Safety Culture Communicator

Case Study 3 September 2011

Partial Collapse of the Willow Island Cooling Tower

PURPOSE

This case study is intended to provide a useful 

tool for the U.S. Nuclear Regulatory Commission 

(NRC) staff as it interacts with their stakeholders. 

It will also enable the regulated community to 

identify with, and learn from, the findings made 

by the West Virginia Governor’s Commission on 

Willow Island and the Occupational Safety and 

Health Administration (OSHA). The safety culture 

traits that the NRC has incorporated into its recent 

Safety Culture Policy Statement can be applied to 

these findings. 

This case study describes the safety culture 

shortcomings that led directly to the partial 

collapse of a natural draft, hyperbolic, reinforced 

concrete cooling tower at Willow Island, WV, on 

April 27, 1978. The cooling tower was one of two 

towers being constructed by Research-Cottrell, 

Inc., for the Pleasants Power Station, a coal-fired 

electric power station owned by Allegheny Energy 

Supply Company. The resulting deaths of 51 

construction workers represent one of the most 

costly accidents, in human terms, of any in the U.S. 

construction industry’s history.

WHAT HAPPENED?

A post accident report by the Center for Building Technology, National Engineering Laboratory, 

National Bureau of Standards,1 describes the accident as follows:

The shell [of the cooling tower] was constructed through the use of a patented lift form technique.2 Except for the lower and upper portions 

of the tower, the construction procedure at Willow Island utilized a scheme to place a 5-ft (1.5-m) lift per day. At the time of failure, 28 lifts 

had been completed with the most recent one having been placed the previous day. The form work which supported the less than one day 

old concrete of lift 28 had been raised into place for lift 29. According to eyewitness accounts by workers, lift 28 began to collapse when the 

third bucket of concrete was being hoisted up to the working platform... According to eyewitnesses, the entire section of lift 28 collapsed 

into the tower [falling approximately 170 feet] within a few minutes.

Following the accident, the State of West Virginia commissioned a study of the accident.3 OSHA 

commissioned a report prepared by the National Bureau of Standards as described in footnote 1 and 

in a second report.4 

PROBABLE CAUSE

• The concrete that supported the lift form-work scaffolding system was of insufficient compressive strength to support the loads to which it was 

being subjected. The concrete had been placed only 18 hours before being required to support the lift form-work scaffolding system and had a 

predicted compressive strength of 220 pounds per square inch (psi) as noted in NBSIR 

80-2010.4 As further noted, the concrete would have started to fail at a compressive 

strength of 1,000 psi. In addition, the required concrete strength to support the lift 

form-work system should have included a factor of safety of 2 and consideration of the 

dynamic effects of the hoisting loads.

• The anchor point for the static line that was used by the hoisting system for lifting 

concrete was moved from a point on the ground near the cooling tower wall to a point 

on the ground at approximately the center of the cooling tower. The anchor point 

is routinely moved because of the changing geometry of the ongoing construction.5 

NBSIR 80-2010 concludes, “If the base anchor point of the static line had been kept at 

its previous location (before the last move to near the center of the tower), the effects of 

the construction loads would have been reduced to such an extent that failure of lift 28 

of the tower would probably not have occurred.”

1. H.S. Lew, et al., “Investigation of the Construction Failure of Reinforced Concrete 

Cooling Tower at Willow Island, West Virginia,” NBSIR-1578, Center for Building 

Technology, National Engineering Laboratory, National Bureau of Standards, 

November 1979.

2. The lift form-work scaffolding system was a complex structure containing the 

concrete forms, scaffolding, and a hoisting system for lifting concrete up to the pour 

site. The lift form-work scaffolding system structure contained a hydraulic jacking 

frame so that the entire structure could be lifted up in preparation for placing a new 

circular ring section of the cooling tower. Once the form-work scaffolding was 

lifted up, it was secured into the most recently placed concrete.

3. “Governor’s Commission on Willow Island—Report to the Governor and Legislature,” 1980.

4. H.S. Lew and S.G. Fattal, “Analysis of Construction Conditions Affecting the 

Structural Response of the Cooling Tower at Willow Island, West Virginia,” NBSIR 

80-2010, July 1980.

5. Norbert J. Delatte, Jr., “Beyond Failure—Forensic Case Studies for Civil Engineers,” 

ASCE Press, 2009.

Forms

Forms

Lift form-work 

scaffolding system

Static line to 

anchor point

Concrete

Bucket

Cathead 

Gantry

Concrete

Perspective of Scaffolding System (NBS Rpt, 1979)
NRC Positive Safety Culture Traits

Leadership Safety Values and Actions in which 

leaders demonstrate a commitment to safety in their 

decisions and behaviors.

Work Process in which the process of planning and 

controlling work activities is implemented so that 

safety is maintained.

Problem Identification and Resolution in which 

issues potentially impacting safety are promptly 

identified, fully evaluated, and promptly addressed 

and corrected commensurate with their significance.

Continuous Learning in which opportunities to learn 

about ways to ensure safety are sought out and 

implemented.

Evidence of Weak Safety Culture Traits

It appears that no one was responsible for process safety at Willow Island. The 

Governor’s Commission on Willow Island Report found that “...there were no 

inspectors or supervisors of any kind on the job whose responsibility it was to check 

the work to make the determination either to proceed with the work or give the 

concrete more time to gain strength.”

Given that the lift form-work scaffolding system was anchored in the previously poured 

concrete and had no other means of support, the strength of the supporting concrete 

was crucial. However, the contractor never established, or questioned, the strength 

of the supporting concrete. As noted in the Governor’s Commission on Willow Island 

report, “Although Pittsburgh Testing Laboratories personnel tested the concrete, it was 

not necessarily done before the framework was removed, and nothing in their contract 

would seem to indicate they would have any authority to shut the job down if they found 

problems.” OSHA issued Research-Cottrell “...a citation alleging a willful violation [an 

intentional and knowing violation] for failure to make field tests on field-cured concrete 

specimens to insure that the concrete had attained sufficient strength to safely support 

the load prior to removal of the forms.”6

There appeared to be no formal training program for workers. The Governor’s 

Commission on Willow Island report found that “Because of the word-of-mouth training 

that is a natural part of the work environment and because there were no written 

specifications available for reference, workers could inadvertently make gradual 

modifications that might compromise the design and cause conditions beyond the 

limitations of the materials.”

WHAT CAN ORGANIZATIONS LEARN FROM THIS ACCIDENT?

This accident reinforces the need for, and the importance of, promoting a positive safety culture by routinely evaluating safety culture 

activities and initiatives and making enhancements and adjustments to ensure that an organization remains proactive and appropriately 

focused in this important area. 

Key lessons from this case study are the following:

• Critical safety-related process variables should be identified and controlled. In the case of the Willow Island accident, the strength of the 

supporting concrete and the anchor point for the static line that was used by the hoisting system for lifting concrete were critical safetyrelated process variables; no limitations on these critical safety-related process variables had been established. 

• A decisionmaking process for critical safety-related process variables, based on written procedures, should be established. In the case 

of the Willow Island accident, movement of the lift form-work scaffolding system should have been based on demonstration, via a concrete 

testing program, that the concrete had achieved minimum safety strength. Likewise, movement of the anchor point for the static line that 

was used by the hoisting system for lifting concrete should have been subjected to a careful decisionmaking process.

• The root causes of past incidents should be thoroughly investigated to establish the facts of any safety issue to have an overall 

understanding of the event and to take necessary actions to prevent recurrence. The lessons learned from the root cause analysis should be 

used to establish corrective actions that apply to a broader set of similar circumstances in other work scenarios. As a result of this incident, 

major industry-wide improvements have been made in the construction of cooling towers and other similar specialty structures.

6. Statement of Dr. Eula Bingham, Assistant Secretary of Labor, Transcript of the House of Representatives Subcommittee on Compensation, Health and Safety, Committee on Education and Labor, June 30, 1978.

Sources of Information:

1. H.S. Lew, et al., “Investigation of the 

Construction Failure of Reinforced Concrete 

Cooling Tower at Willow Island, West Virginia,” 

NBSIR-1578, Center for Building Technology, 

National Engineering Laboratory, National 

Bureau of Standards, November 1979.

2. H.S. Lew and S.G. Fattal, “Analysis of 

Construction Conditions Affecting the Structural 

Response of the Cooling Tower at Willow Island, 

West Virginia,” NBSIR 80-2010, July 1980.

3. “Governor’s Commission on Willow Island—

Report to the Governor and Legislature,” 1980.

4. Transcript of the House of Representatives 

Subcommittee on Compensation, Health and 

Safety, Committee on Education and Labor, 

June 30, 1978.

This Safety Culture Case Study was developed 

by David H. Jaffe on rotational assignment to the 

NRC’s Office of Enforcement. If you have any 

questions, please contact David Solorio, 

Branch Chief, at 301-415-0149 or by e-mail at 

Dave.Solorio@nrc.gov.

Note that the NRC has not conducted a formal analysis 

of the events discussed herein for, or in conjunction 

with, the West Virginia Governor’s Commission on 

Willow Island, OSHA, or any other organization. The 

NRC compiled the factual information presented and 

discussed from publicly available sources, as identified.