International Dredging Review

International Dredging Review

The National Transportation Safety Board has asked the Western Dredging Association (WEDA) to inform its members of the events at Tiger Pass Louisiana on October 23 1996 where the Bean Horizon dredge Dave Blackburn and the tug G.C. Linsmier were destroyed by fire.

WEDA executive director L.M. Patella stated “this incident and the service provided by our organization clearly demonstrate the need for the WEDA Safety Committee. Please support Tom Verna chairman of the committee and become a member of the committee. Our industry needs your support and expertise in this area.”

At 4:50 a.m. of October 23 1996 the crew of the dredge Dave Blackburn dropped a stern spud in preparation for continued dredging operations. The spud struck and ruptured a 12-inch-diameter submerged natural gas steel pipeline owned by Tennessee Gas Pipeline Company. The pressurized (about 930 psig) gas released from the pipeline enveloped the stern of the dredge and the tug G.C. Linsmier. Within seconds of reaching the surface the gas ignited and the resulting fires destroyed the dredge and tug. All 28 crewmembers from the dredge and tug escaped into the water or onto nearby vessels.

Bean Horizon was awarded the Tiger Pass contract on September 20 1996 in an area where several underwater pipelines were located. The Corps of Engineers provided Bean with Corps drawings showing their approximate locations. The Tennessee Gas pipeline was shown crossing Tiger Pass at centerline station 614+20 or 61420 feet from the point where the Pass joins the Mississippi River. Post-accident measurements determined that the pipeline actually crossed the pass at station 615+12 or about 92 feet downstream from the location indicated.

One of the contract provisions with which Bean complied required them to notify the pipeline owners by certified mail at least seven days before dredging within 500 feet of their pipelines and also that the owners verify the pipeline locations.

On September 22 Bean began dredging about 1000 feet southwest of the pipeline location on the Corps drawing. The initial dredging plan was to move toward the Gulf of Mexico and away from the pipeline. On October 17 the crew received weather reports predicting rough weather so the dredge supervisor decided to move to a more sheltered area to the northeast near the point where they had begun but still southwest of the pipeline. According to the supervisor the plan was to begin dredging there then move northeast toward the pipeline. Tennessee Gas was notified by phone that the dredge would be near the pipeline. The project engineer said he questioned a Tennessee Gas supervisor several times about the pipeline’s exact location and was told that it was marked by two pilings one near each side of the pass. These pilings were located at about station 618+10 about 300 feet downstream of the actual pipeline crossing.

At about 2 p.m. on October 19 an inspector from Tennessee Gas boarded the dredge and using information and a sketch provided by her supervisor established a 100-foot safety zone in the area of the pilings. In order to avoid damage to the pipeline dredging in that area was to be done with suction pumps only and not the cutterhead. Bean’s daily quality control reports showed that the pipeline location identified by Tennessee Gas personnel did not match the location shown on the Corps of Engineers drawings.

Using only suction pumps dredging proceeded in the area where the pipeline was believed to be located. The daily quality control report indicated that the ladder struck an object believed to be the pipeline about 15 feet Southwest of the site identified by the inspector. Dredging then continued to the northeast to within about 130 feet of the actual pipeline location. On October 20 because of improving weather the supervisor decided to return the operation to the Gulf of Mexico end of the channel where weather conditions had previously halted work. The Tennessee Gas inspector left before the dredge was moved with an agreement that the company would be notified when the dredge returned to the area of the pipeline.

After completing work at the lower end of the pass the dredge returned at about 9:40 a.m. October 22 to an area about 140 feet northeast of the area identified as the pipeline location. The crew began dredging to the northeast believing themselves to be outside the safety zone and moving away from the pipeline. In reality they were moving toward the pipeline which was about 100 feet away. By 9:30 p.m. the cutterhead had crossed over the pipeline without incident.

On October 23 at 4:50 a.m. after stopping to clean the cutterhead and reset the swing anchors the crew lowered a spud at about station 615+12 and directly into the pipeline.

Bean had established a safety program for its vessels that included initial crew-changeout monthly abandon ship and man overboard drills and weekly all-hands safety meetings. These drills and safety meetings were recorded in the vessel’s logbooks and written summaries were submitted to the company Loss Control Department. Dave Blackburn crewmembers stated that no crew list crew team assignment or other crew accounting procedure was in place on the vessel.

Initially the U.S. Coast Guard on-scene commander believed that 33 crewmembers were aboard the Dave Blackburn and G.C. Linsmier at the time of the accident. The Coast Guard incident log indicates that 30 crewmembers were aboard the dredge. The required accident report (CG-2692) submitted by Bean indicated that 28 people were aboard the dredge including three crewmembers from the G.C. Linsmier who were having breakfast aboard the dredge when the pipeline ruptured. No crewmember interviewed after the accident knew with certainty how many people were on the vessels at the time of the accident. They stated that they used an informal survey and quick head count to determine that no one was missing.

A review of Bean’s emergency response instructions and the Dave Blackburn’s station bill revealed no provision for accurately accounting for the number of people on board the dredge at any specific time. The Safety Board is concerned that without a system to account for all on board the risk is substantial that in the event of a serious emergency some people may be left behind with possibly life-threatening injuries without anyone knowing of their plight until it is too late.

The Safety Board has investigated several accidents aboard passenger and fishing vessels in which passenger and crew accountability was an issue. In this accident the speed and extent of the gas release and fire placed all crewmembers in grave danger. Fortunately despite the early hour most crewmembers were awake alert and able to respond quickly to the emergency. Given the rapid ignition of the gas and the extent of the damage to the vessels had this accident occurred while the crew was sleeping serious injuries or fatalities may have occurred. The Safety Board concluded that in even a slightly more serious accident Bean’s emergency procedures were not adequate to account for and facilitate the rescue of missing crewmembers increasing their risk of serious injury or death. The Safety Board has therefore made the following safety recommendation to Bean Horizon Corporation:

Amend your emergency response procedures to require that at accurate count of all persons aboard your vessels be maintained at all times by someone in authority on the vessel and be accessible to the vessel operating department on shore so that the number will be readily available to emergency responders in the event of an on-board emergency.

Because the Board’s concern about emergency procedures for dredges is not limited to this one operator the Safety Board makes the following recommendation to the Western Dredging Association:

Inform your members of the circumstances of the pipeline rupture and fire in Tiger Pass Louisiana and urge them to amend their emergency response procedures as necessary to require that an accurate count of all persons aboard the vessels be available at all times.

The Safety Board issued Safety Recommendations P-98-25 to the Research and Special Programs Administration; P-98-26 and –27 to Tennessee Gas Pipeline Company and M-98-123 to Bean Horizon Corporation; P-98-28 to the Interstate Natural Gas Association of America and P-98-29 to the American Petroleum Institute.

The National Transportation Safety Board is an independent federal agency with the statutory responsibility “to promote transportation safety by conducting independent accident investigations and by formulating safety improvement recommendations” (Public Law 93-633.) The Board is vitally interested in any action taken as a result of its safety recommendations and would appreciate a response regarding action taken or contemplated with respect to these recommendations. Contractors are asked to refer to Safety Recommendation M-98-124 in their reply. Call 202-314-6469 for more information.

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