Findings of the Oroville Dam Spillway Forensic Investigation: Download

At a height of 770 feet, Oroville Dam is the tallest dam in the United States. On February 7, 2017, a section of the concrete chute slab of the service spillway at Oroville Dam failed during spillway discharge. Several days later, as the California Department of Water Resources was evaluating and managing discharges through the damaged service spillway during a large rainfall event, the emergency spillway activated for the first time in the project’s history. The emergency spillway flow resulted in significant erosion of the hillside below the crest structure, leading to concern for the integrity of the emergency spillway and the evacuation of nearly 190,000 downstream residents. The Federal Energy Regulatory Commission mandated a forensic evaluation of the failure of the service spillway chute and the damage to emergency spillway. This webinar will present the findings of the six-person Independent Forensic Team, including discussions of physical factors, human / organization factors, and lessons to be learned from the incident.

OUTLINE

FINDINGS OF THE OROVILLE DAM SPILLWAY FORENSIC INVESTIGATION

1. Introduction
   1. Purpose of the Investigation
   2. Investigation Team
   3. Investigation Methodology
2. Background Information
   1. Oroville Facility Description
   2. Regulatory Setting
      • i.     Federal Energy Regulatory Commission (FERC)
      • ii.     California Division of Safety of Dams (DSOD)
   3. Spillway Descriptions
      • i.     Service Spillway
      • ii.     Emergency Spillway
   4. Chronology of the February 2017 Incident
   5. Service Spillway Chute Design and Construction
   6. History of Service Spillway Chute Repairs
   7. History of Service Spillway Drain Flows
3. Question Period #1
4. The Physics of What Happened
   1. Service Spillway
   2. Emergency Spillway
5. Question Period #2
6. Why Was This Performance Unexpected
   1. History of Inspections and Regulatory Setting
   2. Geological Evaluations
   3. Chute Slab Repairs
   4. Potential Failure Mode Analyses (PFMAs)
   5. Activation of the Emergency Spillway
   6. Conclusions
7. Lessons to be Learned