Pipeline, fishing factions argue safety issue
The U.S. gas pipeline and fishing industries are at odds over what should be done to keep fishing vessels from striking pipelines on the seabed.
Pipeline witnesses told a House merchant marine subcommittee hearing in New Orleans the locations of offshore pipelines should be noted on marine navigation charts, and commercial fishing vessels should be required to consult them.
Fishing industry witnesses said offshore pipelines should be buried deep enough so that even if a ship pushed through a silt bottom there would not be any danger.
The hearing was prompted by an accident last Oct. 3 in which the Northumberland fishing boat struck a pipeline off Port Arthur, Tex. Eleven crew members were killed, and three were injured (OGJ, Oct. 9, 1989, p. 29).
The $900,000 vessel was destroyed by fire. Damage to the pipeline and loss of natural gas is estimated at $750,000.
The Northumberland was 1/2 mile offshore, west of the entrance to Sabine Pass in 9-11 ft of water, when it struck and ruptured a Natural Gas Pipeline Co. of America (NGPL) 16 in. line from four platforms. The ship was fishing for menhaden, which typically is caught very close to shore.
When the line was laid in 1973, it was buried 8 1/2-10 ft below the seabed but had been uncovered by erosion. The line was shown on navigation charts.
Shallow water traffic
Robert Pasteris, engineering vice-president for NGPL, said large vessels should be banned from shallow water areas in which pipelines are located.
“The best maintained pipeline can become instantly exposed if a ship traveling at or below the sea bottom strips off its cover,” he said.
Davis Allen, president of Zapata Haynie Corp., said a requirement for boats to avoid buried pipelines would effectively halt navigation along the Louisiana coast and much of the Texas coast. That’s because 191 pipelines make landfall there.
Allen, whose firm operated the Northumberland, said a survey is needed to determine if pipelines are properly buried but need examine only pipeline sections in less than 23 ft of water.
John K. Lauber, a member of the National Transportation Safety Board (NTSB), said it is “a recognized practice” that menhaden vessels, while operating in waters close to their drafts, often run close to, scrape, or move through a soft bottom of silt and mud.
He said his agency is gathering data on whether available technology can detect a buried offshore pipeline and measure the burial depth.
Rear Adm. William Merlin of the U.S. Coast Guard said new technologies such as side scan sonar, robotic underwater cameras, and other electronic means might be considered for surveying submerged pipelines.
NTSB, which is investigating the Northumberland accident, has made some interim recommendations to the Transportation and Interior departments.
The board says it will issue a full report on the Northumberland accident.
It said Transportation, as the main federal agency responsible for pipeline safety, is best able to organize and coordinate a federal-state-industry effort to determine the danger of offshore pipelines to marine vessels and to propose effective methods to inspect and maintain burial depths.
It recommended that Transportation immediately issue a cautionary notice about exposed pipelines to fishing vessels that operate close to their draft or that operate bottom dragging equipment.
It said Transportation and Interior should locate all offshore pipelines in the Gulf of Mexico and establish methods to check their burial depths.
NTSB pointed out that Transportation’s office of pipeline safety has counted 21 accidents in which vessels have damaged offshore pipelines since 1985.
The board said, “The magnitude and urgency of the problem are unknown because of the lack of complete information about the number, type, and location of pipelines in the Gulf of Mexico and the lack of effective surveillance procedures to verify that offshore pipelines remain safely buried.
“The absence of regulations to require that burial depths be maintained for offshore pipelines increases the likelihood that other buried offshore pipelines may also become exposed above the natural bottom of the gulf.
“The jurisdictional complexities among the various federal and state agencies and the applicability of existing regulations create additional difficulties.”