{"operation":"document","citation":"DCA03MP004","title":"Excavation Damage to Natural Gas Distribution Line Resulting in Explosion and Fire","source_type":"incident","agency":"National Transportation Safety Board","status":"current","official":true,"published_on":"2026-01-30","effective_on":"2003-07-02","summary":"Accident. in WILMINGTON, DE, USA. on 2003-07-02. Conectiv Power Delivery. Leak/explosion/fire","machine_formats":{"json":"https://regulus.evalyn.ai/document/ntsb-case-dca03mp004.json","markdown":"https://regulus.evalyn.ai/document/ntsb-case-dca03mp004.md"},"app_url":"https://regulus.evalyn.ai/document/ntsb-case-dca03mp004","source_url":"https://www.ntsb.gov/investigations/Pages/DCA03MP004.aspx","body":"NTSB investigation DCA03MP004.\n\nEvent Type: Accident\n\nEvent Date: 2003-07-02\n\nEvent City: WILMINGTON\n\nEvent State Or Region: DE\n\nEvent Country: USA\n\nPipeline Operator: Conectiv Power Delivery\n\nPipeline Type: Distribution\n\nAccident Type: Leak/explosion/fire\n\nCompletion Status: Completed\n\nReport Number: PAB-04-01\n\nProbable cause: The National Transportation Safety Board determines that the probable cause of the July 2, 2003, natural gas explosion in Wilmington, Delaware, was the failure of Quickform to verify that all underground facilities were marked within the proposed dig site before beginning excavation. Contributing to the accident was the failure of Tech Consultants and Quickform to effectively communicate about the project scope. Contributing to the severity of the accident was the failure of Quickform employees to immediately notify the utility owner and emergency authorities when they realized they had struck and pulled up a gas service line.\n\nTier1Name: System operating\n\nTier2Name: Fire/explosion (post-release)\n\nTier1Name: System operating\n\nTier2Name: Product leak/release\n\nTier1Name: Construction\n\nTier2Name: External/third-party damage\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\nFinding Tier1Name: Personnel\n\nFinding Tier2Name: Task performance\n\nFinding Tier3Name: Use of equip/info\n\nFinding Modifier Name: Non-pipeline equipment personnel\n\nFinding Report Text: Personnel - Task performance - Use of equip/info - Non-pipeline equipment personnel\n\nFinding Tier1Name: Pipeline\n\nFinding Tier2Name: Pipeline structure\n\nFinding Tier3Name: Pipe\n\nFinding Modifier Name: Damaged/degraded\n\nFinding Report Text: Pipeline - Pipeline structure - Pipe - Damaged/degraded\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 July 2, 2003, a contractor hired by the city of Wilmington, Delaware, to replace sidewalk and curbing dug into an unmarked natural gas service line with a backhoe. Although the service line did not leak where it was struck, the contact resulted in a break in the line inside the basement of 1816 West 3rd Street, where gas began to accumulate. A manager for the contractor said that he did not smell gas and therefore did not believe there was imminent danger and that he called an employee of the gas company and left a voice mail message. At approximately 1:44 p.m., an explosion destroyed two residences and damaged two others to the extent that they had to be demolished.\nOther nearby residences sustained some damage, and the residents on the block were displaced from their homes for about a week. Three contractor employees sustained serious injuries. Eleven additional people sustained minor injuries.\n\nWhat We Found\nWe determined that the probable cause of the July 2, 2003, natural gas explosion in Wilmington, Delaware, was the failure of Quickform to verify that all underground facilities were marked within the proposed dig site before beginning excavation. Contributing to the accident was the failure of Tech Consultants and Quickform to effectively communicate about the project scope.\nContributing to the severity of the accident was the failure of Quickform employees to immediately notify the utility owner and emergency authorities when they realized they had struck and pulled up a gas service line.\n\nPAB-04-01\n<<<PAGE 1>>>\n\nT\nL\nA\nN\nO\nI\nT\nA\nN\nR\nA\nN\nS\nP\nO\nR\nP\nL\nU\nR\nE\nU\nM\nU N\nI\nB\nU\nS\nT\nA\nT\nI\nO\nN\nS\nA\nF\nE\nT\nY\nB\nD\nO\nA\nR\nNational Transportation Safety Board\nWashington, D.C. 20594\nPipeline Accident Brief\nAccident No.: DCA-03-MP-004\nType of System: Natural gas distribution\nType of Accident: Rupture, explosion, and fire\nLocation: Wilmington, Delaware\nDate and Time: July 2, 2003, at 1:44 p.m., eastern daylight time\nOwner/Operator: Delmarva Power and Light Company doing\nbusiness as Conectiv Power Delivery\nFatalities: None\nInjuries: 14\nProperty Damage and Losses: $300,000\nMaterial Released: Natural gas\nPressure: 6 to 8 inches water column\nType of Failure: Excavation damage\nComponent Affected: 1-1/4 inch steel service line\nThe Accident\nOn July 2, 2003, a contractor hired by the city of Wilmington, Delaware, to\nreplace sidewalk and curbing dug into an unmarked natural gas service line with a\nbackhoe. (See figure 1.) Although the service line did not leak where it was struck, the\ncontact resulted in a break in the line inside the basement of 1816 West 3rd Street, where\ngas began to accumulate. A manager for the contractor said that he did not smell gas and\ntherefore did not believe there was imminent danger and that he called an employee of\nthe gas company and left a voice mail message. At approximately 1:44 p.m., an explosion\ndestroyed two residences and damaged two others to the extent that they had to be\ndemolished. Other nearby residences sustained some damage, and the residents on the\nblock were displaced from their homes for about a week. Three contractor employees\nsustained serious injuries. Eleven additional people sustained minor injuries.\nPreaccident Events\nQuickform Concrete Company was awarded a contract by the city of Wilmington\nto replace sidewalk and curbing at various locations specified in the contract. Tech\nConsultants was responsible for coordinating the sidewalk and curb improvements with\nNTSB/PAB-04/01 1\n\n<<<PAGE 2>>>\n\nQuickform for the city. The contract noted that street addresses would be used to indicate\ngeneral work locations but that the exact limits for the work would be marked out on site.\nFigure 1. Pulled natural gas service line.\nAfter the contract was issued, Tech Consultants received additional address\nlocations for this work. One such location was 1820 West 3rd Street. A Tech Consultants\nproject manager surveyed the work site and determined that sidewalk and curbing\nreplacement was needed in front of the residences at 1816, 1818, and 1820 West 3rd\nStreet. On April 10, 2003, a sketch was prepared by Tech Consultants showing the work\nto be done in front of the three addresses. On June 23, 2003, Tech Consultants issued a\nchange order to Quickform, which included the 1820 West 3rd Street address location in\na list of additional address locations. Tech Consultants did not provide the 1816 and 1818\naddresses or sketch to Quickform. According to Tech Consultants, the city asked Tech\nConsultants not to provide these sketches to contractors because the scope of work could\nchange and there was an expectation that the contractor would attend the work mark-out\non site.\nThe contract also required Quickform to have the underground utilities marked\nout before beginning excavation. On June 23, a Quickform manager called Miss Utility to\nhave underground utilities marked for 1820 West 3rd Street, but the manager\ninadvertently called in an incorrect address: 820 West 3rd Street.\nNTSB/PAB-04/01 2\n\n<<<PAGE 3>>>\n\nConectiv Power Delivery provided gas through its pipeline distribution network to\nthe residences on this block. On June 24, a Conectiv employee placed yellow paint marks\non the ground in front of 1818, 1820, and 1822 West 3rd Street to mark the location of its\nunderground service lines to those addresses. The Conectiv employee said that although\nthe Miss Utility information noted planned excavation at 820, he determined that the\nrequest for 820 was in error, and he proceeded to mark the correct 1820 address and the\nadditional addresses of 1818 and 1822 to provide a further safety margin.\nIn response to a June 30, 2003, request from the Quickform manager to mark out\nthe project scope, on July 1, a Tech Consultants inspector marked in white paint the\nsidewalk and curbing in front of 1816, 1818, and 1820 to indicate the scope of the work.\nThe Tech Consultants inspector said that the project scope is normally marked out just\ndays ahead of the work in order to (1) reduce the likelihood that those who live in the\narea will extend the marking in an attempt to get work done in front of their houses, and\n(2) limit the amount of open construction ongoing at any given time. Tech Consultants\nand Quickform said that about half the time, a Quickform representative would\naccompany the Tech Consultants inspector when locations were being marked; however,\non July 1, a Quickform representative did not accompany him. The inspector said that he\ndid not routinely look for signs that the locations of underground utilities had already\nbeen marked, and he could not recall noticing which addresses had been marked as he\nmarked the job out in front of 1816, 1818, and 1820 West 3rd Street.\nOn July 2, a Quickform crew arrived at the accident site location. The Quickform\nforeman said that he understood that the white paint marks defined the scope of work and\nthat as a result he understood that his crew was to replace sidewalk and curbing in front\nof 1816, 1818, and 1820. He also said that because he didn’t see any yellow paint\nmarkings in front of 1816, he believed that there was no underground gas line there and\nthat it was safe to excavate with a backhoe.\nOn July 2, a Quickform backhoe contacted and pulled up an unmarked 1-1/4 inch\nsteel service line serving 1816 West 3rd Street. Contractor employees estimated that the\ndamage to the service line occurred at about 1:30 p.m. The crew was not aware that the\naction of pulling the service line outside resulted in a break to the line inside the\nbasement at 1816 West 3rd Street. Natural gas then began to accumulate in the residence.\nThe Quickform crew said when they saw the damage, they stopped excavation activities\nand notified the Quickform manager when he arrived on site a few minutes after the\nservice line was contacted.\nThe line was not leaking outside,1 and the crewmembers and manager said that\nthey did not smell a gas odor coming from the pulled line itself; however, four of the five\ncrewmembers reported that they smelled a faint gas odor at other points along the block\nbefore the explosion. The Quickform manager called the Tech Consultants inspector to\nask for the phone number of a Conectiv engineer to report the damage; cell phone records\nshow that this call was placed at 1:31 p.m. And according to cell phone records, the\n1 Postaccident pressure tests established that the service line was not leaking outside.\nNTSB/PAB-04/01 3\n\n<<<PAGE 4>>>\n\nmanager placed a call at 1:34 p.m. to the Conectiv engineer’s phone, and the manager left\na voice mail message.\nA resident of 1816 West 3rd Street said that she smelled a strong odor in her\nhouse at about 1:00 p.m. or shortly thereafter. She and her two children left the house, but\nshe did not tell anyone about the odor. At 1:44 p.m., the explosion occurred. Eight other\nresidents who lived on the block told investigators that they smelled a gas odor before the\nexplosion. Except for Quickform’s voice mail to Conectiv, no calls were placed to\nConectiv or the fire department about the damaged line or a leak before the explosion.\nEmergency Response\nBeginning at 1:45 p.m., the Wilmington Police Department’s dispatcher received\nnumerous telephone calls reporting an explosion on West 3rd Street. The police\ndepartment responded to the site to evacuate residents, conduct crowd and traffic control,\nand provide security.\nAt 1:45 p.m., the Wilmington Fire Department initially dispatched two engine\ncompanies, a ladder company, and a battalion chief. At 1:48 p.m., the first responding\ncity ambulance arrived at the accident site. New Castle County Emergency Medical\nServices (EMS) received the initial dispatch and was en route to the scene at 1:49 p.m. At\n1:50 p.m., the first fire department units arrived at the site. At 1:53 p.m., the first EMS\nresponders arrived at the site. At 1:53 p.m., the deputy chief of operations for the fire\ndepartment arrived at the site and assumed incident command.\nPostaccident Excavation Procedures\nIn September 2003, Tech Consultants modified the contracts for sidewalk and\ncurb improvements to require the contractor to be present for marking out the project\nscope, and then to call Miss Utility to have the underground utilities marked out for the\nproject scope.\nSince the accident, Quickform has developed written safety procedures that\ninstruct employees to verify that underground utilities are marked before beginning\nexcavation and to call emergency numbers if a natural gas line is hit. The Quickform\nmanager advised that the company’s interpretation of a hit line includes a line that is\npulled.\nOccupational Safety and Health Administration\nThe U.S. Department of Labor’s Occupational Safety and Health Administration\n(OSHA) investigated this accident. Title 29 Code of Federal Regulations (CFR)\nNTSB/PAB-04/01 4\n\n<<<PAGE 5>>>\n\n1926.651 establishes excavation requirements designed to prevent damage to\nunderground utilities, including a requirement to establish the location of underground\ninstallations before opening an excavation. On December 3, 2003, OSHA issued a\ncitation and notification of penalty to Quickform for not contacting Miss Utility before\nexcavating in front of 1816 West 3rd Street.\nAs a result of its investigation of a natural gas pipeline accident in St. Cloud,\nMinnesota, on December 11, 1998,2 the Safety Board made the following safety\nrecommendation to OSHA:\nP-00-2\nRequire excavators to notify the pipeline operator immediately if their\nwork damages a pipeline and to call 911 or other local emergency\nresponse number immediately if the damage results in a release of natural\ngas or other hazardous substance or potentially endangers life, health, or\nproperty.\nIn response to this safety recommendation, on June 13, 2003, OSHA issued a\nSafety and Health Information Bulletin that advises contractors on the hazards of striking\nunderground gas lines during excavation work. The bulletin recommended informing the\npipeline operator immediately if the excavator causes damage to a pipeline and to\nimmediately contact emergency authorities if the damage results in a release of natural\ngas or other hazardous substances.\nCommon Ground Alliance Best Practices\nThe Common Ground Alliance provides a guide to underground utility damage\nprevention best practices in use throughout the United States. These best practices speak\nto the value of effective communication among those involved in excavation activities. A\nbest practice notes the value of premarking the excavation area before the one-call3 and\nbefore the locator arrives on site as a means of communicating where the excavation is to\noccur. A best practice advises that upon arrival at the excavation site, excavators should\nverify that the dig site matches the one-call request.\nAnother best practice, which came about in response to another safety\nrecommendation issued as a result of the Safety Board’s investigation of the St. Cloud,\nMinnesota, accident, states that excavators should notify the pipeline operator\nimmediately if their work damages a pipeline and to call 911 or other local emergency\n2 National Transportation Safety Board, Natural Gas Pipeline Rupture and Subsequent Explosion in St.\nCloud, Minnesota, December 11, 1998. Pipeline Accident Report NTSB/PAR-00/01 (Washington, D.C.:\nNTSB, 2000).\n3 The one-call system, the name of which varies from State to State, allows excavators, with a single\ncall, to notify all underground facility owners who are members of the one-call system of planned\nexcavation so the locations of the various facilities can be marked.\nNTSB/PAB-04/01 5\n\n<<<PAGE 6>>>\n\nresponse number immediately if the damage results in a release of natural gas or other\nhazardous substance or potentially endangers life, health, or property.4\nPublic Education\nIn September 2002, Conectiv included a natural gas informational insert in the\nutility bills of its natural gas customers. As part of its public education program, Conectiv\nmailed this type of insert to its natural gas customers approximately once per year. The\ninsert included advice to customers that if the odor was extremely strong to evacuate the\npremises and call Conectiv.\nTitle 49 CFR 192.616 requires that pipeline operators establish a continuing\neducation program to enable the public to recognize a gas pipeline emergency for the\npurpose of reporting it to the operator or appropriate public officials.\nThe Safety Board has long been concerned about the issue of pipeline public\neducation programs, including the content, distribution, and effectiveness of pipeline\noperators’ safety materials for both hazardous liquid and natural gas pipelines. As a result\nof its investigation of a liquid butane pipeline accident near Lively, Texas, on\nAugust 24, 1996,5 the Safety Board recommended that the Research and Special\nPrograms Administration (RSPA):\nP-98-38\nRevise 49 Code of Federal Regulations Part 195 to require that pipeline\noperators periodically evaluate the effectiveness of their public education\nprograms using scientific techniques.\nIn December 2003, the American Petroleum Institute published its Recommended\nPractice (RP) 1162 Public Awareness Programs for Pipeline Operators. This standard\ncalls for pipeline operators to periodically evaluate the effectiveness of their public\neducation programs. RSPA has advised the Safety Board that organizations representing\nessentially the entire gas and hazardous liquid pipeline industry have urged RSPA to\nincorporate RP 1162 into the pipeline safety regulations and that RSPA is committed to\nincorporating by reference RP 1162 into the pipeline safety regulation (49 CFR Parts 192\nand 195). As a result, the Safety Board, on November 21, 2003, classified Safety\nRecommendation P-98-38 “ClosedAcceptable Action.”\n4 Safety Recommendation P-00-1.\n5 National Transportation Safety Board, Pipeline Rupture, Liquid Butane Release and Fire, Lively,\nTexas, August 24, 1996. Pipeline Accident Report NTSB/PAR-98/02 (Washington, D.C.: NTSB, 1998).\nNTSB/PAB-04/01 6\n\n<<<PAGE 7>>>\n\nProbable Cause:\nThe National Transportation Safety Board determines that the probable cause of\nthe July 2, 2003, natural gas explosion in Wilmington, Delaware, was the failure of\nQuickform to verify that all underground facilities were marked within the proposed dig\nsite before beginning excavation. Contributing to the accident was the failure of Tech\nConsultants and Quickform to effectively communicate about the project scope.\nContributing to the severity of the accident was the failure of Quickform employees to\nimmediately notify the utility owner and emergency authorities when they realized they\nhad struck and pulled up a gas service line.\nAdopted: April 6, 2004\nNTSB/PAB-04/01 7","truncated":false,"body_characters":18799}