NATIONAL

TRANSPORTATION

SAFETY BOARD

Washington, D.C. 20594

PIPELINE ACCIDENT REPORT

Natural Gas Pipeline Rupture

and Subsequent Explosion

St. Cloud, Minnesota

December 11, 1998

7178A

PB2000-916501

NTSB/PAR-00/01

Pipeline Accident Report

Natural Gas Pipeline Rupture 

and Subsequent Explosion 

St. Cloud, Minnesota

December 11, 1998

NTSB/PAR-00/01

PB2000-916501 National Transportation Safety Board

Notation 7178A 490 L’Enfant Plaza, S.W.

Adopted July 11, 2000 Washington, D.C. 20594

E P L U R IB U S U N U M

N AT I O N A L T R A S PO R TA T IO N

B O A R D

SA F E T Y

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

St. Cloud, Minnesota, December 11, 1998. Pipeline Accident Report NTSB/PAR-00/01. Washington,

DC: NTSB, 2000.

Abstract: About 10:50 a.m. on December 11, 1998, while attempting to install a utility pole support anchor

in a city sidewalk in St. Cloud, Minnesota, a communications network installation crew struck and ruptured

an underground, 1-inch-diameter, high-pressure plastic gas service pipeline, thereby precipitating a natural

gas leak. About 39 minutes later, while utility workers and emergency response personnel were taking

preliminary precautions and assessing the situation, an explosion occurred. As a result of the explosion,

4 persons were fatally injured; 1 person was seriously injured; and 10 persons, including 2 firefighters and

1 police officer, received minor injuries. Six buildings were destroyed. Damage assessments estimated

property losses at $399,000.

The major safety issues identified in this investigation are the adequacy of the safety and emergency

procedures used by Cable Constructors, Inc., crews when working in the vicinity of underground facilities

and the adequacy of St. Cloud Fire Department procedures and training for responding to natural gas leaks.

As a result of its investigation of this accident, the Safety Board makes safety recommendations to the

Research and Special Programs Administration, the Occupational Safety and Health Administration, the

Associated General Contractors of America, the National Utility Contractors Association, the Power and

Communications Contractors Association, the National Cable Television Association, the American

Public Works Association, and the International Association of Fire Chiefs.

The National Transportation Safety Board is an independent Federal agency dedicated to promoting aviation,

railroad, highway, marine, pipeline, and hazardous materials safety. Established in 1967, the agency is mandated by

Congress through the Independent Safety Board Act of 1974 to investigate transportation accidents, determine the

probable causes of the accidents, issue safety recommendations, study transportation safety issues, and evaluate the

safety effectiveness of government agencies involved in transportation. The Safety Board makes public its actions

and decisions through accident reports, safety studies, special investigation reports, safety recommendations, and

statistical reviews.

Recent publications are available in their entirety on the Web at <http://www.ntsb.gov>. Other information about

available publications also may be obtained from the Web site or by contacting:

National Transportation Safety Board

Public Inquiries Section, RE-51

490 L'Enfant Plaza, S.W.

Washington, D.C. 20594

(800) 877-6799 or (202) 314-6551

Safety Board publications may be purchased, by individual copy or by subscription, from the National Technical

Information Service. To purchase this publication, order report number PB2000-916501 from:

National Technical Information Service

5285 Port Royal Road

Springfield, Virginia 22161

(800) 553-6847 or (703) 605-6000
iii Pipeline Accident Report

Contents

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Factual Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

The Accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Personnel and Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

CCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Sirti . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

NSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Pipeline Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Background of Accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Meteorological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Medical and Pathological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Survival Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Emergency Response After the Explosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Disaster Preparedness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Fire Department Procedures and Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

NSP Public Awareness Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Site Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Gas Monitor Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Previous Underground Facility Strikes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Other Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Events Following the Accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Exclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

The Accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Contractor Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Fire Department Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Excavation Damage Prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Excess Flow Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Probable Cause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

New Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Previously Issued Recommendations 

Classified in this Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
iv Pipeline Accident Report

Executive Summary

About 10:50 a.m. on December 11, 1998, while attempting to install a utility pole

support anchor in a city sidewalk in St. Cloud, Minnesota, a communications network

installation crew struck and ruptured an underground, 1-inch-diameter, high-pressure

plastic gas service pipeline, thereby precipitating a natural gas leak. About 39 minutes

later, while utility workers and emergency response personnel were taking preliminary

precautions and assessing the situation, an explosion occurred. As a result of the

explosion, 4 persons were fatally injured; 1 person was seriously injured; and 10 persons,

including 2 firefighters and 1 police officer, received minor injuries. Six buildings were

destroyed. Damage assessments estimated property losses at $399,000.

The National Transportation Safety Board determines that the probable cause of

this accident was the lack of adequate procedures by Cable Constructors, Inc., to prevent

damage to nearby utilities when its anchor installation crews encountered unusual

conditions such as striking an underground obstacle. Contributing to the severity of the

accident was the delay by Cable Constructors, Inc., in notifying the proper authorities. 

The major safety issues identified in this investigation are the adequacy of the

safety and emergency procedures used by Cable Constructors, Inc., crews when working

in the vicinity of underground facilities and the adequacy of St. Cloud Fire Department

procedures and training for responding to natural gas leaks.

As a result of its investigation of this accident, the Safety Board made safety

recommendations to the Research and Special Programs Administration, the Occupational

Safety and Health Administration, the Associated General Contractors of America, the

National Utility Contractors Association, the Power and Communications Contractors

Association, the National Cable Television Association, the American Public Works

Association, and the International Association of Fire Chiefs. 
1 Pipeline Accident Report

Factual Information

The Accident

On December 11, 1998, a crew of four Cable Constructors, Inc., (CCI) workers

was tasked with installing a utility pole support anchor1 vertically through a concrete

sidewalk in the city of St. Cloud, Minnesota. (See figure 1.) The anchor (figure 2) was

being installed as part of a project by Seren Innovations, Inc., (Seren) to construct a fiberoptic communication system in the St. Cloud area. Sirti Ltd. (Sirti) had been hired to

provide all engineering, design, drafting, mapping, licensing, permitting and specification

development, and program management for the construction of the system, and CCI had

been hired to perform the actual construction work.

1 The anchor was a steel rod, 5 feet 6 inches long and 3/4 inch in diameter, with a closed-loop eye at the

top and a spoon-like helix, cut at an angle, at the bottom. The helix acts as a bit during installation.

Figure 1. Accident Area
Factual Information 2 Pipeline Accident Report

Before installation was begun, the crew foreman measured the distance from the

planned anchor site to the marked location of a gas pipeline owned by Northern States

Power Company (NSP) and used to provide gas service to Book Em’s Bar. Because the

distance from the marked location of the pipeline to the drill site was more than 2 feet, he

determined that the installation of the anchor could proceed.2

The workers used a jackhammer to break about a 9-inch-diameter hole in the

concrete sidewalk. They then placed an auger known as an “anchor cranker” (a gasolinepowered earth auger that had been specially modified to install anchors) on top of the

anchor, and the crew began using the machine to auger the anchor into the ground. (See

figure 3.) According to the workers, when the anchor had bored to a depth of 1 1/2 to 2

feet, it hit something hard. The object impeding the anchor’s travel was later determined

to be a large granite slab about 18 inches wide, 90 inches long, and 8 inches thick. 

The crew removed the auger and struck the top of the anchor with a sledgehammer

in an attempt to break up what crewmembers thought was a rock or rocks in the anchor’s

path. The crew then reattached the auger to the anchor, and all four men recommenced the

attempt to screw the anchor into the ground. They stated that the anchor then appeared to

proceed normally, with no further unusual resistance, and they believed the anchor had

broken through the obstacle or been deflected to the side of it. They said that “everything

went fine, just as normal” until the top of the anchor was about 12 to 18 inches from the

surface. At that point, they noticed dirt blowing out of the anchor hole and immediately

Figure 2. Unused anchor (top) and accident anchor after removal from accident site

2 The distance from the marked location and the anchor site was later determined to be 38 inches. Had

the distance been less than 2 feet, CCI policy and Minnesota State law would have required that the crew

expose the utility line before beginning installation of the anchor. 
Factual Information 3 Pipeline Accident Report

began to smell gas. They then stopped the auger and released it. At that point, according to

the foreman, “it [the auger] just laid over towards the [utility] pole.” (See figure 4.)

After telling other crewmembers to keep people off the street and away from the

leaking gas, the crew foreman went into Book Em’s Bar with a crewmember to telephone

his supervisor. The foreman reached the CCI site project manager about 10:51 a.m.3 and

told him that his crew had struck a gas pipeline while installing an anchor. The foreman

later estimated that “no more than a minute” elapsed from the time he smelled gas to the

time he made the phone call to his supervisor. 

The CCI site project manager told the foreman to follow the company’s utility

strike procedures, and he went over the procedures with the foreman. The procedures were

described in an August 19, 1998, memorandum from Sirti to all CCI supervisors. These

procedures were not written into a CCI workplace accident and injury reduction program

as required by Minnesota State law. In regard to notification, the procedures stated:

Any utility strike will require immediate notification of the utility. If gas,

immediately extinguish all ignition sources in the immediate vicinity such as

motors, smoking, divert all traffic in the area, notify the utility. Isolate the area by

barricading to restrict access. It may also be necessary to evacuate the area....

The procedure did not advise supervisors to call 911. The foreman said that after

completing the call, he told the four people in the bar of the gas leak outside and informed

them that they should not smoke, nor should they exit the building using the doorway near

the escaping gas.

Figure 3. The “anchor cranker” auger used to install the anchor that ruptured the pipeline

3 Unless otherwise noted, times used in this report are based on telephone records or witness statements.
Factual Information 4 Pipeline Accident Report

The CCI site project manager, as required by Seren’s utility damage reporting

procedures, then telephoned the Sirti safety coordinator and told him that a gas line had

been hit. According to phone records, this call was made about 10:52 a.m. The CCI site

project manager said he did not know all of the people to call in St. Cloud. The CCI site

project manager said the Sirti safety coordinator told him to call NSP and to let NSP

employees make the emergency response calls.

The Sirti safety coordinator told the CCI site project manager that he (the safety

coordinator) would immediately leave for the accident site, which he did. On the way, he

placed a cell phone call to Seren management, informing them that a gas line had been hit

and he was on his way. Some time thereafter, the CCI site project manager departed his

office for the accident site. Along the way, he placed a cell phone call to NSP’s customer

service 800 number to report the leak. According to cell phone records, this call was

placed at 11:21 a.m.

Meanwhile, the CCI foreman had gone back to the site to make sure his

crewmembers had blocked off the area. He directed that cones and orange tape be used to

help keep out vehicular traffic. Minnesota State Law, Chapter 216D.06, required an

excavator who damages an underground facility to notify the operator and “take

immediate action to protect the public and property and to minimize the hazard until the

operator’s personnel or emergency responders have arrived.” While gas was exiting the

Figure 4. Anchor installation site as revealed by postaccident excavation
Factual Information 5 Pipeline Accident Report

ground, a CCI crewmember moved the crew’s aerial truck4 into Courthouse Square and to

the north of First Street North. He parked the truck so as to help prevent southbound

Courthouse Square traffic from entering First Street North. 

After the CCI crew had placed cones and strung orange tape across First Street

North where it adjoined Ninth Avenue North, the crew waited for the emergency

responders (who, in fact, had not yet been called) and tried to keep people away from the

taped off, secured area. The CCI foreman later said,

For about the first 10 minutes, we had people coming and going, and then people

were slowly dissipating. There weren’t people coming and going anymore. So

basically the street was shut off.

By this time, a receptionist in the Stearns County Administration Building was

receiving complaints by telephone and from walk-ins of a strong smell of gas outside. The

receptionist relayed the reports downstairs to the office of the Stearns County building

facilities director. Upon learning of the reports, the facilities director left by the west

entrance of the administration building to investigate. Once outside, he called to have an

air handler turned off in the Administration Building.

Knowing of construction on Second Street North, the facilities director approached

the site and asked the excavators if they had hit a gas line. The excavators said they had

not and pointed him toward the CCI workers. After walking past the police department

building and smelling gas, he asked the CCI workers if they had damaged a gas line. The

crew foreman told him they had. The director asked if the crew had called the fire

department, and the crew foreman reported that they had not. The director then, about

11:05 a.m., placed a cell phone call to the Stearns County chief deputy sheriff and reported

the leak. The deputy sheriff then called the sheriff’s department dispatcher, who

immediately called the St. Cloud Fire Department. At 11:06 a.m., Engine Company 21,

based at Fire Station 1, about 2 blocks from the leak site, was dispatched to the scene.

According to telephone records, at 11:07 a.m., the fire department dispatcher notified the

NSP dispatcher of the leak.

Also about 11:06 a.m., St. Cloud police units 41 and 42 were assigned for traffic

control in front of Book Em’s Bar because of the gas leak. About the same time, unit 40, a

police sergeant, reported that the area had already been barricaded and that police

assistance was available to the fire department through the dispatcher. 

The firefighters arrived on the scene about 11:08 a.m. According to interviews, a

CCI employee moved the tape to allow the engine company into the secured area. The first

responders in the engine company included a lieutenant and three firefighters. The

lieutenant said he immediately took notice of the wind direction when he arrived at the

site. He later said that he planned to use the information to decide which buildings needed

to be evacuated first if evacuation became necessary.

4 This truck is known as an aerial truck because it had a lift to allow workers to connect cables to utility

poles. 
Factual Information 6 Pipeline Accident Report

One of the firefighters, accompanied by another firefighter, began testing the area

using a hazardous and combustible gas monitor.5 After radio approval from his lieutenant,

and within a minute of arrival, the other firefighter moved the fire truck to the east end of

First Street North to eliminate a possible ignition source. 

The Sirti safety coordinator said he arrived at the scene about 11:15 a.m. He said

he parked across the street from the police station and walked to the accident site. He took

several photographs of the anchor location and the general area around the scene. 

Four vehicles were parked on First Street North next to Book Em’s Bar. The St.

Cloud Fire Department lieutenant told the firefighters that NSP would need to bring heavy

equipment into the area to repair the leak and that the vehicles would have to be moved.

The lieutenant then walked to the police department building and asked that the license

numbers for the parked vehicles be researched and their owners contacted. None of the

owners were contacted, but they all eventually came out of nearby buildings and moved

their vehicles.

With another firefighter at his side, the firefighter with the gas monitorfirst tested

the concentration of natural gas above the leak site. He then performed the same test

alongside the buildings housing Book Em’s Bar and Bellantti’s Pizza and Deli. The

firefighter who carried the gas monitor said the area “smelled really bad.” He said he

essentially got no reading when he placed the monitor directly adjacent to the hole in the

ground made by the anchor. He said that the monitor’s lower explosive limit (LEL)

reading went from -2 to 0.6 A firefighter stated that they had not had time to do a fresh-air

calibration7 of the monitor because of the short distance between Fire Station 1 and the

accident site. 

After the fire truck moved to the east end of First Street North, the CCI site project

manager arrived on Courthouse Square. He parked his truck on Courthouse Square so as

to prevent traffic from entering the east end of First Street North. With the CCI project

manager’s truck on one side of Courthouse Square and the crewmember’s aerial truck on

the other side, traffic could not travel from Courthouse Square toward the east end of First

Street North. 

About 11:16 a.m., two NSP trucks arrived. As was done earlier for the fire

department, a CCI lineman moved the tape to permit entry for both NSP trucks. An NSP

gas technician specialist arrived in one truck, which he parked on the street alongside the

damage area. He then went to the location of the damage to assess its extent and to talk to

the CCI foreman. An NSP locator technician (the individual who finds and marks the

5 The hazardous and combustible gas monitor used by the St. Cloud Fire Department was similar to a

combustible gas indicator except that it had sensors for both combustible and toxic gases. 

6 Lower explosive limit refers to the lowest concentration of a flammable gas that can be ignited. NSP

standards state that the LEL of its natural gas is about 4.8 percent. Gas monitors typically indicate the

percentage of LEL, meaning that an NSP gas monitor reading of 100 percent would indicate a natural gas

concentration of about 4.8 percent. 

7 To ensure accurate readings, the monitor is to be turned on in fresh air, after which it automatically

completes a 20-second self-test and start-up sequence.
Factual Information 7 Pipeline Accident Report

locations of buried utilities) was in the other truck, which was parked behind the gas

technician specialist’s truck. With NSP personnel on scene, two of the fire department

responders joined the third already at the fire truck, while the lieutenant remained in the

vicinity of the leak. 

At the anchor leak site, the NSP gas technician specialist asked the CCI foreman to

fill out a damage report detailing how the gas line was damaged and providing the address

of the responsible contractor. While this report was being filled out, the NSP gas

technician specialist was readying his equipment. 

Witnesses stated that after the form was completed, the NSP gas technician

specialist entered Book Em’s Bar at street level (the building did not have a basement).

Inside the bar, he took readings on a combustible gas indicator and was overheard stating

he obtained a reading of 7 percent.8 Bar patrons said the gas technician specialist then left

the bar to look for an entrance to the basement of the adjacent building, which housed

Bellanti’s Pizza and Deli. The four persons who were in the bar during this time later told

police that no one at any time asked them to evacuate the building. 

While the gas technician specialist was taking his readings, according to witness

statements, the NSP locator technician was determining if the service line had been

properly marked. He was also seen assisting with the movement of a vehicle from the

secured area. According to radio and cell phone records, about 11:29 a.m., an explosion

occurred in the basement of the building where Bellanti’s Pizza was located.

Three firefighters were in their truck at the time of the explosion. They reported

that they saw no fire but that they could see little because their vehicle was immediately

enveloped in a cloud of dust. Two of the firefighters exited the fire truck while the third

used the radio to report the explosion and request ambulance service. He said he “knew

that there were injuries.” A police officer patrolling nearby also radioed a report of the

explosion. After making the report, one of the firefighters then moved the truck to the

northeast, putting the county facilities building between the fire truck and the explosion

site.

According to NSP, when the NSP gas technician specialist received the call of the

leak, about 11:09 a.m., he immediately called for a company construction crew, which

was equipped to shut down the damaged portion of the line. At the time of the explosion,

this three-person crew was 2 blocks away from the accident site. About 11:30 a.m., the

NSP construction crew foreman radioed the NSP dispatcher to report the explosion. The

NSP dispatcher directed 26 gas technicians to the explosion site. An NSP manager stated

that the technicians were sent to help close off the damaged line and to enter and check all

adjacent buildings in the surrounding area for potential gas-related problems. NSP

workers stopped the flow of gas to the damaged gas line at 12:25 p.m. and shut off

electrical power at 12:31 p.m. 

8 Although the gas technician specialist was killed in the explosion and the gas monitor was not

recovered, because NSP employees were trained to use their monitors to measure LEL, the 7 percent

probably referred to the LEL rather than to the concentration of gas in the air.
Factual Information 8 Pipeline Accident Report

According to the report of the Minnesota State fire marshal, the explosion occurred

in the basement of the building where Bellanti’s Pizza was located. The basement walls

were made of stacked stones and crumbling mortar. According to the fire marshal’s report,

gas collected in the basement of the building and was ignited by an unknown source. In

the basement of the building were several potential sources of ignition, including gas

water heaters.

Injuries

Damage

In addition to the building containing Bellantti’s Pizza and Deli, the explosion

destroyed the buildings containing Book Em’s Bar, Tom’s Bar, and Bartsh Bail Bonds,

and the two buildings containing the Hall Law Offices. The law office buildings were

joined with a fire door. The blast also damaged the Stearns County court facilities building

and the buildings housing Taco John’s and Howies Bar. According to the St. Cloud city

assessor, the damage assessment for the buildings destroyed by the natural gas explosion

was $399,000. (See figure 5.)

Personnel and Training

CCI

The CCI crew foreman had a total of 14 nonconsecutive years’ experience with the

company, about half of it as a foreman. He had taken 3 years off the job for personal

business and had returned to CCI as a lineman about 3 months before the accident. He said

he had received no formal refresher training upon his return. He had been promoted back

to foreman about 2 weeks before the accident. 

Table 1. Injuries

Type of Injurya

a 49 Code of Federal Regulations 830.2 defines fatal injury as “any injury which results in death within 30 days of an 

accident” and serious injury as “an injury which: (1) requires hospitalization for more than 48 hours, commencing within 

7 days from the date the injury was received; (2) results in a fracture of any bone (except simple fractures of fingers, toes, 

or nose); (3) causes severe hemorrhages, nerve, or tendon damage; (4) involves any internal organ; or (5) involves second 

or third-degree burns, or any affecting more than 5 percent of the body surface.”

NSP 

Employees

Emergency 

Responders

Building 

Occupants Other Total

Fatal 2011 4

Serious 0010 1

Minor 0325 10

Total 2 3 4 6 15
Factual Information 9 Pipeline Accident Report

One lineman on the crew had been with CCI for 5 1/2 months. Another CCI

lineman had about 3 months’ experience before the accident. This lineman was a

machinist before coming to CCI, and he had no previous communications or cable

installation experience. The third lineman on the crew said that he had been working for

CCI for only about 2 weeks but that he had 19 months’ experience as a lineman before

joining CCI.

The CCI site project manager had been working for CCI for 3 years. Before this,

he had worked for a cable installation company and as a self-employed cable installer. 

CCI conducted initial training for new employees. Much of the initial training was

task-related and was focused toward reviewing the work that they would be performing.

The initial training also entailed working in the field with experienced individuals who

would show new employees the proper way to complete tasks such as pole-climbing and

running and overlashing cable. 

The initial training covered equipment related to worker safety (hard hats, vests,

and cones), but it did not cover what an employee should do in the event of a natural gas

pipeline strike. According to meeting records, pipeline strikes were addressed at a special

October 23, 1998, meeting held among Seren, NSP, Heath Consultants (utility locating),9

and CCI. Participants at the meeting included Seren’s director of network construction and

Figure 5. Postaccident aerial view of affected area

9 Utility companies sometimes use utility-locating services rather than their own employees. 
Factual Information 10 Pipeline Accident Report

operations, CCI’s site project manager, and NSP’s district operations manager and

damage prevention coordinator. Although Sirti was the safety project coordinator, no one

from Sirti is listed as attending this meeting. The meeting covered related subjects such as

locating underground facilities.

According to the meeting minutes, the meeting was held because “NSP and Seren

together decided that we needed a meeting to better control the situation we have with

safety as it related to locating gas and electric services, particularly given recent incidents

that have occurred.” According to officials, a number of incidents had occurred in which

yellow-paint locate marks had not been placed directly above the underground facility.

Before the meeting, NSP had been contracting out its utility locating to Heath Consultants.

As a result of the meeting, NSP assigned two full-time utility locators to the Seren project

and put the contract locator under the direct supervision of an NSP locator. To help ensure

that locate marks were located directly above underground facilities, the idea of preconstruction “walkouts” was discussed, along with the need for daily meetings at

excavation sites between the locator and Seren excavators to pinpoint utility locations. It

was determined that improved mapping and map reading would also help ensure that

locate marks would be placed directly above underground facilities. During the meeting,

the CCI site project manager specified the need for a 24-inch distance between the

excavation and the locate marks.

Emergency procedures for Seren contractors were also discussed at the October 23

meeting. The topic discussion started when Seren’s director of network construction and

operations asked “Once we do have a strike, what is the procedure?” NSP officials then

said they would send out a person immediately and that police and fire departments would

be needed to keep the crowds away. Later in the meeting, NSP provided attendees with a

“tip sheet” containing a step-by-step process in the event an underground natural gas line

should be struck during excavation or other construction. The tip sheet advised workers

first to shut down all equipment in the immediate area, then “Call 911 and/or radio

dispatcher and request that they call 911 to alert the Fire and Police Departments.” No tip

sheet or written emergency procedures were available at the site of the accident. 

CCI construction crews were required to attend “construction” meetings every

Wednesday at 10 a.m. According to CCI, at these meetings, workers would discuss

incidents that occurred during the previous week. These Sirti-run meetings were also

called “safety meetings” because Sirti maintained a log of utility strikes, and the workers

would analyze how an incident occurred and how a similar incident could be prevented in

the future. 

Sirti

The Sirti safety coordinator who responded to the accident had completed a

Minnesota Safety Council course entitled “An Introduction to Occupational Safety” in

June 1998. 
Factual Information 11 Pipeline Accident Report

NSP

The NSP gas technician specialist initially sent to check the leak was killed in the

explosion. Company records show that the technician had completed the company’s “Gas

Emergency Training” course in February 1998 and had completed the final course test

with no errors. 

The locator technician who responded to the leak was also killed. He had taken the

gas emergency training course in February 1995 and had passed the final test. He had also

taken a course entitled “Recognizing Emergency Conditions” in August 1995. He was not

required to take the training course annually because he was not a gas operations

employee and therefore would not respond to a gas leak in the same capacity as a gas

technician. Because NSP is also the provider of electric power for St. Cloud, the locator

technician would locate both electric and gas underground facilities. He had been the

individual who had marked the location of the pipeline before the anchor installation was

begun, and he went to the site to verify that he had properly marked the pipeline’s

location. 

According to NSP officials, the company offered a number of courses designed to

prepare NSP employees to respond to gas emergencies. The officials stated that the

training has a special section on outside leak emergencies and that a considerable part of

this section is about leak classification guidelines. Leak classifications involve the

volume, location, area, system pressure, concentration, duration, and spread rate of a leak.

Company representatives said employees were taught that a leak classification involves

the possible migration of the gas and the proximity of a leak to a building foundation. The

gas emergency training course lesson plans state that experience is imperative in

evaluating a leak and assigning repair priority and that experience is needed to recognize

where gas may be migrating. 

In addition to the above training, NSP’s St. Cloud office gas operations employees

were required to attend a half-day fire school during the summer and 90-minute safety

meetings each month. These meetings covered 17 planned subjects such as carbon

monoxide safety, heat stress, and winter safety. An NSP training officer stated that the

safety meetings were less structured or planned than the company’s training courses. None

of the safety meetings specifically covered the procedures needed in the event of an

underground gas leak next to a building. 

The NSP Gas Safety Training Department required that new gas operations

employees go through a formal apprenticeship program. On an ongoing basis, all gas

operations employees are required to take a first-aid course every 3 years and 11 different

courses annually. Required courses included confined space work, excavation and

shoring, and gas emergency training.
Factual Information 12 Pipeline Accident Report

Pipeline Operations

NSP completed the original installation of the gas service line serving Book Em’s

Bar on October 29, 1982. The polyethylene main and service pipelines were installed for

use at 7 inches water column pressure (approximately 1/4 psig). According to the

company, NSP planned to possibly upgrade the system later to high pressure, and the

pipelines were tested to 100 psig after installation. An excess flow valve (EFV) was not

required by regulation and was not installed. 

Records show that the service pipeline and meter set to Book Em’s Bar were

“uprated” to high pressure on August 19, 1998. No excavation was done to uprate the

pipeline. The service pipeline meter set was changed to fit a high-pressure, 60 psig system,

and the service pipeline was again tested to 100 psig. After August 19, 1998, and at the

time of the accident, the pipeline operating pressure at the outlet of the regulator station

was about 60 psig.

Background of Accident

On March 10, 1998, a contract was completed between Seren, a fully owned

subsidiary of NSP, and Sirti. The contract stipulated that Sirti would provide all

engineering, design, drafting, mapping, licensing, permitting, and specification

development for the construction of a two-way fiber-optic telecommunications system

throughout the St. Cloud area. 

On July 15, 1998, Seren authorized Sirti to provide the construction project

management services for the St. Cloud telecommunications system. As project manager,

Sirti would coordinate all construction and testing activities and administer all

contractor’s documents. Contract correspondence between Seren and Sirti indicated that

Sirti would hire a safety manager who would prepare a safety manual and be responsible

for enforcing all Federal and State regulations.

On August 5, 1998, Seren signed a contract with CCI to construct the

telecommunications system throughout the St. Cloud area. Although Sirti was already

chosen to be the project and safety manager, the contract between Seren and CCI had no

mention of Sirti. CCI officials were aware that Sirti was the project manager, and CCI

subleased office and warehouse space from Sirti. CCI started field construction under this

contract on August 10, 1998. 

On December 8, 1998, after using the Gopher State One-Call system, CCI’s aerial

construction manager met with eight underground facility operators,10 including NSP, and

informed them of the locations where CCI planned to install utility-pole support anchors.

10 The underground facility operators included the city of St. Cloud, the city of Waite Park, TCI

Cablevision, the State of Minnesota Department of Transportation, Norstan Communications, NSP, Seren,

and U.S. West (telephone).
Factual Information 13 Pipeline Accident Report

The facility operators marked their facilities in these areas. CCI planned to do the work at

these sites between December 8 and December 11. The One-Call ticket was for 21

locations. 

Meteorological Information

According to weather data recorded at the St. Cloud airport, at the time of the

accident, the skies were clear and the wind was blowing out of the southwest at 8 mph.

Climatological data for the city of St. Cloud indicate that the weather for a month before

the accident was unseasonably mild, with the average temperature being 10.7° F warmer

than normally recorded for that time of year. Had it not been for the unseasonably warm

weather, CCI would have had to postpone the anchor installations because of frozen

ground. 

Medical and Pathological Information

Four people were fatally injured in the accident, including the NSP gas technician

and the NSP locator. Also killed were a pedestrian walking outside the taped-off area and

a tenant of one of the rented rooms above Bellantti’s Pizza. The tenant was found in the

basement of the collapsed building with debris beneath and over his body. Cause of death

in each case was multiple traumatic injuries due to natural gas explosion. 

Eleven people, including two firefighters and one police officer, were injured. An

employee of the law offices, one of four trapped persons extricated from the rear of the

law offices building, sustained serious injuries from falling debris. The remaining 10

people received minor injuries, including abrasions, lacerations, and inhalation injuries.

They were treated at St. Cloud Hospital and released. 

U.S. Department of Transportation (DOT) rules for postaccident alcohol and drug

testing (49 Code of Federal Regulations (CFR) 199.3 and 11(b)) do not cover workers

such as CCI employees at the scene of the gas explosion or those involved in the

excavation activities that preceded the accident. Covered employees are those persons

who perform operating, maintenance, or emergency response functions regulated by 49

CFR Parts 192, 193, or 195. 

After discussions with NSP and Seren, CCI, about 10 hours after the accident,

directed five involved employees to St. Cloud Hospital for the collection of specimens.

The five employees included the crew, the crew foreman, and the project manager, who

was the first member of management to be notified of the leak. Arrangements were made

for MedTox Laboratories, Inc., in St. Paul, Minnesota,11 to collect the specimens and

11 MedTox Laboratories, Inc., was on a U.S. Department of Health and Human Services list of

laboratories meeting minimum standards to perform urine drug testing.
Factual Information 14 Pipeline Accident Report

perform the tests. According to the times indicated on the MedTox laboratory sheets for

the blood and urine test reports, the earliest specimen collection was 9:35 a.m. on the day

of the accident, and the last collection was 10 a.m. the next day.12 The other collections

were recorded as taking place between 10:30 p.m. and 11:20 p.m. on December 11. The

MedTox test results for alcohol in blood were positive at or above 0.02 g/dl for one

employee. For another employee, marijuana metabolite was present in urine at or above

the 15 ng/ml level. 

The Safety Board asked the crewmembers about their activities between the time

of the accident and the time their specimens were collected. They said they returned to the

shop for their paychecks. On the way home, they went together to a bar and had “several”

drinks. The foreman said that he drank a “couple” more beers when he got home.

Everyone on the crew said that they had not consumed alcohol or used drugs within 8

hours of reporting for work on the morning of the accident.

The specimens remaining after the MedTox tests were shipped to the Civil

Aeromedical Institute (CAMI) for additional testing at the request of the Safety Board.

The CAMI tests revealed the presence of alcohol and marijuana in the specimens of two of

those tested. 

According to CCI officials, after the accident, the company began requiring

preemployment drug screening and conducting random drug testing of its employees. 

Survival Aspects

Emergency Response After the Explosion

Immediately after the explosion, one engine company each responded from St.

Cloud Fire Department’s Fire Stations 2 and 3, and a ladder truck responded from Fire

Station 1. Fire department personnel notified Gold Cross Ambulance Service to respond

and requested heavy excavation equipment. Crewmembers of Engine Company 21,

already on scene, began search and rescue operations immediately.

Four people were trapped inside the rear portion of the Hall law offices, which was

between the Bellantti’s building and Tom’s Bar. Three of those trapped were extricated by

firefighters within 20 minutes. Some 30 minutes after that, the fourth person was freed and

taken to the hospital. None of these individuals reported seeing any NSP or fire

department personnel before the explosion. 

At 11:30 a.m., St. Cloud Police Department Unit 43 advised the Stearns County

Sheriff’s Department dispatcher of the explosion. All available ambulances were asked to

12 MedTox forms for one employee show the time of urine collection as 9:35 a.m. on December 11, which

was about 2 hours before the explosion. The time shown for collection of a blood specimen for the same

employee was 10 a.m. on December 12, the day following the accident. The Safety Board asked for but did

not receive information from MedTox that would explain these discrepancies. 
Factual Information 15 Pipeline Accident Report

respond to the scene, as were all available law enforcement personnel. A request was also

made for construction equipment. 

About the same time, the St. Cloud fire chief and the assistant fire chief, who was

the incident commander, arrived on scene. At 11:31 a.m., the St. Cloud Police Department

began evacuating the immediate area, including Courthouse Square and the north side of

the courthouse building. At this time, all of the St. Cloud off-duty firefighters and

volunteer division firefighters were called to report to duty. At 11:32 a.m., a command

post was established 100 feet west of the intersection of Ninth Avenue North and First

Street North and a staging area was established at the rear of Fire Station 1. Also about

11:32 a.m., Engine 21 firefighters notified the incident commander that they were going to

begin evacuation of the Stearns County courts facilities building. At 11:33 a.m., the

incident commander requested additional NSP personnel because of the gas leak and

downed electrical wires. The first ambulance arrived at 11:34 a.m.

At 11:37 a.m., the fire chief activated the St. Cloud Emergency Action Plan. At

11:38 a.m., the fire chief asked for help from the Waite Park and Sauk Rapids fire

departments. 

At 11:42 a.m., the St. Cloud police established an evacuation perimeter. This

perimeter included the Law Enforcement Center, the courthouse, and the Stearns County

Administration Building. 

At 11:44 a.m., Gold Cross Ambulance Service called the St. Cloud Hospital and

informed the emergency trauma center charge nurse of the gas explosion and advised her

that approximately 20 patients possibly could be transported to the hospital. Subsequently,

the hospital evaluated its resources and determined that three air ambulances were

available to transport patients to burn centers if necessary. 

By 11:47 a.m., all injured survivors, with the exception of the seriously injured and

trapped victim, had been removed from the immediate area surrounding the explosion.

The evacuation perimeter was further secured using police line tape and road barricades

with security checkpoints established.

At 11:50 a.m., the owner of the building housing Bellantti’s Pizza informed a

police supervisor that two rooms on the second floor of the Bellantti’s building were

rented. At 12:07 p.m., the incident commander called for the Anoka County Search and

Rescue Canine unit. 

At 12:09 p.m., St. Cloud Hospital initiated its disaster plan and notified 50 medical

professionals to respond to an upper floor staging area. The emergency trauma center

monitored the activities of the ambulance crews on site and was kept informed on the

conditions of patients and their transportation to the hospital. A total of 11 people were

either transported by ambulance or arrived by private vehicle at the hospital. At 1:30 p.m.,

the hospital’s disaster plan was discontinued.
Factual Information 16 Pipeline Accident Report

At 1:51 p.m., the Anoka County Search and Rescue Canine Unit arrived on scene.

At 2:24 p.m., St. Cloud police received reports that two individuals had been in a rented

room above Bellantti’s at the time of the explosion. At 3 p.m., the police department

confirmed that all four people who had been inside Book Em’s Bar at the time of the

explosion had been accounted for. At 3:05 p.m., police officers were assigned to start

door-to-door checks within the affected area. At the same time, Red Cross workers were

on site at a nearby home for senior citizens to assist with a possible evacuation. 

Search and rescue operations continued with the use of manual and heavy

equipment until approximately 10 p.m., in the event that more victims were buried in the

debris; however, none were found. At 10 p.m., the St. Cloud Police Department and the

34th Military Police Company of the Minnesota National Guard secured the area for the

night. NSP continued operations in the area, restoring power and gas service to the senior

citizens home and to other buildings in the area.

Disaster Preparedness

The city of St. Cloud implemented its disaster plan for the accident. The purpose

of the basic plan was to ensure the effective, coordinated use of the resources available to

the city so as to: (1) maximize the protection of life and property; (2) ensure the continuity

of government; (3) sustain survivors; and (4) repair essential facilities and utilities. Prior

to the accident, the most recent certification of the plan by local authorities was

September 9, 1998.

The last full-scale disaster drill conducted by the city of St. Cloud before the

accident was on May 21, 1998. The drill simulated an airplane accident at St. Cloud

airport. According to hospital officials, St. Cloud Hospital routinely performs two internal

disaster drills annually.

Fire Department Procedures and Training

Although all of the fire department responders were trained on the basic

characteristics of natural gas, at the time of the accident, the St. Cloud Fire Department

had no written procedures in place providing detailed guidance on responding to natural

gas leaks. The firefighters were instructed during in-house training, State-sponsored

training, and training sponsored by NSP to be aware of wind direction as well as the

general characteristics of natural gas. The American Gas Association’s (AGA’s) pamphlet

A Guide to Controlling Natural Gas in Emergencies was also reviewed and distributed by

NSP. Prepared by the AGA as a guide to firefighters, the pamphlet provides a brief

overview of natural gas and its characteristics. In a section dealing with steps to take when

gas is escaping outside a building, the pamphlet recommends:

If unignited gas is escaping from the ground, from an excavation or from an open

pipe outside a building - NOTIFY THE GAS COMPANY IMMEDIATELY. A

safe area surrounding the location should be cleared, roped or barricaded.

Extinguish all open flames. Prohibit smoking. Check surrounding buildings,

cellars in particular, for any presence of gas odors. Restrict or reroute all traffic

until gas company personnel can bring the gas flow under control.
Factual Information 17 Pipeline Accident Report

This pamphlet outlined the actions to take in the event of an underground gas leak

next to a building.

NSP trains its employees that gas can migrate underground. As a part of its public

awareness program (see next section), NSP provides information and instructional classes

to fire departments on the hazards of natural gas. Before the accident, the most recent

training class regarding natural gas had been provided to the St. Cloud Fire Department in

October 1995. 

NSP Public Awareness Program

According to company officials, NSP has a public awareness plan for the safety of

the public and contractors working in and around natural gas. The plan covers excavation

safety, and the information is communicated through radio, television, and newspaper ads,

in addition to billing inserts. All forms of communication emphasize the need to call

Gopher State One-Call before excavating. Some forms of communication, especially

newspaper ads and billing inserts, include whom to call for carbon monoxide problems,

gas leaks, or incidents when the odor of natural gas is detected. The ads and inserts state

that in the case of a suspected gas leak, a person should evacuate a building, should not

turn on any light switches, and should call NSP from outside the building. Excavation

safety includes working with various groups such as the Gopher State One-Call, the

Metropolitan Utility Coordinating Committee, the Minnesota Utility Contractors

Association, and other groups to prevent excavation damage.

Investigation

Site Description

Postaccident Safety Board investigation revealed a yellow paint mark on the

sidewalk in direct line with two other yellow paint marks, one over and perpendicular to

the curb and another on the sidewalk closer to Book Em’s. The paint marks ran in a

straight line toward a gas riser located inches from the Book Em’s building wall. Each of

the paint marks was about 2 feet long and was directly over the gas service pipeline. 

Gas Monitor Testing

Four days after the accident, with fire department and Safety Board personnel

present, the gas monitor readings that were obtained by firefighters at the accident scene

before the accident were downloaded from the memory device within the monitor, and the

monitor was calibrated. The calibration of the monitor was tested by exposing the unit to a

calibration gas with a concentration that was 50 percent of LEL. When tested against this

gas, the monitor registered 34 percent of LEL. Also, the timing mechanism on the monitor

was in error by about 4 minutes. 
Factual Information 18 Pipeline Accident Report

Previous Underground Facility Strikes

Although the gas line location in this accident was accurately marked, during the

investigation, the Sirti safety manager stated that an NSP locating contractor had done a

poor locating job in the past. Sirti submitted to the Safety Board a list of 37 previous

underground facility strikes, with several attributed to improperly located or unmarked

underground facilities.

NSP records showed that as a result of excavator error, CCI and its subcontractor

had previously damaged NSP natural gas pipelines, including incidents on October 7 and

30, 1998. CCI had also damaged NSP’s underground electrical facilities and the

underground facilities of others. About 1 year before this accident, CCI had struck a

telephone cable and was cited and fined by the Minnesota Office of Pipeline Safety.

According to NSP, while Seren contractors had been installing

telecommunications in the St. Cloud geographic area, they had damaged underground

natural gas facilities in 15 locations (including the accident location) over a 4-month

period. In about half of the incidents listed, damage was attributed to improper locating.

Seren subcontractors other than CCI had also damaged NSP natural gas pipelines.

On December 2, 1998, a Seren contractor damaged a gas main. The St. Cloud Fire

Department responded and NSP had to bypass the leak to avoid disrupting service to about

100 customers.

Other Information

Events Following the Accident

After the accident, the Minnesota Occupational Safety and Health Administration

(MNOSHA) cited CCI for not having a written plan to avoid damage to the underground

gas lines in and near the construction area and for not having a complete workplace

accident and injury reduction (AWAIR) program. The CCI program did not list methods

to identify, analyze, and control existing hazards. MNOSHA also cited Sirti and Seren for

not having a complete AWAIR program. 

Following the accident, Seren replaced CCI as a contractor for the project. The

new contractor was removed after it too was involved in damaging underground facilities.

To prevent further incidents, the companies involved and local authorities jointly decided

that all future Seren contractors would be required to undergo training with NSP.

Additionally, NSP would have a safety inspector at each site when anchors were being

installed.

As part of its postaccident activities, the St. Cloud Fire Department developed, in

conjunction with NSP, standard operating guidelines for responding to natural gas

emergencies. The guidelines state that gas can migrate underground into buildings, that

gas monitors should be used both outside and inside buildings to check for the
Factual Information 19 Pipeline Accident Report

concentration of gas, that ignition sources should be eliminated and buildings ventilated,

and that people in the vicinity should be evacuated to a safe area. The department has also

revised its standard operating procedures to direct that firefighters (1) not rely exclusively

on gas monitors to detect gas concentrations, (2) eliminate possible sources of ignition

until the leak is stopped, (3) evacuate people and maintain site security, and (4) detect

possible underground migration by checking buildings, manholes, and confined spaces in

the affected area. The procedures note that “it can take several hours for the Gas Company

to shut off gas in a large high-pressure pipeline.”

In a June 5, 2000, letter to the Safety Board, the St. Cloud Fire Department

outlined steps it had taken to ensure the proper calibration of its gas monitors and noted

that NSP had provided the department with three gas monitors that NSP calibrates and

maintains. 

Since the accident, the city of St. Cloud has adopted a right-of-way management

ordinance and hired a specialist to manage the ordinance. The ordinance requires people

working in an area designated as having critical facilities (high-risk areas) to submit a gas

safety plan with all their permit applications. The ordinance imposes certain requirements

for work in these areas depending on the nature of the work and the risks involved. The

city, in conjunction with industry representatives, has mapped all the critical facility areas.

After the accident, CCI established a new safety and health program patterned

after the Minnesota State AWAIR program. The company hired a full-time safety

manager. CCI had all company project managers attend a 10-hour construction awareness

class. CCI also reported to the Safety Board that it has enhanced its employee training.

CCI now has procedures in place that require 911 to be called immediately in the event a

gas line is ruptured. 

Effective August 1, 1999, the State of Minnesota revised Minnesota Statute 216D

to require any excavator who breaches a pipeline containing hazardous gas or liquid to

immediately notify 911. The law states, in part:

If any damage occurs to an underground facility or its protective covering, the

excavator shall notify the operator promptly. When the operator receives a

damage notice, the operator shall promptly dispatch personnel to the damage area

to investigate. If the damage results in the escape of any flammable, toxic, or

corrosive gas or liquid or endangers life, health, or property, the excavator

responsible shall immediately notify the operator and the 911 public safety

answering point...and take immediate action to protect the public and property.

The director of the Minnesota Division of Emergency Management told Safety

Board investigators that State 911 emergency call centers had recorded no noticeable

increase in calls to 911 since enactment of the law and that, in the opinion of the official,

the law has ensured more timely notification of authorities after excavation damage. 
20 Pipeline Accident Report

Analysis

The explosion in the St. Cloud accident occurred in the building housing Bellanti’s

Pizza and Deli. The escaping natural gas from the damaged pipeline apparently migrated

underground, through the crumbling foundation of the building, and into the basement.

There, exposed to several potential sources of ignition, it exploded. 

Because of the delay in notifying the gas company and emergency response

personnel, about 18 minutes elapsed from the time the pipeline was ruptured until the first

firefighters arrived (about 21 minutes before the explosion). About 26 minutes after the

rupture (about 13 minutes before the explosion), gas company personnel arrived. An NSP

gas technician specialist was assessing the hazard when the explosion occurred.

The major safety issues identified in this investigation are the adequacy of the

safety and emergency procedures used by CCI crews when working in the vicinity of

underground facilities and the adequacy of St. Cloud Fire Department procedures and

training for responding to natural gas leaks.

The remainder of this analysis addresses factors that were eliminated as causal or

contributory to this accident, followed by a discussion of the major safety issues.

Exclusions

NSP marked the location of a nearby gas service line before the CCI construction

crew began installing the utility pole anchor through the sidewalk next to the building

housing Book-Em’s Bar and Bellanti’s Pizza. Postaccident excavations confirmed the

accuracy of the paint marks that indicated the location of the natural gas line. The Safety

Board concludes that the marked location of the ruptured gas line was accurate and was

therefore not a factor in this accident.

The CCI crew knew immediately that they had struck and ruptured a gas line when

they saw dirt blowing back around the anchor and smelled gas, and they took actions

consistent with procedures established by the company. The foreman promptly notified

CCI management of the leak, and the crew began restricting public vehicle access to the

area. 

Toxicological testing of blood and urine specimens revealed that alcohol or

marijuana, or both, was present in some of the involved employees; however, the

specimens were collected after the employees had returned to their homes for the evening,

and the testing could not determine how much alcohol was ingested or when the alcohol

and marijuana had been used. 
Analysis 21 Pipeline Accident Report

No one reported observing any actions that could be construed as indicating

impairment on the part of individuals in the crew who tested positive for alcohol or

marijuana while those employees were working on the morning of the accident.

Moreover, the crew’s collective actions after the leak showed prompt and full compliance

with CCI procedures, as well as with the instructions given to the foreman on the

telephone by the project manager. The Safety Board therefore concludes that while

toxicological testing performed after this accident was not useful for determining whether

alcohol or drugs had any influence on the performance of the CCI crewmembers while

they were installing the anchor, the crewmembers’ actions before and after the rupture

indicate that they were likely not impaired by alcohol or drugs at the time of the accident.

The Accident

Installation of the anchor was begun some 38 inches from the marked location of

the underground gas line. This distance was 14 inches beyond the 2-foot margin provided

for in CCI procedures and Minnesota State law to allow for a possible error in the marking

of the location of the gas line. But while this 38-inch distance appeared to be adequate to

ensure a safe installation, the length of the anchor was about 66 inches. At this length, the

anchor could easily span the distance from the entry point to the pipeline if it were

installed at an angle rather than vertically. 

The CCI crew stated that they intended to install the anchor vertically, and no

evidence was found to indicate that the anchor did not enter the ground vertically. But

when the anchor struck the buried granite slab, the crewmembers followed their

customary practice and struck the top of the anchor with a hammer until they perceived

that the anchor had broken through the obstacle or had deflected off to its side. As the

investigation later determined, the anchor had not broken through but had bent and

deflected. The anchor apparently continued to bend as the four men applied pressure to the

anchor cranker in their attempt to complete the installation. The investigation determined

and postaccident excavation revealed that the anchor bent and followed along the upper

surface of the buried granite slab until the cutting helix on the anchor tip dropped off the

end of the slab, thus striking and rupturing the pipeline. 

CCI procedures for protecting underground utilities did not address the risks

associated with abnormal conditions underground that could render normal precautions

inadequate. The Safety Board found no evidence that anchor installation crews were made

aware that even if installation is begun at a safe distance from a buried utility, safety can

be compromised if the anchor is allowed to assume an angled path underground. Such a

deflection could endanger an underground utility and present a risk to the public. The

Safety Board concludes that CCI’s anchor installation procedures were inadequate in that

they did not address steps to take under unusual circumstances (such as striking a

significant underground obstacle) to ensure that buried utilities were protected during the

entire installation process, including the underground portion.
Analysis 22 Pipeline Accident Report

In its investigation of a July 21, 1997, accident in Indianapolis, Indiana,13 the

Safety Board found that adequate controls were not in place to prevent an underground

pipeline from being damaged during directional drilling, even though indications above

ground were that an adequate safety margin was being observed. In the view of the Safety

Board, excavation procedures are inadequate if they do not account for the possibility that

unusual conditions could negate otherwise effective attempts to protect buried utilities.

The Safety Board therefore believes that the Associated General Contractors of America,

the National Utility Contractors Association, the Power and Communications Contractors

Association, the National Cable Television Association, and the American Public Works

Association should advise their memberships to review and revise their anchor installation

procedures as necessary to ensure that safety margins around buried utilities are absolutely

observed not only above ground but throughout the installation process.

Contractor Response

Within 1 minute of striking the gas line, the CCI crew foreman, following the

procedures his company had established for such an emergency, informed his supervisor

of the incident. But the supervisor did not immediately notify emergency response

agencies. Instead, he called the Sirti safety coordinator, telling him that he did not know

whom to call. The safety coordinator told him to call NSP and let NSP employees notify

emergency response agencies. The Sirti safety coordinator then departed for the scene.

Along the way, he called Seren management to inform them of the leak. 

By this time, then, several operational and management levels of the involved

companies knew of the leak, yet no one had notified emergency response agencies. In fact,

about 15 minutes elapsed before another individual, not associated with the construction

project, notified emergency responders. The CCI supervisor did eventually call the owner

of the gas line but not until about 30 minutes after the line was struck. By this time, two

NSP employees were already on the scene, the company having been notified by the fire

department dispatcher. 

Had either the crew foreman or his supervisor immediately called 911, responders

could have been on the scene within minutes. For example, a fire department vehicle and

four firefighters were on the scene within about 2 minutes of being notified, but because of

the delayed notification, they arrived some 18 minutes after the rupture and about 21

minutes before the explosion.

Once on scene, the gas technician specialist determined by meter reading that the

gas concentration in Book-Em’s Bar, at 7 percent of LEL, was some 93 percent below the

minimum concentration necessary for an explosion to occur. Because of the proximity of

the leak to the bar, this level could have been the result of gas entry through the door of the

building. According to witness statements, the gas technician specialist left the bar to find

13 National Transportation Safety Board. 1999. Excavation Damage to 20-inch-diameter Buried Steel

Transmission Pipeline, Indianapolis, Indiana, July 21, 1997. Pipeline Accident Brief. Washington, D.C.
Analysis 23 Pipeline Accident Report

the entrance to the basement of the building next door. Before he arrived there, however,

the explosion occurred, and he was killed. With an earlier start to evaluating the risk of the

situation, the gas technician specialist may have been able to determine that gas was, in

fact, accumulating in the basement of the Bellanti’s building. The gas company and

emergency responders may then have decided to evacuate everyone from nearby buildings

and out of the area. Additional steps may have been taken to eliminate ignition sources

and ventilate the basement. In such an event, the explosion may have been prevented or, at

a minimum, some of the people at risk could have been removed from the area.

The Safety Board concludes that had the crew foreman or his supervisor called 911

or the utility owner immediately after the rupture, emergency responders and NSP

personnel may have had time to fully assess the risk and to take actions that could have

helped either to prevent the explosion or to avoid the resulting loss of life.

In 1997, the Safety Board published a safety study that discussed industry and

government actions to prevent excavation damage.14 The study formalized

recommendations aimed at further advancing improvements in excavation damage

prevention programs. One area given prominence was emergency procedures applicable

when a utility is damaged during excavation. The safety study noted that while Federal

regulations require pipeline operators to establish written emergency procedures, the

regulations do not apply to excavators, even though “these are the very people that often

have responsibility for first response at an excavation disaster.” The study concluded that,

at a minimum, “excavators should formulate an emergency response plan appropriate for

the specific construction site and ensure that employees working at that site know the

correct action to take if a buried facility is damaged.” The Safety Board therefore made the

following safety recommendation to the American Public Works Association (APWA):

P-97-30

Develop guidelines and materials that address initial emergency actions by

excavators when buried facilities are damaged and then distribute this information

to all one-call notification centers.

The APWA responded on January 26, 1998, stating that the organization would

like to meet with the Safety Board to discuss the APWA’s ability to implement the safety

recommendations in the package that contained P-97-30. The Board replied on March 12,

1998, placing the recommendations in an “Open—Await Response” status pending the

outcome of a meeting. A meeting was held on March 12, 1998, and the APWA agreed to

look at the package of recommendations and advise the Board regarding which of the

actions the APWA could accomplish. The APWA failed to respond further, and the Safety

Board, in a June 7, 2000, letter, asked the APWA to provide information about its efforts

to implement the safety recommendations. Safety Recommendation P-97-30 remains

classified “Open—Await Response.” 

14 National Transportation Safety Board. 1997. Protecting Public Safety Through Excavation Damage

Prevention. Safety Study NTSB/SS-97/01. Washington, DC.
Analysis 24 Pipeline Accident Report

The safety study also referenced Safety Recommendation P-95-25, issued to the

APWA as a result of the Safety Board’s investigation of a 1993 accident in St. Paul,

Minnesota:

P-95-25

Urge your members to call 911 immediately, in addition to calling the gas

company, if a natural gas line has been severed.

Safety Recommendation P-95-25 has been classified “Closed—Acceptable

Action” based on the fact that the APWA revised its Public Works Practices Manual to

include a chapter on utility coordination that addresses this recommendation. 

Common Ground: The Study of One–Call Systems and Damage Prevention,

15

published in August 1999, provides guidance for saving valuable time in emergency

notification should a natural gas line be damaged during excavation. The “best practice”

regarding contact names and numbers states that

The excavator’s designated competent person at each job site has access to the

names and phone numbers of all facility owner/operator contacts and the one-call

center. 

In the St. Cloud accident, no one at the site had contact names and numbers. Not

even the CCI site project manager had such a list; he told the Sirti safety coordinator that

he did not know whom to call to report the leak. 

The “best practice” statement for notification of emergency personnel is as

follows:

If the protective coating of an electrical line is penetrated or gases or liquids are

escaping from a broken line which endangers life, health or property, the

excavator immediately contacts local emergency personnel or calls ‘911’ to report

the damage location.

The National Utility Locating Contractors Association (NULCA) has developed

guidelines for excavation practices and procedures for damage prevention. The NULCA

guidelines, which were revised in September 1997, include a suggested procedure

whereby excavators call 911 if excavation damage “involves a potential risk to life, health

or significant property damage.”

Both the Common Ground best practice and the NULCA guidelines suggest that a

call to 911 be made only after an excavator determines that excavation damage has

occurred that presents a hazard. Minnesota State law, on the other hand, requires that

15 The Common Ground report was prepared by more than 160 individuals representing a wide range of

interests, organizations, and viewpoints on preventing damage to underground facilities. The project was

initiated by the DOT’s Office of Pipeline Safety, an element of the Research and Special Programs

Administration, in response to the Transportation Equity Act for the 21st Century, Public Law 105-78,

signed into law June 9, 1998. The purpose of the year-long study was to identify and validate existing best

practices performed in connection with preventing damage to underground facilities.
Analysis 25 Pipeline Accident Report

contractors notify 911 in the event of damage to buried utilities if the damage results in the

escape of any flammable, toxic, or corrosive gas or liquid or endangers life, health, or

property. The wording of the Minnesota law relieves excavators of the responsibility of

determining whether damage represents a hazard before they call 911 and the utility

owner. The Safety Board prefers this approach to that of the Common Ground best

practice or the NULCA guidelines. 

In the view of the Safety Board, the utility owner and 911 or other appropriate

emergency notification number should be called any time a hazardous substance is

released from a pipeline through construction damage, regardless of whether those on the

scene perceive an immediate danger to public safety. Excavators are not all

knowledgeable about what constitutes a hazardous situation. For example, they may not

be familiar with the hazards of gas migrating underground, or they may not realize that a

pulled pipeline could be broken in more than one place. Emergency responders can

usually arrive at the scene quickly and are often trained and equipped to assess such

hazards and take appropriate safety measures. 

Strengthened requirements to notify utility owners immediately in the event of any

damage to a pipeline can also increase safety. The sooner the experts from the operator are

notified, the sooner they can apply their knowledge to reduce the public safety risks.

Whereas some contractors may previously have waited until the end of the day to report

damage to pipelines that did not appear to present an obvious threat, requiring immediate

notification of operators could possibly help them prevent a minor problem from

developing into a major hazard. Some damage may not result in an immediate leak but

may represent a hazard in the future. The pipeline operator can determine if corrective

measures are needed to prevent a future failure. If an immediate pipeline leak does occur,

the utility owner is in the best position to be aware of the hazards associated with the

product in its pipelines and the appropriate safety countermeasures, and to be able to

shorten the time until a leak can be stopped. 

Additionally, in the Safety Board’s view, strengthening the notification

requirement will increase awareness on the part of contractors and other excavators of the

importance of taking care not to damage utilities, and a reduction in the number of such

incidents may be expected. 

To help ensure that this issue is addressed on a nationwide basis, the Safety Board

believes that the Occupational Safety and Health Administration (OSHA) at the Federal

level should 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 the meantime, until OSHA can act on this recommendation, the Safety Board

believes that the Path Forward initiative (discussed below in the “Excavation Damage

Prevention” section) should promote the immediate notification of the utility owner and

emergency agencies whenever excavation damage to a utility results in a release of natural

gas or other hazardous substance or otherwise presents a threat to public safety. Because
Analysis 26 Pipeline Accident Report

the DOT’s Research and Special Programs Administration (RSPA) was instrumental in

the creation of the Path Forward initiative, that agency should, through the mechanism of

Path Forward initiative, take the lead in promulgating an industry “best practice” that

advises 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.

To further raise awareness of the early notification issue, the Safety Board believes

the Association of General Contractors, the National Utility Contractors Association, the

Power and Communications Contractors Association, and the National Cable Television

Association should publicize the circumstances of this accident to their memberships to

make them aware of the dangers of damage to an underground utility and the need to

immediately call 911 or other appropriate local emergency response number when a

natural gas leak or other hazardous condition occurs and to immediately notify utility

companies when an underground facility has been damaged.

Fire Department Response

An engine company with a lieutenant and three firefighters arrived within minutes

of fire department notification. Firefighters attempted to take gas concentration readings

with a gas monitor, but the monitor had not been calibrated in fresh air and gave invalid or

unreliable readings. Firefighters continued to attempt readings with the improperly

calibrated instrument, all the while working in an environment in which they described the

gas smell as “pretty bad.” At no point did firefighters check buildings near the leak site to

determine if natural gas was accumulating or to help assess the need for a possible

evacuation, even though the gas line was continuing to release gas that could migrate

through the ground and into nearby buildings, where it could present a danger of

explosion. Two of the firefighters near the leak site returned to their truck as soon as two

gas company employees arrived. It should have been obvious to the firefighters that a

threat continued to exist and that the situation could worsen. 

The Safety Board therefore concludes that firefighters of the St. Cloud Fire

Department responded quickly to the scene of the leak; however, once on the scene, the

firefighters’ actions did not fully address the risk to people and property posed by the leak

or reduce the consequences of a possible fire or explosion.

As part of its postaccident activities, the St. Cloud Fire Department developed

guidelines for natural gas emergency response that address the issues identified in this

accident. According to fire department officials, revisions to procedures have been

developed that should help prevent a similar accident in the future in the St. Cloud Fire

Department’s response area. In the view of the Safety Board, all first responders should be

prepared to respond effectively to a gas leak hazard. 
Analysis 27 Pipeline Accident Report

Timely, effective response to a natural gas emergency can save lives. In an

October 30, 1998, accident in Chicago, Illinois, excavation work damaged a 24-inchdiameter natural gas main.16 The natural gas ignited about 40 minutes later, causing major

fire and heat damage to a nearby 15-story high-rise apartment building. Responding fire

and police personnel completely evacuated the high-rise building before the gas ignited,

with the result that no one was injured in the accident. 

The Safety Board believes that the International Association of Fire Chiefs should

publicize the circumstances of the St. Cloud, Minnesota, accident to their membership to

make them aware of the potential dangers of gas migrating into buildings from damaged

underground gas lines. The Safety Board further believes that the association should

advise its membership of the need to determine the hazards posed by natural gas leaks and

the value of having an evacuation plan in place to be used when the situation warrants.

Excavation Damage Prevention 

The Safety Board has long been concerned about the numbers of accidents

attributable to excavation damage. In May 1997, the Safety Board added excavation

damage prevention to its “Most Wanted” list of safety improvements.17 Data maintained

by RSPA indicate that damage from outside force is the leading cause of leaks and

ruptures to pipeline systems, accounting for more than 40 percent of reported failures.

Investigation of the St. Cloud accident alone revealed a high incidence of excavation

damage to utilities, by different contractors, both before and after the accident. 

A 1994 workshop sponsored jointly by the Safety Board and RSPA brought

together about 400 people representing pipeline operators, excavators, trade associations,

and local, State, and Federal government agencies to identify and recommend ways to

improve prevention programs. The Safety Board’s 1997 safety study was initiated to

analyze the findings of the 1994 workshop, to discuss industry and government actions

undertaken since the workshop, and to make recommendations to further reduce

excavation damage accidents. 

The safety study addressed employee qualifications and training, which has been

an issue in a number of excavation-caused pipeline accidents. To address training and

qualifications of those not covered by Federal regulations, the Safety Board, on January 6,

1998, issued the following safety recommendation to the APWA:

16 Illinois Commerce Commission, September 1999, Report of the ICC Staff: Incident at 1507 North

Claybourn Avenue, Chicago, Illinois, October 30, 1998.

17 In October 1990, the Safety Board developed the “Most Wanted” list, drawn up from previously issued

safety recommendations, to bring special emphasis to the safety issues the Board deems most critical. The

Most Wanted list is updated as needed.
Analysis 28 Pipeline Accident Report

P-97-29

Review existing training programs and materials related to excavation damage

prevention and develop guidelines and materials for distribution to one-call

notification centers.

This recommendation has the same history as Safety Recommendation P-97-30,

discussed earlier, and is classified “Open—Await Response.”

The safety study noted the progress that had been made since 1994 by RSPA and

the industry in the area of improving excavation damage prevention programs. But the

study concluded that despite improvements in State excavation damage prevention

programs, additional efforts were needed to uniformly develop and implement programs

that are most effective. On January 6, 1998, the Safety Board therefore addressed Safety

Recommendation P-97-15 to RSPA and P-97-25 to APWA asking that the two

organizations work in conjunction to:

P-97-15 and -25

Initiate and periodically conduct...detailed and comprehensive reviews and

evaluations of existing State excavation damage prevention programs and

recommend changes and improvements, where warranted, such as full

participation, administrative enforcement of the program, pre-marking

requirements, and training requirements for all personnel involved in excavation

activity.

Based on an October 30, 1998, RSPA response to Safety Recommendation

P-97-15 and on a meeting of representatives from RSPA and the Safety Board to discuss

ongoing actions to address the intent of the recommendation, Safety Recommendation

P-97-15 was classified “Open—Acceptable Response” on June 29, 1999. 

In an April 24, 2000, letter to the Safety Board, RSPA responded in general terms

to 29 Safety Board recommendations, including P-97-15. The letter outlined the agency’s

efforts to create a “self-sustaining private sector non-profit organization” that would

“provide an effective forum for information sharing among all stakeholders in damage

prevention.” These efforts, known as the “Damage Prevention: Path Forward” initiative,18

are intended to continue the efforts begun with the Common Ground study and to address

the issues involved in preventing outside force damage to the underground infrastructure.

Working committees having been established to direct the formal establishment of the

Path Forward program. The Safety Board is encouraged by the promise of the Path

Forward program and will follow the development of the program with interest. The

classification for P-97-15 will remain “Open—Acceptable Response” pending further

action by RSPA.

The Board is also disappointed by the lack of response from the APWA to Safety

Recommendation P-97-25. That recommendation has followed the same history as Safety

18 A new nonprofit organization, the Common Ground Alliance, is being formed to continue the Path

Forward initiative. 
Analysis 29 Pipeline Accident Report

Recommendations P-97-29 and -30, discussed earlier, and remains classified “Open—

Await Response.”

Excess Flow Valves

Excess flow valves (EFVs) are available that respond to an excessive flow of gas

by automatically closing and restricting the gas flow. EFVs therefore can greatly reduce

the consequences of service line ruptures. 

The Safety Board initially advocated using EFVs on service lines to schools and

other buildings in which large numbers of people gather. Later, because EFVs became

cheaper and more available, the Safety Board began advocating the installation of EFVs

on new or renewed residential service lines. During the 1980s, RSPA, which has oversight

responsibilities over the pipeline industry, failed to require EFVs. Consequently, the

Safety Board included the use of EFVs on its 1990 list of Most Wanted safety

improvements.

On September 26, 1990, as a result of its investigation of five natural gas accidents

in the Kansas City-Topeka area, the Safety Board recommended that RSPA:

P-90-12

Require the installation of excess flow valves on new and renewed single-family,

residential high pressure service lines which have operating conditions compatible

with the rated performance parameters of at least one model of commercially

available excess flow valve.

On April 4, 1995, RSPA notified Congress by letter that it had decided not to

require universal installation of EFVs and instead would issue performance standards and

customer-notification requirements for EFVs. In a September 28, 1995, letter to RSPA,

the Safety Board expressed its disappointment with this decision. The Board noted the

continued strong evidence that a way was needed to quickly restrict the flow of gas to a

failed pipe segment. On September 28, 1995, as a result of RSPA’s failure to issue EFV

requirements, the Safety Board classified Safety Recommendation P-90-12 “Closed—

Unacceptable Action.”

On March 6, 1996, as a result of its investigation of a June 9, 1994, natural gas

explosion in Allentown, Pennsylvania, the Safety Board wrote to the governors of all

50 States and to the mayor of the District of Columbia asking that they require gas

distribution operators to install EFVs in all new or replaced gas service lines when

operating conditions are compatible with commercially available valves (Safety

Recommendation P-96-3). Of the States that replied, most advised that they intended to

follow the lead of RSPA and had no plans to require the installation of EFVs. The State of

Minnesota did not respond to Safety Recommendation P-96-3.
Analysis 30 Pipeline Accident Report

Also on March 6, 1996, the Safety Board recommended that RSPA:

P-96-2

Require gas distribution operators to notify all customers of the availability of

excess flow valves; any customer to be served by a new or renewed service line

with operating parameters that are compatible with any commercially available

excess flow valve should be notified; an operator should not refuse to notify a

customer because of the customer’s classification or the diameter or operating

pressure of the service line. 

On February 3, 1998, RSPA issued its final rule regarding EFVs. The rule requires

gas distribution operators either to install EFVs on new or replaced single-residence

service lines expected to operate continuously at not less than 10 psig or to inform

customers of the availability and benefits of EFVs and install them if the customer agrees

to pay for their installation and maintenance. 

On October 6, 1998, the Safety Board classified this recommendation “Closed—

Unacceptable Action,” in part because the RSPA rule limits required notifications by gas

operators to residential customers. As in the case in the St. Cloud accident, many

commercial service lines have operating characteristics compatible with the same EFVs

that will be installed in residential service lines.

According to an American Gas Association survey, since the issuance of the RSPA

final rule on EFVs, approximately one-half of the operators of gas distribution systems

have elected to install EFVs, and one-half have developed procedures to inform customers

of their availability. NSP’s current policy, put in place after the St. Cloud accident, is to

install EFVs on all new or replaced service lines that fit the operating requirements of its

approved EFVs, regardless of whether the customer is residential or commercial.

Because no further action can reasonably be expected to be taken either by RSPA

or the States, the Safety Board, on May 3, 2000, removed the recommendations regarding

EFVs from its Most Wanted list. In a July 5, 2000, letter to the Governor of Minnesota, the

Safety Board asked for information about Minnesota’s intentions with respect to Safety

Recommendation P-96-3. Until Minnesota responds to the Safety Board’s latest request

for information, Safety Recommendation P-96-3 to the State of Minnesota will be

classified “Open—Unacceptable Action.” 

When NSP converted the gas service line from low pressure to high pressure, the

line itself was not replaced; therefore, the most recent Safety Board recommendations

regarding EFVs would not have applied to this service line. Nonetheless, the Safety Board

is convinced of the usefulness of EFVs in preventing pipeline accidents and concludes that

had the gas line in this accident been equipped with an EFV, the valve may have closed

after the pipeline ruptured and the explosion may not have occurred.
31 Pipeline Accident Report

Findings

Conclusions

1. The marked location of the ruptured gas line was accurate and was therefore not a

factor in this accident.

2. While the toxicological testing performed after this accident was not useful for

determining whether alcohol or drugs had any influence on the performance of the

Cable Constructors, Inc., crewmembers while they were installing the anchor, the

crewmembers’ actions before and after the rupture indicate that they were likely not

impaired by alcohol or drugs at the time of the accident.

3. Cable Constructors, Inc.’s anchor installation procedures were inadequate in that they

did not address steps to take under unusual circumstances (such as striking a

significant underground obstacle) to ensure that buried utilities were protected during

the entire installation process, including the underground portion.

4. Had the crew foreman or his supervisor called 911 or the utility owner immediately

after the rupture, emergency responders and Northern States Power personnel may

have had time to fully assess the risk and to take actions that could have helped either

to prevent the explosion or to avoid the resulting loss of life.

5. Firefighters of the St. Cloud Fire Department responded quickly to the scene of the

leak; however, once on the scene, the firefighters’ actions did not fully address the

risk to people and property posed by the leak or reduce the consequences of a possible

fire or explosion.

6. Had the gas line in this accident been equipped with an excess flow valve, the valve

may have closed after the pipeline ruptured and the explosion may not have occurred.

Probable Cause

The National Transportation Safety Board determines that the probable cause of

this accident was the lack of adequate procedures by Cable Constructors, Inc., to prevent

damage to nearby utilities when its anchor installation crews encountered unusual

conditions such as striking an underground obstacle. Contributing to the severity of the

accident was the delay by Cable Constructors, Inc., in notifying the proper authorities. 
32 Pipeline Accident Report

Recommendations

New Recommendations

As a result of its investigation, the National Transportation Safety Board makes the

following safety recommendations:

To the Research and Special Programs Administration:

Through the mechanism of the Path Forward initiative, take the lead in

promulgating an industry “best practice” that advises 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. (P-00-1)

To the Occupational Safety and Health Administration:

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.

(P-00-2)

To the Associated General Contractors of America: (P-00-3 and -4)

To the National Utility Contractors Association: (P-00-5 and -6)

To the Power and Communications Contractors Association: (P-00-7 and -8)

To the American Public Works Association: (P-00-9 and -10)

To the National Cable Television Association: (P-00-11 and -12)

Inform your membership of the circumstances surrounding the December

11, 1998, accident in St. Cloud, Minnesota, to make them aware of the

dangers of damage to an underground utility and the need to immediately

call 911 or other appropriate local emergency response number when a

natural gas leak or other hazardous condition occurs and to immediately

notify utility companies when an underground facility has been damaged. 
Recommendations 33 Pipeline Accident Report

Advise your membership to review and revise their anchor installation

procedures as necessary to ensure that safety margins around buried

utilities are absolutely observed not only above ground but throughout the

installation process.

To the International Association of Fire Chiefs:

Inform your membership of the circumstances surrounding the December

11, 1998, accident in St. Cloud, Minnesota, to make them aware of the

potential dangers of gas migrating into buildings from damaged

underground gas lines. Advise your membership of the need to determine

the hazards posed by natural gas leaks and the value of having an

evacuation plan in place to be used when the situation warrants. (P-00-13)

Previously Issued Recommendations 

Classified in this Report

The following previously issued safety recommendations are classified in this

report:

To the Research and Special Programs Administration:

Initiate and periodically conduct, in conjunction with the American Public

Works Association, detailed and comprehensive reviews and evaluations

of existing State excavation damage prevention programs and recommend

changes and improvements, where warranted, such as full participation,

administrative enforcement of the program, pre-marking requirements, and

training requirements for all personnel involved in excavation activity.

(P-97-15)

Safety Recommendation P-97-15 (previously classified “Open—Acceptable

Response”) is again classified “Open—Acceptable Response” in the “Excavation Damage

Prevention” section of this report.

To the State of Minnesota:

Require gas distribution operators to install excess flow valves in all new

or renewed gas service lines, when operating conditions are compatible

with commercially available valves, including service lines supplying

schools, churches, and other places of public assembly. (P-96-3)

Safety Recommendation P-96-3 (previously classified “Open—Await Response”)

is classified “Open—Unacceptable Action” in the “Excess Flow Valves” section of this

report. 
Recommendations 34 Pipeline Accident Report

BY THE NATIONAL TRANSPORTATION SAFETY BOARD

JAMES E. HALL

Chairman

JOHN A. HAMMERSCHMIDT

Member

JOHN J. GOGLIA

Member

GEORGE W. BLACK, JR.

Member

CAROL J. CARMODY

Member

Adopted: July 11, 2000