{"operation":"document","citation":"DCA17FP002","title":"Gasoline Transmission Pipeline Explosion/Fire","source_type":"incident","agency":"National Transportation Safety Board","status":"current","official":true,"published_on":"2021-05-18","effective_on":"2016-10-31","summary":"Accident. in Helena, AL, USA. on 2016-10-31. Colonial Pipeline. Leak/explosion/fire","machine_formats":{"json":"https://regulus.evalyn.ai/document/ntsb-case-dca17fp002.json","markdown":"https://regulus.evalyn.ai/document/ntsb-case-dca17fp002.md"},"app_url":"https://regulus.evalyn.ai/document/ntsb-case-dca17fp002","source_url":"https://www.ntsb.gov/investigations/Pages/DCA17FP002.aspx","body":"NTSB investigation DCA17FP002.\n\nEvent Type: Accident\n\nEvent Date: 2016-10-31\n\nEvent City: Helena\n\nEvent State Or Region: AL\n\nEvent Country: USA\n\nPipeline Operator: Colonial Pipeline\n\nAccident Type: Leak/explosion/fire\n\nCompletion Status: Completed\n\nReport Number: PAB1904\n\nReport Date: 2019-12-10\n\nProbable cause: The National Transportation Safety Board determines that the probable cause of the explosion was the excavation crew’s inadequate planning, coordination, and communication during the excavation and failure to adhere to company policy requiring hand excavation if closer than 2 feet from the top or bottom of the pipeline until the pipeline has been exposed, which allowed the track-hoe to damage the pipeline.\n\nTier1Name: System operating, changing flow/pressure\n\nTier2Name: Fire (post-release)\n\nTier1Name: System shutdown\n\nTier2Name: Emergency shutoff\n\nTier1Name: Emergency response\n\nTier2Name: Fire (post-release)\n\nTier1Name: System operating\n\nTier2Name: Product leak/release\n\nTier1Name: System operating\n\nTier2Name: External/third-party damage\n\nFinding Tier1Name: Organizational\n\nFinding Tier2Name: Management\n\nFinding Tier3Name: Communication (organizational)\n\nFinding Modifier Name: Inspection organization\n\nFinding Report Text: Organizational - Management - Communication (organizational) - Inspection organization\n\nFinding Tier1Name: Organizational\n\nFinding Tier2Name: Management\n\nFinding Tier3Name: Policy/procedure\n\nFinding Modifier Name: Inspection organization\n\nFinding Report Text: Organizational - Management - Policy/procedure - Inspection organization\n\nFinding Tier1Name: Personnel\n\nFinding Tier2Name: Action/decision\n\nFinding Tier3Name: Information processing/decision making\n\nFinding Modifier Name: Equipment/vehicle operator\n\nFinding Report Text: Personnel - Action/decision - Information processing/decision making - Equipment/vehicle operator\n\nFinding Tier1Name: Personnel\n\nFinding Tier2Name: Task performance\n\nFinding Tier3Name: Communication (personnel)\n\nFinding Modifier Name: Non-pipeline equipment personnel\n\nFinding Report Text: Personnel - Task performance - Communication (personnel) - Non-pipeline equipment personnel\n\nOfficial NTSB investigation data. NTSB findings determine probable cause and make safety recommendations; they do not adjudicate civil liability or regulatory violations.\n\nWhat Happened\nOn October 31, 2016, at 2:47 p.m., local time, while excavating, a contractor damaged the Colonial Pipeline Company's (Colonial) 36-inch diameter refined liquid petroleum transmission pipeline, known as Line 1, near Helena, Alabama. The damage resulted in a release of gasoline from the pipeline, which ignited and burned for several days. Two excavation crew workers died, and four other workers were injured. The photographs in Figures 1 and 2 show the equipment and environmental damage that resulted from the fire. Figure 1 is a ground-level view of the ongoing fire and equipment damage that occurred from the gasoline release. Figure 2 is an aerial view of the excavated Line 1 pipeline and accident-related environmental damage taken during the postaccident investigation.\n\nWhat We Found\nWe determined that the probable cause of the explosion was the excavation crew’s inadequate planning, coordination, and communication during the excavation and failure to adhere to company policy requiring hand excavation if closer than 2 feet from the top or bottom of the pipeline until the pipeline has been exposed, which allowed the track-hoe to damage the pipeline.\n\nPAB-19-04\n<<<PAGE 1>>>\n\nNational Transportation Safety Board\nPipeline Accident Brief\nGasoline Transmission Pipeline Explosion/Fire\nHelena, Alabama\nOctober 31, 2016\nThe Accident\nOn October 31, 2016, at 2:47 p.m., local time, while excavating, a contractor damaged the\nColonial Pipeline Company’s (Colonial) 36-inch diameter refined liquid petroleum transmission\npipeline, known as Line 1, near Helena, Alabama. The damage resulted in a release of gasoline\nfrom the pipeline, which ignited and burned for several days. Two excavation crew workers died,\nand four other workers were injured. The photographs in Figures 1 and 2 show the equipment and\nenvironmental damage that resulted from the fire. Figure 1 is a ground-level view of the ongoing\nfire and equipment damage that occurred from the gasoline release. Figure 2 is an aerial view of\nthe excavated Line 1 pipeline and accident-related environmental damage taken during the\npostaccident investigation.\n1\nFigure 1. Ground-level view of active fire. (Source first responders.)\n1 For more detailed information about this accident investigation, see the the public docket at\nhttps://www.ntsb.gov/investigations/dms.html and search for accident number DCA17FP002.\n60057 NTSB/PAB-19/04\n\n<<<PAGE 2>>>\n\nHelena Pipeline Explosion/Fire\nFigure 2. Aerial view of environmental damage. (Source: ESI, a Colonial\ntechnical contractor.)\nBackground\nColonial is an interstate common carrier that delivers refined liquid petroleum products,\nincluding gasoline, kerosene, home-heating oil, and jet fuel, throughout the southeastern, mid-\nAtlantic, and northeastern United States. Colonial’s pipeline system extends from Houston, Texas,\nto Linden, New Jersey, crossing 13 states.2 The company transports about 2.4 million barrels of\nrefined products per day. There were two Colonial contractors involved in this accident. One\ncontractor was L.E. Bell Construction Company, Inc. (L.E. Bell), which performed excavation and\nmaintenance activities at the accident site.3 The second contractor was Superior Land Designs,\nLLC (Superior Land Designs), which performed project inspection services at the accident site.\n4\nLine 1 Pipeline\nThe accident occurred on Colonial’s Line 1, which extends from Houston, Texas, to\nGreensboro, North Carolina. When the accident occurred, Line 1 was transporting gasoline\neastward at a maximum flow rate of 58,000 barrels per hour, with a maximum operating pressure\n2 For further information, see the Colonial Pipeline website at http://www.colpipe.com/.\n3 For further information, see the L.E. Bell Construction Company Pipeline Stations and Terminals website at\nhttps://www.lebellconstruction.com/.\n4 For further information, see the Superior Land Designs website at https://www.superiorlanddesigns.com/.\n2\n\n<<<PAGE 3>>>\n\nHelena Pipeline Explosion/Fire\nat the accident site of 539 pounds per square inch, gauge. Line 1 at the accident site was a 36-inch\ndiameter pipe with a 0.281-inch wall thickness. The pipe was manufactured in 1960 by National\nTube, using double submerged arc welding to comply with American Petroleum Institute (API) 5L\nX52 grade pipe specification.\nColonial uses THREAD-O-RING (TOR) fittings welded to the pipe for maintenance work.\n(See figure 3.) TORs consist of a short length of pipe that contains mechanical components such\nas a pipe cap, an O-ring, and a pipe plug. The outward end is threaded for the attachment of a hose\nline, which can be used during field maintenance or testing (nitrogen injection/pressure testing of\nthe pipeline). The TOR fittings at the accident site were fabricated from NPS 2 pipe and were about\n5 inches long.\n5 There were four TOR fittings positioned along the top of the Line 1 pipeline at the\naccident site, spaced about 20 inches apart.\n5 Nominal Pipe Size (NPS) is a North American standard for specifying the size of pipe in nominal or\ndimensionless units for the diameter of the hole. For example, NPS 2 pipe has a 2.375-inch outside diameter. Also see\nAmerican Society of Mechanical Engineers B36.10M – 2018: Welded and Seamless Wrought Steel Pipe, October\n2018, for other pipe sizes.\n3\n\n<<<PAGE 4>>>\n\nHelena Pipeline Explosion/Fire\nFigure 3. Postaccident Illustration of TORs on Line 1 at the accident site. (Source: Colonial.)\n4\n\n<<<PAGE 5>>>\n\nHelena Pipeline Explosion/Fire\nPurpose of Excavation\nThe accident occurred near milepost 573.7, which was 306 feet northeast of River Road\n(County Road 251).\n6 Colonial refers to this location as the CR-251 jobsite. The right-of-way in\nthis area had a slight downhill slope to the southwest, which is in the direction of River Road. The\ntop of the Line 1 pipeline was buried with a depth of cover of about 24 inches in this area. The soil\nwas dry and rocky. According to the Colonial project manager, the geology did not present any\nsignificant challenges for the excavation work.\nAt the time of the accident, the excavation being performed was to expose a series of TOR\nfittings on Line 1 in preparation for upcoming maintenance work to inject nitrogen into Line 1\nduring the removal of a temporary bypass pipe used to repair a previous leak.7 The Colonial project\nmanager indicated that, by Colonial pipeline documentation alone, they were unable to confirm\nthe number of TORs on that segment of Line 1 (at the accident location) and that the number of\nTORs could only be verified by excavating the pipe.\n8 The excavation would also permit the\ninstallation of additional TORs for nitrogen injection if they were deemed necessary.\nThere were two concrete slabs positioned over the TORs on Line 1 at the CR-251 accident\nsite. The concrete slabs each measured 3 feet wide and 4 feet long, and they were situated in an\nend-to-end orientation (the 3-foot end of one slab abutted the 3-foot end of the other slab) so that\nthe slabs extended for 8 feet above the pipeline. The concrete slabs are intended to protect the\npipeline from unintended strikes during excavation work.\nAccording to National Transportation Safety Board (NTSB) interviews of L.E. Bell and\nColonial personnel, neither the L.E. Bell crew nor Colonial had knowledge of the two concrete\nslabs above the TOR fittings. There was no documentation available that indicated the dimensions,\ndepth, or position of the concrete slabs. The alignment sheets available to the work crew did not\nindicate the concrete pads over the TOR fittings and indicated only three of the four TOR fittings.\nAlthough the depiction of appurtenances such as TOR fittings was required at the time of the\naccident, there was no requirement that the concrete pads be indicated on the alignment sheets.\nThe Investigation\nAbout 2:15 p.m. on October 31, 2016, the L.E. Bell excavation crew arrived at the River\nRoad jobsite to excavate soil from above the pipe to allow access to the TOR fittings. As part of\nthis process, the L.E. Bell crew also had to remove any known nonsoil materials such as concrete\nslabs. The Superior Land Designs project inspector arrived at the River Road site about 2:30 p.m.\nAccording to the Superior Land Designs project inspector, seven L.E. Bell crewmembers were at\n6 Milepost references in a pipeline system refer to the linear distance, in miles, along the length of the pipeline,\nrelative to a designated origin point. Here the Colonial Line 1 origin point is located in Houston, Texas (to the west\nof the accident site).\n7 The previous leak on Line 1 occurred September 9, 2016, at a location about 5.5 miles downstream (northeast)\nof the accident site.\n8 In-line inspection data confirmed the presence of four branch connections; three of the TOR fittings had been\npreviously located. This data, as well as the alignment sheets, can be found in the public docket.\n5\n\n<<<PAGE 6>>>\n\nHelena Pipeline Explosion/Fire\nthe CR-251 site, including two spotters, a track-hoe operator, a superintendent, and a foreman.9\nThe Superior Land Designs project inspector told NTSB investigators that he had mentioned to\nthe L.E. Bell crew that the excavation site likely would have some protections for the TORs. The\nL.E. Bell superintendent represented in an NTSB interview that the presence of concrete slabs was\ninfrequent but possible.\nThe Superior Land Designs project inspector told NTSB investigators that he was informed\nby the L.E. Bell foreman about 2:35 p.m. that two of the L.E. Bell crewmembers had located Line\n1 at the River Road excavation site using a line locator and probing. The L.E. Bell foreman stated\nthat when Line 1 was located with the electronic line locator, the locator indicated that the center\nof the pipe was at a depth of about 3.5 feet. According to the Superior Land Designs project\ninspector, the L.E. Bell crew probed, located, and confirmed that the depth of Line 1 was the same\n(3 1/2 feet) as the line finder reading before excavation activities were initiated and that the L.E.\nBell crew had hand probed both sides of Line 1 before undertaking any excavation work.\nHowever, according to one of the two spotters, the track-hoe operator instructed him to\nprobe for the pipe where the orange ground markings identifying the pipe location were located.\nThe spotter also told NTSB that he could only get the probe down about 3 inches into the ground,\nwhich was contrary to what the Superior Land Designs project inspector stated, and accordingly\nhe could not confirm the depth of the pipe. The spotter stated that he tried to hammer the probe\ndown into the ground, but it “jumped back” because, based on his experience, he assumed that the\nprobe was hitting rocky material. In the industry, the typical next step would have been for another\nemployee to hold the probe at its bottom and for the spotter to either hammer the probe or,\nalternatively, move incrementally 2 inches away and reattempt probing under direction of the\nSuperior Land Designs project inspector. In addition, the spotter told NTSB that neither he nor\nanyone else performed additional probing prior to the accident.\nThe spotter told NTSB investigators that after he was unable to insert the probe more than\n3 inches into the ground; the track-hoe operator informed him that he was going to “clean up” first,\nby scratching the surface of the ground with the teeth of the track-hoe bucket. The purpose of the\nscratching was to remove the rock from the excavation area so that the probe could be properly\ninserted. The spotter also said that the Superior Land Designs project inspector remained silent\nwhile the scratching occurred.\nThe Superior Land Designs project inspector told NTSB that, about 2:40 p.m., the\ntrack-hoe operator gently scratched the ground with the track-hoe bucket teeth to loosen the\nhardened earth. The spotter described in an NTSB interview that the track-hoe operator’s pace of\nexcavation was faster than the work performed at another jobsite earlier that day and mentioned\nthat the excavation proceeded quickly.\nThe spotter stated in an NTSB interview that during the scratching process, the track-hoe\noperator was scratching directly over the pipe and that he visually signaled to the track-hoe\noperator that he was prepared to use the probe rod to locate the depth of the pipeline. The track-hoe\noperator did not allow him to probe. Also, the spotter said that on the fourth swipe the track-hoe\n9 A spotter is an employee who assists the operator in maneuvering equipment into position to prevent injuries or\nproperty damage.\n6\n\n<<<PAGE 7>>>\n\nHelena Pipeline Explosion/Fire\nbucket scratched what he believed to be a rock, but the bucket did not pick up any rocks. The\nspotter said the track-hoe operator then made a fifth swipe. At that point, the TOR fitting was\nimpacted, allowing gasoline to be released. During his interview, the spotter told NTSB\ninvestigators that he had not witnessed site work where the dirt over the pipeline has been\nexcavated before probing.\nAdditionally, the spotter estimated that after the final swipe, the track-hoe operator had dug\ndown a total depth of between 18 inches and 2 feet. Colonial personnel, during postaccident\nexamination, determined the top of the TORs to be 19 inches below grade, and the top of the\npipeline was 2 feet below grade.10 The spotter indicated that he did not hear the Superior Land\nDesigns project inspector say anything while the digs occurred. The spotter also stated that if\nColonial inspectors had been on-site, they would not have allowed mechanical excavation with the\ntrack-hoe excavator directly over the pipe.\nColonial’s Maintenance Procedure for Excavation and Backfill, CM-102, Revision 5,\nJanuary 30, 2015, states that hand excavation is required for the following conditions:\n• Excavation closer than 2 feet from top or bottom of pipeline until pipeline has\nbeen exposed.\n• Excavation closer than 2 feet from sides of pipeline until pipeline has been\nexposed.\n• Excavation closer than 1 foot from top or sides after pipeline has been exposed.\nThis means that after the pipe has been exposed, no mechanical excavation is\npermitted within 1 foot around the pipe.\n• Complex excavation involving tight quarters.\nAt 2:47 p.m., according to the Superior Land Designs project inspector, he heard what he\nthought at the time was the bucket of the track-hoe scratching rock on the third scratch of the\ntrack-hoe bucket and then “a wall of gasoline” struck him in the face, spraying from the excavation\nsite. He also stated that upon seeing the released gasoline, he was concerned that a fire would start.\nHe stated that he screamed at the L.E. Bell crewmembers to run, and he turned and ran toward the\nnearby wooded area. The L.E. Bell superintendent told NTSB investigators that he saw the\ntrack-hoe operator walking away from the spraying gasoline, but then he saw him turn around and\nwalk back toward the spray when the fire ignited. The L.E. Bell superintendent told NTSB\ninvestigators that he saw sparks close to a nearby power line just prior to ignition. There were also\nseveral internal combustion engines operating at the time of the fire ignition.\nDuring the investigation of this accident, an area of the accident site was excavated by\nhand, which exposed a segment of the pipeline and the four TOR fittings that were attached to the\ntop surface of the pipe. The examination revealed that one of the TOR fittings had been damaged\n10 Measurements were made in the field after soil levels may have been disturbed; thus, dimensions may differ by\na few inches as compared to the actual dimensions at the time of the accident.\n7\n\n<<<PAGE 8>>>\n\nHelena Pipeline Explosion/Fire\nin the accident. Figure 4 shows a close-up view of the base of the damaged TOR fitting and the\nbreach in the pipe at the point of the TOR attachment to the pipe surface.\nFigure 4. Close-up photo of base of damaged TOR fitting and breach in\npipe at point of TOR attachment to pipe. (Source: Colonial.)\nPostaccident Actions\nFollowing the accident, Colonial and L.E. Bell took action to improve the safety of their\nwork activities, as summarized below.\nColonial\n• Executed a safety stand-down to review existing policies and procedures, including the\nExcavation and Backfill Procedure, CM-102.\n• Implemented a safety management system (SMS) based on the American National\nStandards Institute/American Petroleum Institue (ANSI/API) Recommended Practice\n1173 and created the full-time positions of manager of SMS, vice president of\noperations services, and chief risk officer, who oversees SMS. 11\n• Implemented an annual review of procedures, including excavation and backfill\nprocedures, encompassing review of CM-102 by district project leaders and\n11 For further information see ANSI/API Recommended Practice 1173 Pipeline Safety Management Systems,\nFirst edition, July 2015, API, https://www.api.org/~/media/files/publications/whats%20new/1173_e1%20pa.pdf.\n8\n\n<<<PAGE 9>>>\n\nHelena Pipeline Explosion/Fire\nmanagement personnel, where formal revisions, if any, are published and reviewed\nannually with the projects team (including project managers and inspectors) during\ntheir annual training.\n• Implemented contract inspector operator qualification, in which, as a new requirement,\ncontract inspectors must now be operator qualified for any covered task they inspect,\nand general contractor operator qualification requirements are unchanged.\n• Implemented credential and qualification verifications in which contract inspector\ncredentials/qualifications must be verified prior to assignment and periodically\nthereafter.\n• Improved contractor communications by creating a website as the primary source for\nColonial communications to contractors.\n• Colonial’s Health and Safety Council developed a field visits brochure to provide\ninsight for employees preparing to visit the field, with a reference guide issued to each\nnew hire, corporate office staff members, and external visitors who tour facilities and\njobsites.\n• Increased the number of safety specialists who perform random safety audits and\nconduct behavior-based safety observations at jobsites.\n• Instituted safety calls and meetings, where the company conducts monthly safety calls\nwith contractors and convenes annual face-to-face safety meetings with contractors.\nL.E. Bell\n• Implemented SMS, which captured the elements of the ANSI/API 1173.\n• Examined the company’s policies, procedures, and practices applicable to its overall\noperations and the specific work being performed at the time of the accident. The\ncompany concentrated on (1) refocused annual training and enhanced supervisor\ntraining and (2) field training enhancements and additional management presence in\nthe field.\n• Refocused annual training and enhanced supervisor training, which emphasizes its\nstop-work authority policy, emergency action planning, the contents of its excavation\nand back-fill policy and procedure, and abnormal operating conditions. The enhanced\nsupervisory training addresses hazard recognition and elimination, leadership,\naccident/incident/near-miss investigation, and field-safety auditing.\n• Increased field job aides and additional safety and leadership presence in the field,\nwhich further augmented and ingrained the company’s performance-based classroom\nand computer-based training throughout the year with several improvements to its job\nsite planning, assessment, and enforcement, in which it modified its job safety analysis\n9\n\n<<<PAGE 10>>>\n\nHelena Pipeline Explosion/Fire\nprocedure (requiring a new one whenever there is a change in (1) job location, (2) scope\nof work, (3) job task, or (4) a new potential hazard is identified).\n• Developed several job aides, checklists, and visual tools (safe work cards for\nsupervisors to use on every job) for use in the field to serve as a daily reminder for\nemployees to assess the job and potential hazards before and during their work or when\nchanges occur in the job location or scope of work or a new potential hazard arises.\nProbable Cause\nThe National Transportation Safety Board determines that the probable cause of the\nexplosion was the excavation crew’s inadequate planning, coordination, and communication\nduring the excavation and failure to adhere to company policy requiring hand excavation if closer\nthan 2 feet from the top or bottom of the pipeline until the pipeline has been exposed, which\nallowed the track-hoe to damage the pipeline.\nFor more details about this accident, visit www.ntsb.gov/investigations/dms.html and\nsearch for NTSB accident identification number DCA17FP002.\nReport Date: December 10, 2019\nThe NTSB has authority to investigate and establish the facts, circumstances, and cause or probable\ncause of a pipeline accident in which there is a fatality or substantial property damage, or that\ninvolves a passenger train. (Title 49 United States Code (USC) Section 1131 – General authority)\nThe NTSB does not assign fault or blame for an accident or incident; rather, as specified by NTSB\nregulation, “accident/incident investigations are fact-finding proceedings with no formal issues and\nno adverse parties . . . and are not conducted for the purpose of determining the rights or liabilities\nof any person.” Title 49 Code of Federal Regulations, Section 831.4. Assignment of fault or legal\nliability is not relevant to the NTSB’s statutory mission to improve transportation safety by\ninvestigating accidents and incidents and issuing safety recommendations. In addition, statutory\nlanguage prohibits the admission into evidence or use of any part of an NTSB report related to an\naccident in a civil action for damages resulting from a matter mentioned in the report. 49 USC,\nSection 1154(b).\n10","truncated":false,"body_characters":24059}