NTSB/PAB-04/01 1 

E PLURIBUS UNUM

NATIONAL TRA S PORTATIO

N

B OARD

SAFE T Y

N

National Transportation Safety Board 

Washington, D.C. 20594 

Pipeline Accident Brief

Accident No.: DCA-03-MP-004 

Type of System: Natural gas distribution 

Type of Accident: Rupture, explosion, and fire 

Location: Wilmington, Delaware 

Date and Time: July 2, 2003, at 1:44 p.m., eastern daylight time 

Owner/Operator: Delmarva Power and Light Company doing 

business as Conectiv Power Delivery 

Fatalities: None 

Injuries: 14 

Property Damage and Losses: $300,000 

Material Released: Natural gas 

Pressure: 6 to 8 inches water column 

Type of Failure: Excavation damage 

Component Affected: 1-1/4 inch steel service line 

The Accident 

On 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. (See figure 1.) 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. Other 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. 

Preaccident Events 

Quickform Concrete Company was awarded a contract by the city of Wilmington 

to replace sidewalk and curbing at various locations specified in the contract. Tech 

Consultants was responsible for coordinating the sidewalk and curb improvements with 
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Quickform for the city. The contract noted that street addresses would be used to indicate 

general work locations but that the exact limits for the work would be marked out on site. 

Figure 1. Pulled natural gas service line.

After the contract was issued, Tech Consultants received additional address 

locations for this work. One such location was 1820 West 3rd Street. A Tech Consultants 

project manager surveyed the work site and determined that sidewalk and curbing 

replacement was needed in front of the residences at 1816, 1818, and 1820 West 3rd 

Street. On April 10, 2003, a sketch was prepared by Tech Consultants showing the work 

to be done in front of the three addresses. On June 23, 2003, Tech Consultants issued a 

change order to Quickform, which included the 1820 West 3rd Street address location in 

a list of additional address locations. Tech Consultants did not provide the 1816 and 1818 

addresses or sketch to Quickform. According to Tech Consultants, the city asked Tech 

Consultants not to provide these sketches to contractors because the scope of work could 

change and there was an expectation that the contractor would attend the work mark-out 

on site. 

The contract also required Quickform to have the underground utilities marked 

out before beginning excavation. On June 23, a Quickform manager called Miss Utility to 

have underground utilities marked for 1820 West 3rd Street, but the manager 

inadvertently called in an incorrect address: 820 West 3rd Street. 
 NTSB/PAB-04/01 3 

Conectiv Power Delivery provided gas through its pipeline distribution network to 

the residences on this block. On June 24, a Conectiv employee placed yellow paint marks 

on the ground in front of 1818, 1820, and 1822 West 3rd Street to mark the location of its 

underground service lines to those addresses. The Conectiv employee said that although 

the Miss Utility information noted planned excavation at 820, he determined that the 

request for 820 was in error, and he proceeded to mark the correct 1820 address and the 

additional addresses of 1818 and 1822 to provide a further safety margin. 

In response to a June 30, 2003, request from the Quickform manager to mark out 

the project scope, on July 1, a Tech Consultants inspector marked in white paint the 

sidewalk and curbing in front of 1816, 1818, and 1820 to indicate the scope of the work. 

The Tech Consultants inspector said that the project scope is normally marked out just 

days ahead of the work in order to (1) reduce the likelihood that those who live in the 

area will extend the marking in an attempt to get work done in front of their houses, and 

(2) limit the amount of open construction ongoing at any given time. Tech Consultants 

and Quickform said that about half the time, a Quickform representative would 

accompany the Tech Consultants inspector when locations were being marked; however, 

on July 1, a Quickform representative did not accompany him. The inspector said that he 

did not routinely look for signs that the locations of underground utilities had already 

been marked, and he could not recall noticing which addresses had been marked as he 

marked the job out in front of 1816, 1818, and 1820 West 3rd Street. 

On July 2, a Quickform crew arrived at the accident site location. The Quickform 

foreman said that he understood that the white paint marks defined the scope of work and 

that as a result he understood that his crew was to replace sidewalk and curbing in front 

of 1816, 1818, and 1820. He also said that because he didn’t see any yellow paint 

markings in front of 1816, he believed that there was no underground gas line there and 

that it was safe to excavate with a backhoe. 

On July 2, a Quickform backhoe contacted and pulled up an unmarked 1-1/4 inch 

steel service line serving 1816 West 3rd Street. Contractor employees estimated that the 

damage to the service line occurred at about 1:30 p.m. The crew was not aware that the 

action of pulling the service line outside resulted in a break to the line inside the 

basement at 1816 West 3rd Street. Natural gas then began to accumulate in the residence. 

The Quickform crew said when they saw the damage, they stopped excavation activities 

and notified the Quickform manager when he arrived on site a few minutes after the 

service line was contacted. 

The line was not leaking outside,1

 and the crewmembers and manager said that 

they did not smell a gas odor coming from the pulled line itself; however, four of the five 

crewmembers reported that they smelled a faint gas odor at other points along the block 

before the explosion. The Quickform manager called the Tech Consultants inspector to 

ask for the phone number of a Conectiv engineer to report the damage; cell phone records 

show that this call was placed at 1:31 p.m. And according to cell phone records, the 

 

1

 Postaccident pressure tests established that the service line was not leaking outside. 
 NTSB/PAB-04/01 4 

manager placed a call at 1:34 p.m. to the Conectiv engineer’s phone, and the manager left 

a voice mail message. 

A resident of 1816 West 3rd Street said that she smelled a strong odor in her 

house at about 1:00 p.m. or shortly thereafter. She and her two children left the house, but 

she did not tell anyone about the odor. At 1:44 p.m., the explosion occurred. Eight other 

residents who lived on the block told investigators that they smelled a gas odor before the 

explosion. Except for Quickform’s voice mail to Conectiv, no calls were placed to 

Conectiv or the fire department about the damaged line or a leak before the explosion. 

Emergency Response 

Beginning at 1:45 p.m., the Wilmington Police Department’s dispatcher received 

numerous telephone calls reporting an explosion on West 3rd Street. The police 

department responded to the site to evacuate residents, conduct crowd and traffic control, 

and provide security. 

At 1:45 p.m., the Wilmington Fire Department initially dispatched two engine 

companies, a ladder company, and a battalion chief. At 1:48 p.m., the first responding 

city ambulance arrived at the accident site. New Castle County Emergency Medical 

Services (EMS) received the initial dispatch and was en route to the scene at 1:49 p.m. At 

1:50 p.m., the first fire department units arrived at the site. At 1:53 p.m., the first EMS 

responders arrived at the site. At 1:53 p.m., the deputy chief of operations for the fire 

department arrived at the site and assumed incident command. 

Postaccident Excavation Procedures 

In September 2003, Tech Consultants modified the contracts for sidewalk and 

curb improvements to require the contractor to be present for marking out the project 

scope, and then to call Miss Utility to have the underground utilities marked out for the 

project scope. 

Since the accident, Quickform has developed written safety procedures that 

instruct employees to verify that underground utilities are marked before beginning 

excavation and to call emergency numbers if a natural gas line is hit. The Quickform 

manager advised that the company’s interpretation of a hit line includes a line that is 

pulled. 

Occupational Safety and Health Administration 

The U.S. Department of Labor’s Occupational Safety and Health Administration 

(OSHA) investigated this accident. Title 29 Code of Federal Regulations (CFR) 
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1926.651 establishes excavation requirements designed to prevent damage to 

underground utilities, including a requirement to establish the location of underground 

installations before opening an excavation. On December 3, 2003, OSHA issued a 

citation and notification of penalty to Quickform for not contacting Miss Utility before 

excavating in front of 1816 West 3rd Street. 

As a result of its investigation of a natural gas pipeline accident in St. Cloud, 

Minnesota, on December 11, 1998,2

 the Safety Board made the following safety 

recommendation to OSHA: 

P-00-2

Require excavators to notify the pipeline operator immediately if their 

work damages a pipeline and to call 911 or other local emergency 

response number immediately if the damage results in a release of natural 

gas or other hazardous substance or potentially endangers life, health, or 

property. 

In response to this safety recommendation, on June 13, 2003, OSHA issued a 

Safety and Health Information Bulletin that advises contractors on the hazards of striking 

underground gas lines during excavation work. The bulletin recommended informing the 

pipeline operator immediately if the excavator causes damage to a pipeline and to 

immediately contact emergency authorities if the damage results in a release of natural 

gas or other hazardous substances. 

Common Ground Alliance Best Practices 

The Common Ground Alliance provides a guide to underground utility damage 

prevention best practices in use throughout the United States. These best practices speak 

to the value of effective communication among those involved in excavation activities. A 

best practice notes the value of premarking the excavation area before the one-call3 and 

before the locator arrives on site as a means of communicating where the excavation is to 

occur. A best practice advises that upon arrival at the excavation site, excavators should 

verify that the dig site matches the one-call request. 

Another best practice, which came about in response to another safety 

recommendation issued as a result of the Safety Board’s investigation of the St. Cloud, 

Minnesota, accident, states that excavators should notify the pipeline operator 

immediately if their work damages a pipeline and to call 911 or other local emergency 

 

2

 National Transportation Safety Board, Natural Gas Pipeline Rupture and Subsequent Explosion in St. 

Cloud, Minnesota, December 11, 1998. Pipeline Accident Report NTSB/PAR-00/01 (Washington, D.C.: 

NTSB, 2000). 

3

 The one-call system, the name of which varies from State to State, allows excavators, with a single 

call, to notify all underground facility owners who are members of the one-call system of planned 

excavation so the locations of the various facilities can be marked. 
 NTSB/PAB-04/01 6 

response number immediately if the damage results in a release of natural gas or other 

hazardous substance or potentially endangers life, health, or property.4

 

Public Education 

In September 2002, Conectiv included a natural gas informational insert in the 

utility bills of its natural gas customers. As part of its public education program, Conectiv 

mailed this type of insert to its natural gas customers approximately once per year. The 

insert included advice to customers that if the odor was extremely strong to evacuate the 

premises and call Conectiv. 

Title 49 CFR 192.616 requires that pipeline operators establish a continuing 

education program to enable the public to recognize a gas pipeline emergency for the 

purpose of reporting it to the operator or appropriate public officials. 

The Safety Board has long been concerned about the issue of pipeline public 

education programs, including the content, distribution, and effectiveness of pipeline 

operators’ safety materials for both hazardous liquid and natural gas pipelines. As a result 

of its investigation of a liquid butane pipeline accident near Lively, Texas, on 

August 24, 1996,5 the Safety Board recommended that the Research and Special 

Programs Administration (RSPA): 

P-98-38

Revise 49 Code of Federal Regulations Part 195 to require that pipeline 

operators periodically evaluate the effectiveness of their public education 

programs using scientific techniques. 

In December 2003, the American Petroleum Institute published its Recommended 

Practice (RP) 1162 Public Awareness Programs for Pipeline Operators. This standard 

calls for pipeline operators to periodically evaluate the effectiveness of their public 

education programs. RSPA has advised the Safety Board that organizations representing 

essentially the entire gas and hazardous liquid pipeline industry have urged RSPA to 

incorporate RP 1162 into the pipeline safety regulations and that RSPA is committed to 

incorporating by reference RP 1162 into the pipeline safety regulation (49 CFR Parts 192 

and 195). As a result, the Safety Board, on November 21, 2003, classified Safety 

Recommendation P-98-38 “ClosedAcceptable Action.” 

 

4

 Safety Recommendation P-00-1. 

5

 National Transportation Safety Board, Pipeline Rupture, Liquid Butane Release and Fire, Lively, 

Texas, August 24, 1996. Pipeline Accident Report NTSB/PAR-98/02 (Washington, D.C.: NTSB, 1998). 
 NTSB/PAB-04/01 7 

Probable 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. 

Adopted: April 6, 2004