Gas leak raises fears over sea floor pipelines
Alaska’s picturesque Cook Inlet is home to endangered beluga whales and wild salmon — and a spider web of oil and natural gas pipelines on the sea floor, many of them placed there five decades ago.
Cook Inlet’s petroleum production is often overshadowed by Alaska’s giant North Slope oilfields, but the inlet is in the spotlight as millions of cubic feet of natural gas spew from an underwater pipeline owned by the inlet’s largest petroleum producer, Hilcorp Alaska LLC.
The federal agency that oversees pipeline safety has “strongly recommended” that Hilcorp develop a safety management system for its pipelines.
Environmental advocates are demanding immediate pipeline inspections by federal authorities, not Hilcorp, in the area with earthquakes and some of the world’s strongest tides.
“The age of the pipelines significantly increased the risk of failure, especially when coupled with the harsh offshore Cook Inlet environment,” Kristen Monsell, an attorney for the Center for Biological Diversity, wrote in a letter to the federal Pipeline and Hazardous Material Safety Administration.
Hilcorp has not said whether it will craft the safety management system but insists the age of its pipeline system does not pose a threat and would not affect maintenance and inspection requirements already enforced by state and federal regulators.
“Hilcorp is ready, willing and able to make the necessary investments to keep us working in Alaska for many years to come,” said David Wilkins, Hilcorp Alaska senior vice-president, in an email.
The inlet lined by mountains stretches 290 kilometres from the Gulf of Alaska to Anchorage. Humpback whales, Steller sea lions, northern sea otters and salmon swim in its waters.
Besides earthquakes that periodically rattle Cook Inlet, tides fluctuate more than 7.6 metres and are so strong that they move carsize boulders along the sea floor, said Lynda Giguere, spokeswoman for the Cook Inlet Regional Citizens Advisory Council, set up after the Exxon Valdez oil spill to promote environmentally safe marine transportation.
Hilcorp entered the Alaska market in 2012 and owns 15 of the 17 Cook Inlet petroleum platforms. The gas leak is in a pipeline carrying processed natural gas from shore to four platforms, where it’s burned to provide electricity.
An analysis of gas flow indicated the pipeline probably started leaking in mid-December and initially spewed up to 8,780 cubic metres of natural gas per day. Hilcorp lowered pressure in the line to reduce the flow to 2,407 to 3,257 cubic metres per day.
Divers on Monday in 24.4 metres of water found a five-centimetre gash on the bottom of the line where it rests on a boulder embedded in the sea floor. Repairs are underway.