Pipeline Accident Brief - Natural Gas Service Line Break and Subsequent Explosion and Fire

Bergenfield, New Jersey
December 13, 2005

NTSB Number: PAB-07-01
Adopted May 1, 2007
PDF

The Accident

On December 13, 2005, at 9:26 a.m., an apartment building exploded in Bergenfield, New Jersey, after natural gas migrated into the building from a damaged pipeline. Investigators found a break in an underground 1 1/4-inch steel natural gas distribution service line that was operating at 11 1/2 pounds per square inch, gauge. The break occurred at an underground threaded tee connection downstream from where excavators were removing an oil tank that was buried under the asphalt parking lot adjacent to the building. The break occurred, under the parking lot, about 7 feet 4 inches from the building's wall. Three residents of the apartment building were killed. Four residents and a tank removal worker were injured and transported to hospitals. The property damage consisted of the apartment building, which was a complete loss. According to Bergen County tax records, the assessed value of the apartment building was $863,300.

JP Management, a real estate company that owned the apartment building, hired the American Tank Service Company (American Tank) to remove and replace the buried oil tank. On December 5, 2005, American Tank requested markouts of the utilities at 30 Elm Street through the New Jersey One Call System. On December 7, 2005, a Public Service Electric and Gas Company (PSE&G) street inspector went to the site and marked the location of the buried gas service line to the building. The marked location showed that the service line ran under the parking lot and about parallel to the building's wall. At a point downstream of the excavation area, the pipeline turned 90° toward the building.

About 8:30 a.m. on Monday, December 12, the American Tank crew arrived at the site, saw the gas and water utility markouts, and began excavating in the asphalt parking lot that was adjacent to the building. The work contract indicated that the tank capacity was 2,000 gallons. According to the American Tank foreman, when the excavation was about 30 inches deep, the top of the tank was exposed. At this time, the crew realized that the tank was a 5,000-gallon tank rather than a 2,000-gallon tank. Because the larger tank was wider, longer, and heavier than expected, and thus closer to the natural gas service line, the excavation crew had concerns about its safe removal. In an interview, one of the crewmembers stated, "[At the time] I said our concern is once we move the tank or roll it over, to roll it and take it out, it may undermine the gas line." An American Tank vice president went to the site to verify that it was a larger tank and to reassess its removal. He arranged for his office staff to call New Jersey One Call for a second markout of the utilities. The PSE&G inspector arrived at the apartment building about 11:14 a.m. and re-marked the gas service line. He made a slight change to the original marking where the gas line entered the building.

The American Tank foreman told investigators that on December 12 he asked the PSE&G inspector whether the gas line could be shut off while they excavated. This request was a precaution to prevent the release of gas if the line was damaged during the tank removal. The PSE&G inspector told investigators he stated to the American Tank foreman that because it was wintertime the gas could not be shut off. However, the PSE&G inspector said that he would ask his supervisor. When the supervisor told the inspector that turning off the natural gas to the building would not be possible, the inspector informed the American Tank foreman. According to the PSE&G, shutting off the gas to the building without making prior arrangements with the PSE&G and the building's owner would have created a health risk to the residents by leaving them without gas for heat, hot water, and cooking.

The American Tank foreman and assistant manager said during postaccident interviews that, based on their examination of the worksite after the initial excavation, they thought the excavation was stable and secure, and the excavation wall was far enough from the pipe to be safe. However, the American Tank crew did not evaluate the soil at the walls of the ditch for stability.

The excavation crew exposed a portion of the gas pipeline by excavating with hand shovels to confirm the service line's location. The excavation was done by digging into the eastern trench wall, near the gas pipeline and the building, while standing in the trench. The PSE&G street inspector who had marked the pipeline told Safety Board investigators that he was on site when the service line was first uncovered. The service line was partially exposed in two locations that were each about 1 foot long. The service line was buried about 30 to 36 inches and was about 2 feet from the extended eastern edge of the trench. To excavate the 5,000-gallon tank, the crew had to open a trench that was about 24 feet long, which was considerably larger than originally planned.

The PSE&G inspector determined that the pipeline was a PSE&G gas pipeline and that it was accurately marked. According to the inspector, he reminded the American Tank crewmembers of their obligation to protect the gas pipe from damage by supporting the pipe against an immovable object, such as the building, or shoring the trench. The PSE&G inspector did not remain on the job to ensure that the pipeline was adequately protected. In addition, he did not attempt to test the curb valve to ensure it could be rapidly closed if the pipeline was broken. The inspector gave the American Tank foreman his business card and asked him to call if he needed assistance or had any questions. The inspector departed the site at 11:47 a.m. According to the American Tank foreman, the trench was not shored and was about 4 to 5 feet deep at the end of the first day.

The American Tank crew (assistant manager, foreman, and two crewmembers) arrived about 8:30 a.m. on Tuesday, December 13, 2005, to continue work on the excavation. The American Tank crewmembers told Safety Board investigators that they did not start any of the excavation equipment or expand the excavation on December 13, the day of the accident. When they first arrived, they saw that the ground surrounding the pipeline had collapsed and fallen from underneath portions of the asphalt parking lot along the eastern wall of the trench. The crewmembers said that they tied one end of a rope to the gas pipeline and the other end to the oil tank vent pipe at the building wall in an effort to help support the pipeline. The American Tank crew also placed a pump into the trench and was removing some of the water that had accumulated when some crewmembers reported hearing a "popping" sound and two crewmembers smelled natural gas. Shortly afterward, the other two crewmembers smelled natural gas.

From across the street, a local business owner saw the American Tank crew working at 30 Elm Street. He said that he saw water flowing down the road and when he went across the street to where the American Tank crew was working, he smelled natural gas. The business owner said that he would call the police for them. He called the Bergenfield Police Department at 8:49 a.m. and reported a gas leak. His call was the only one that the Bergenfield Police Department received about the incident before the explosion. An apartment resident later told Safety Board investigators that she also had smelled natural gas, but had not called the police department, the fire department, or the PSE&G. The American Tank foreman called the PSE&G at 8:54 a.m. and reported that the ground had collapsed and the service line was broken.

According to the Bergenfield Police Department dispatch logs, at 8:52 a.m., the Bergenfield Fire Department's chief, a fire official, and an engine company responded to an initial notification of a gas leak. Two Bergenfield Police Department police officers were also dispatched. A Bergenfield police officer directed traffic away from the area. After arriving on scene about 8:54 a.m., the fire chief asked the police dispatchers to notify the PSE&G. At 8:58 a.m., police dispatchers notified the PSE&G of the incident. The fire chief told Safety Board investigators that he had not observed any signs of a leak at the trench (that is, smelling gas, hearing a "hissing" sound, or seeing bubbling of water in the trench). The fire official said that he did not smell gas at the scene. No one from the Bergenfield Fire Department checked the apartment building for the presence of natural gas. The fire department did not attempt to evacuate the building before the explosion.

The Bergenfield fire chief said that the American Tank crew warned him, before the explosion, about the soil giving way in the trench and to be careful while walking near the trench. The fire chief also said that he looked into the trench and could see that the soil beneath the asphalt on the east side of the trench had fallen into the trench.

About 9:22 a.m., a PSE&G service technician arrived on scene. The technician attempted to close the curb valve to shut off the gas, but he was unable to apply enough force to close it. In a postaccident interview, the service technician said that as he approached the building to investigate the gas leak, an American Tank crewmember told him to not get too close to the trench because it had already collapsed. The service technician said that he had seen a piece of asphalt that had fallen into the trench. The service technician, using a portable gas detector, detected a positive gas reading just inside the boiler room doorway of the apartment building. He started moving away from the building as it exploded at 9:26 a.m.

The police and fire departments, American Tank, and the PSE&G started rescue actions. The fire departments started firefighting. About 10:00 a.m., a PSE&G street crew was able to shut off the gas to the service line by closing the curb valve.

Probable Cause

The National Transportation Safety Board determines that the probable cause of the December 13, 2005, natural gas explosion and fire in Bergenfield, New Jersey, was the failure of the American Tank Service Company to adequately protect the natural gas service line from shifting soil during excavation, which resulted in damage to the service line and the release and migration of natural gas into the apartment building. Contributing to the accident was the failure of the Public Service Electric and Gas Company to conduct effective oversight of the excavation activities adjacent to the gas service line and to be prepared to promptly shut off the flow of natural gas after the service line was damaged. Contributing to the casualties in the accident was the failure of the Bergenfield Fire Department to evacuate the apartment building despite the strong evidence of a natural gas leak and the potential for gas to migrate into the building.

Recommendations

As a result of its investigation of the Bergenfield, New Jersey, pipeline accident, the National Transportation Safety Board made the safety recommendations listed below. For more information about these recommendations, see the safety recommendation letters to the recipients.

To the Pipeline and Hazardous Materials Safety Administration:

Provide a summary of the lessons learned from the Bergenfield, New Jersey, accident to recipients of emergency planning and response grants. (P-07-1)

To the New Jersey Department of Community Affairs:

Establish a requirement that all career and volunteer firefighters receive recurrent training on natural gas safety and incident response. (P-07-2)

To the Borough of Bergenfield:

Establish and implement written operating procedures for responding to natural gas incidents and emergencies. (P-07-3)

To the American Tank Service Company:

Establish and implement written procedures for safe excavation near pipelines, and provide initial and recurrent training on these procedures to employees. (P-07-4)

To the Public Service Electric and Gas Company:

Modify your excavation damage prevention program and emergency plan to require site-specific risk assessments of excavators' plans, and implement procedures to effectively manage the risk, such as increased surveillance of excavator actions to protect the pipeline and ensuring that gas shut-off valves are tested so that they can be closed promptly if the pipeline is damaged. (P-07-5)

To the International Association of Fire Chiefs:

Notify your members of the circumstances surrounding the December 13, 2005, accident in Bergenfield, New Jersey, and urge them to establish and implement procedures for emergency responders to rapidly assess situations involving natural gas leaks and to determine whether prompt evacuations are warranted. (P-07-6)