
In order to maintain sufficient operating pressures to prevent column separation from occurring (like the airlock forming when you are trying to siphon gasoline), the oil flow will have to be throttled by valves in the path of its descent. In its hydraulic design, Northern Gateway modeled sudden 95 per cent closure of all valves at the same time as 100 per cent closure of terminal valves, and showed that no section of pipe would exceed its maximum allowable operating stress. They did not model what would happen if only terminal valves closed while an upstream pumping station remained in operation.
Under such circumstances, all oil pipelines located in the Kitimat River valley would exceed its (72 per cent of yield) maximum allowable operating stress by a considerable margin. If the pipe did not actually rupture it could undergo plastic deformation that would permanently weaken the steel and seriously reduce its ability to withstand later overpressure events. The people of Kitimat are justifiably fearful of the ticking time bomb that this pipeline, with three phased flow and pressure increases over its 30 year life, represents for their community.
Chris Peter
Prince George
