ANCHORAGE — The owner of an underwater pipeline spewing processed natural gas into Alaska’s Cook Inlet has lowered pressure in the line to reduce the leak.
Repairs will continue to wait for ice in the inlet to clear because it’s too dangerous to immediately start work, according to Hilcorp Alaska, LLC.
The 8-inch leaking pipe sends natural gas from shore to four petroleum platforms in the inlet, home to a population of endangered beluga whales.
An analysis of gas flow indicated the pipeline probably started leaking in mid-December. Hilcorp started looking for a leak in January, and on Feb. 7, a helicopter crew spotted gas bubbling to the surface about 4 miles off shore in 80 feet of water.
Hilcorp lowered pressure in the line March 4 and estimated that leak was reduced to 210,000 to 310,000 cubic feet of gas daily.
Hilcorp lowered the pressure in the line again Monday and estimates it’s leaking 193,000 to 215,000 cubic feet daily.
Divers would have to contend with strong tides, winter weather and floating pans of ice. Ice conditions remain too dangerous, Hilcorp said in a statement.
“Hilcorp’s response team is ready and the necessary equipment has been staged to commence repair operations as soon as conditions permit a safe working environment for response personnel,” the company said Tuesday. Repairs should take several days.
The U.S. Pipeline and Hazardous Materials Safety Administration on March 3 issued a proposed safety order requiring the line to be repaired by May 1 or shut down.
Environmental groups have called for an immediate shutdown. Two groups have given required 60-days’ notice that they intend to sue. Processed natural gas is almost 99 percent methane that will create a low-oxygen dead zone threatening beluga whales, other marine mammals and fish, according to the groups.
The pipeline once carried crude oil and Hilcorp said shutting off pressure could allow residual crude to escape.
The company said it has conducted baseline air and water sampling and continues flights over the bubbling gas.
“To date, no significant impacts to wildlife or the environment have been observed and the release does not pose a threat to the general public,” the company said.
Hilcorp purchased the pipeline and other oil and gas facilities from XTO Energy, Inc., in September 2015. The 8-inch line also leaked in June and August 2014. Clamps repaired the line.