ANCHORAGE, AK – FEBRUARY 2, 2000 – Alyeska Pipeline Service Company reported today that the backpressure control system for Thompson Pass will be out of service for approximately ten to fourteen days for inspection and repair.  The backpressure control system was shut down Monday morning because a restriction in the piping or valves was causing a higher than normal backpressure.

The day before the backpressure system was shut down, pieces of a pipeline cleaning pig arrived at the Valdez Marine Terminal.  The transmitter/locator for the pig was detected in the backpressure piping in front of one of the backpressure valves.  The locations of the other pig components have not been determined.  During the next week, technicians will inspect the pig trap, isolate the backpressure system, and clean and inspect the backpressure piping to determine if other components of the pig have traveled into the backpressure piping and are inhibiting its proper operation. 

The backpressure control system was installed in 1997 to eliminate vibrations in the pipeline on the south slope of Thompson Pass.  The vibrations experienced while the system is off-line do not create a risk to pipeline integrity.  The residents of the neighborhood near the pipeline in this area have been notified of the situation and the repair schedule.

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