Divers find natural gas pipeline leak in Alaska’s Cook Inlet
By DAN JOLING
Repair work is underway for a pipeline that has spewed hundreds of thousands of cubic feet of processed natural gas into Alaska’s Cook Inlet, home to endangered beluga whales and other marine mammals.
The 8-inch (20-centimeter) diameter pipeline supplies gas for power to four Hilcorp Alaska, LLC production platforms. A spokeswoman said Monday that divers over the weekend discovered a 2-inch (5-centimeter) hole at bottom of the pipeline where it rests on a boulder in the sea floor.
“Divers have identified the leak location, and are working to prepare the site to allow for the installation of a temporary clamp,” Lori Nelson said.
A more permanent fix will follow. The pipeline will not be put back into service until permanent repairs are completed, the line has been pressure tested and regulators sign off on a restart, Nelson said.
Cook Inlet covers 180 miles (290 kilometers) from the Gulf of Alaska to Anchorage. Besides beluga whales, it provides habitat to humpback whales, Steller sea lions, northern sea otters and important salmon populations.
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 about 4 miles (6.4 kilometers) off shore in 80 feet (24.4 meters) of water.
Floating ice made it too dangerous for divers to reach the leak sooner, according to Hilcorp. The company lowered pressure in the line but said minimal pressure was required. The line once carried crude oil, and if gas were removed, seawater could carry out residual crude oil.
Environmental groups contend the flow of gas is dangerous for wildlife, but Hilcorp has said it has seen no evidence of environmental damage.
Hilcorp is investigating two other Cook Inlet potential leaks. Oil sheens were spotted April 1 at a production platform, and the source was initially reported as a pipeline running between two platforms. However, in an email Monday, Nelson said the pipeline was pressure tested Saturday and inspected by divers Monday and found to be undamaged and in good working order.
Hilcorp also emptied a natural gas pipeline after discovering that volumes of natural gas moved from a production platform did not match what was received by a processing facility on shore.