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Repairs to leaking Cook Inlet natural gas line expected in coming days

  • Author: Alex DeMarban
  • Updated: December 2, 2017
  • Published March 27, 2017

With the temperature finally rising, Hilcorp Alaska said Monday it plans to begin repairs on a leaking undersea natural gas line in Cook Inlet by the middle of next week.

The plan to begin repairs within 10 days is based on current weather and ice forecasts, the company said in its statement issued by Lori Nelson, external affairs manager. The National Weather Service predicts daily highs in the 30s for the western Kenai Peninsula in the coming week.

For more than a month, Hilcorp has said it could not safely repair the leak because ice pans and the Inlet's strong tides pose too great a risk to repair divers and boats.

Hilcorp also said Monday it had "safely completed" temporary oil production shutdown at the Middle Ground Shoal Field, where the leak is occurring. The shutdown over the weekend allowed the company to reduce the amount of natural gas, mostly methane, moving through the leaking pipeline. That, in turn, has reduced the leak rate.

Pan ice is abundant in Cook Inlet on March 9 in the general area of the natural gas leak from a Hilcorp Alaska pipeline. (Jacob Cunha / Alaska Department of Fish and Game)

The 8-inch pipeline, installed in the mid-1960s, delivers fuel gas to power four offshore platforms, including two active platforms where small amounts of oil are produced. The pipeline leak was discovered Feb. 7, though the line appears to have been leaking since December.

The leak is about 80 feet underwater, northwest of Nikiski, about 3 ½ miles off the coast.

Hilcorp said Monday the new, lower leak rate is 100,000 cubic feet of gas daily, on average. That is enough to fuel about 140 homes in Southcentral Alaska in December, based on average household consumption rates made public by Enstar Natural Gas Co.

That's down significantly from the original average leak rate estimate – 275,000 cubic feet of gas daily – first reported in February.

The leak has generated concerns about dangers to salmon and other fish, as well as to endangered Cook Inlet belugas and other wildlife. The concern for fish and other gilled animals is that methane would replace too much oxygen in the water column.

On Friday, the company released a statement saying a buoy released to collect water quality data near the leaks found "no meaningful adverse impacts to water quality."

"Hilcorp believes the samples also demonstrate that current water quality does not pose a threat to wildlife," the company said.

The Alaska Department of Environmental Conservation, however, has said more data is needed to accurately assess water quality and determine wildlife impacts.

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