A slow leak in an underground section of the trans-Alaska pipeline has been sealed, an official with Alyeska Pipeline Service Co. said Thursday.
The pipeline company late last month added the finishing touches to a 60-inch metal sleeve that had been placed over the isolation fitting where the tiny leak was discovered in May, along an underground portion of the 800-mile-long pipeline that carries the state's economic lifeblood.
The leak was stopped in July when the sleeve was installed, but conical ends were added more recently to complete the work.
The weep, found by Alyeska at a pump station between Delta Junction and Glennallen, was initially one drip per second and was immediately contained. After a tar membrane covering the coupling was removed, the weeping slowed significantly.
About half a million barrels of oil a day flow through the pipeline, providing the primary source of state revenue. The leak and repair never caused a slowdown or stoppage in oil flow, said Michelle Egan, corporate communications director at Alyeska.
The pipeline company inspected several other sites for similar problems and found none.
"This was unique to that site," she said.
Alyeska personnel removed as much contaminated soil as possible, about 7 cubic yards, excavating about 15 feet below the surface before finding a "large boulder that was impassable and where the leaked product had pooled," the Alaska Department of Environmental Conservation said in a press release issued Thursday.
"Utility lines and the TAPS mainline block valve" prevented further excavation, leaving a small underground area of contaminated soil that will be monitored by the state agency's Contaminated Sites Program, it said.