Oroville Dam Emergency: How Civil Engineering Failures Advance the Industry
By Ryan Ayers
Disasters and infrastructure failures force us all to take a step back and think about what we're doing to prevent damage and the loss of life when we build bridges, dams, and other necessary structures. Of course, no structure is perfect, but civil engineers are always working to build better, safer, and more efficient structures that can live up to the demands of heavy use. The Oroville Dam, built in the 1960s, is the tallest dam in the United States at 770 feet tall. The dam's purpose is threefold: water supply, flood control, and hydroelectricity. Recently, however, a structural emergency rendered the Oroville Dam a potential threat to residents, rather than an essential structure intended to make life easier and more efficient.
The Oroville Emergency
In mid-February of 2017, the Oroville Dam started to show signs of major trouble during heavy storms. A hole in the never-used emergency spillway opened up, and with it, the potential for massive flooding as lake levels rose. The concrete structure had been eroded, a dangerous situation during the rainy season in Oroville, when the spillways are most likely to see use. 188,000 people were forced to leave their homes and the nearby area, as water was already starting to spill over into the emergency chute. A race to leave the area commenced, with traffic jams spreading out in all directions from Oroville.
During the rainy season, Lake Oroville's levels are much higher than normal, and the water had already begun to spill over into the emergency spillway. Officials sprang into action to minimize damage, reducing the flow of water into the emergency spillway to reduce damage, while still working to lower the lake's water levels. However, a large hole about 300 feet wide and 500 feet long opened up along the chute due to erosion. The emergency spillway had never been used before, but the amount of storm water coming down from the mountains was strain on the structure in a time of need.
Luckily, efforts to reduce the water level paid off, and the lake level was dropped in anticipation of upcoming storms. Erosion in the spillway still caused major concern, however, and the nearby power plant stopped functioning temporarily due to the spillway debris. Engineers began to assess the damage and remove some of the detritus from the spillway.
The good news about the Oroville Dam emergency is that it could have been much worse. The dam held, and massive flooding was averted. The power plant associated with the dam will likely reopen soon. However, the disaster does highlight the fact that much of our country's infrastructure is outdated, or in poor condition. White House Press Secretary Sean Spicer commented on Oroville by highlighting the problems that can be seen all over the country:
"The situation is a textbook example of why we need to pursue a major infrastructure package in Congress....Dams, bridges, roads and all ports around the country have fallen into disrepair."
Now, engineers have an opportunity to take a hard look at the Oroville Dam and figure out what went wrong. How can the structure be repaired and improved to prevent future trouble? These are just some of the questions civil engineers will be exploring in the coming weeks and months to prevent another disaster the next time heavy rains roll in.
Past Disasters-and What We've Learned
Spicer's comment brings up a major issue in this country: the soundness and maintenance of our infrastructure. This isn't the first time a major disaster as emerged thanks to flaws in infrastructure and engineering, and it won't be the last. However, there is a silver lining to the Oroville disaster and others like it: an opportunity to learn and improve upon past designs. There is enormous precedent for this, with at least 5 other disasters leading to improvements and breakthroughs in engineering and technology:
- The St Francis Dam, 1928. The dam failed and flooded the San Francisquito Canyon and killing 600. This prompted new legislation in dam safety standards, and California inspected and repaired their existing dams.
- The Tacoma Narrows Bridge, 1940. The 3rd largest suspension bridge, "Galloping Gertie" began to "gallop", then broke apart. A new design that was better able to handle the wind was put into place-"Sturdy Gertie", which still stands today.
- The New Orleans Hurricane Protection System, 2005. Hurricane Katrina devastated the levees and floodwalls, resulting in over a thousand deaths and $21 billion in residential property damage. After the disaster, new flood control systems were introduced, making it the best flood control system of any US coastal city. Anticipates storms even larger than Katrina.
- Quebec Bridge, 1907 and 1916. The first bridge was structurally unsound, causing the deaths of 86 workers and prompting an overhaul. The second bridge was much heavier and collapsed again, killing 13. The final redesign used nickel alloy steel that was much stronger than carbon steel.
- Ronan Point Apartment Tower, 1968. This London apartment building used a fast, cheap panel system that should never have been used for a building of this height. During a gas leak, there was an explosion, and the lack of structural support cause 4 floors to collapse, killing 4 people. From this disaster, building codes in both parts of Europe and the US to protect people from shoddy construction.
All of these disasters, while tragic, have helped progress infrastructure to become safer and more efficient over time.
What Do Engineering Disasters Accomplish?
In the case of the Oroville Dam, no one was hurt and no property damage occurred during its failure. We now have an opportunity to reassess the form and function of this important structure. Although any disaster is tragic, engineering failures have played a pivotal part in advancing the civil engineering industry and developing new technologies.