3.1 Oroville Dam Spillway Accident
25
A summary of its key findings, with particular attention to risk identification and
risk informed decision-making are presented in what follows.
3.1.2 The IFT Report
Summary
The “Independent Forensic Team Report—Oroville Dam Spillway Incident, January
5, 2018” (IFT Report 2018) provides an excellent analysis of not only the geotechnical physical aspects of the incident but also of the human, organizational and industry
factors that created the hazards that existed at the time of the incident. In the introductory summary of the report it stated that “…the incident was caused by a complex
interaction of relatively common physical, human, organizational, and industry factors, starting with the design of the project and continuing until the incident”.
The main physical factors related to the failure of the spillways systems are
described as being related to “unrecognized inherently weak design and as-built
conditions affecting the initial failure area” and “unrecognized poor foundation conditions incompatible with design.” It was noted that flowing water resulted in uplift
forces beneath the service spillway chute slab that exposed the underlying poor quality foundation rock to unexpected severe erosion, resulting in removal of additional
slab sections and more erosion. For the emergency spillway, the report states that
the principal physical factor contributing to the damage was clearly the presence of
significant depths of erodible soil and rock in features orientated in a manner that
allowed rapid erosion toward the crest control structure. Details can be found in
Chap. 4, “The Physics of What Happened”, of the IFT Report.
The question of why and how the owner, regulator and industry practices failed to
prevent the incident forms a very valuable part of the IFT’s deliberations. The human,
organizational and industry factors that led to important risks not being recognized
and addressed are described in Chap. 5, “Why the Incident Happened” and Chap. 6,
“General Organizational, Regulatory, and Industry Factors”. The following sections
in this chapter will build on the findings of the IFT Report Summary and Chap. 7,
“Lessons To Be Learned,” as they apply to risk identification and risk management
from an industry perspective.
What the IFT Learned
While not stated as a lesson to be learned, the most important observation of the IFT
team was that human judgments, decisions, actions and inactions can be significant
contributing factors in creating the conditions that allow a system failure to occur.
Understanding a failure or incident from the standpoint of the physical factors and
mechanisms that were involved is a necessary first step but the IFT believes that it is
only the starting point of a process that must lead to an analysis of why those factors
or mechanisms were allowed to exist in the first place. It is for this reason that their
lessons to be learned focus more on management commitment and the decisions
required to translate the highest standards into practice. The IFT notes further that
25
A summary of its key findings, with particular attention to risk identification and
risk informed decision-making are presented in what follows.
3.1.2 The IFT Report
Summary
The “Independent Forensic Team Report—Oroville Dam Spillway Incident, January
5, 2018” (IFT Report 2018) provides an excellent analysis of not only the geotechnical physical aspects of the incident but also of the human, organizational and industry
factors that created the hazards that existed at the time of the incident. In the introductory summary of the report it stated that “…the incident was caused by a complex
interaction of relatively common physical, human, organizational, and industry factors, starting with the design of the project and continuing until the incident”.
The main physical factors related to the failure of the spillways systems are
described as being related to “unrecognized inherently weak design and as-built
conditions affecting the initial failure area” and “unrecognized poor foundation conditions incompatible with design.” It was noted that flowing water resulted in uplift
forces beneath the service spillway chute slab that exposed the underlying poor quality foundation rock to unexpected severe erosion, resulting in removal of additional
slab sections and more erosion. For the emergency spillway, the report states that
the principal physical factor contributing to the damage was clearly the presence of
significant depths of erodible soil and rock in features orientated in a manner that
allowed rapid erosion toward the crest control structure. Details can be found in
Chap. 4, “The Physics of What Happened”, of the IFT Report.
The question of why and how the owner, regulator and industry practices failed to
prevent the incident forms a very valuable part of the IFT’s deliberations. The human,
organizational and industry factors that led to important risks not being recognized
and addressed are described in Chap. 5, “Why the Incident Happened” and Chap. 6,
“General Organizational, Regulatory, and Industry Factors”. The following sections
in this chapter will build on the findings of the IFT Report Summary and Chap. 7,
“Lessons To Be Learned,” as they apply to risk identification and risk management
from an industry perspective.
What the IFT Learned
While not stated as a lesson to be learned, the most important observation of the IFT
team was that human judgments, decisions, actions and inactions can be significant
contributing factors in creating the conditions that allow a system failure to occur.
Understanding a failure or incident from the standpoint of the physical factors and
mechanisms that were involved is a necessary first step but the IFT believes that it is
only the starting point of a process that must lead to an analysis of why those factors
or mechanisms were allowed to exist in the first place. It is for this reason that their
lessons to be learned focus more on management commitment and the decisions
required to translate the highest standards into practice. The IFT notes further that