ANCHORAGE, AK. November 27, 1996. -- Alyeska Pipeline Service Company reported today that evidence of hydrocarbons has been found in the soil near the trans-Alaska pipeline in Thompson Pass, at pipeline milepost 776. Alyeska is conducting an on-site investigation to determine the source and extent of the hydrocarbons. The hydrocarbons were detected by soil gas probes.

This section of the pipeline has been under detailed scrutiny to determine if pulsations in the pipe in this area could affect pipeline integrity. The pulsations result from crude oil turbulence as it moves through steep sections of the pipeline in Thompson Pass. Alyeska is completing a detailed evaluation of the effect of the pipeline vibration on several irregularities in the pipe. The irregularities include several small dents and one section of pipe that is slightly out of round or “ovaled”. All of the irregularities are within U.S. Department of Transportation guidelines for normal operating conditions. The probes that found the hydrocarbons are placed near the section of “ovaled” pipe. This section of pipe also includes two small dents.

Alyeska recently began installing soil probes in the ground along the pipeline near the source of the pipe pulsations in Thompson Pass to provide additional leak detection. Using this system, the probes are placed in the ground and gas from the soil is drawn into testing equipment, using a vacuum system, for an immediate scan for indications of hydrocarbons. Samples can also be drawn into sample bags for additional testing.

Equipment necessary to eliminate the pipe pulsations is being designed and will be installed next summer.

The pipeline is currently operating at 1.46 million barrels per day.

The Joint Pipeline Office has been notified of the incident.

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