Ep 39 Lake Peigneur and Cantara Loop
This week's episode features a sneak peek at two of our favourite bonus mini failure episodes.
The first mini failure we are sharing with you is Lake Peignuer in Louisiana (1:55). The entire lake drained into an underground salt mine in a matter of minutes.
And the second Mini Failure is about the Cantara Loop rail disaster (9:40). In the '90s a train derailed into the Sacramento River on a very challenging section of track.
If you like the mini failure episodes you hear today, there are others exclusively available on our Patreon page. For $5/month, less than a pint of beer, you can get access to more of these episodes and you can support our show so we can keep bringing you great content.
Check out our new Patreon page for Mini Failure bonus episodes - https://www.patreon.com/failurology
Sources:
Lake Peigneur
Mine Safety Report - https://babel.hathitrust.org/cgi/pt?id=uc1.31822029061140&view=1up&seq=13&skin=2021
Cantara Loop
Episode Summary
Hi and welcome to Failurology; a podcast about engineering failures. I’m your host, Nicole
And I’m Brian. And we’re both from Calgary, AB.
Today we have a very special episode for you, featuring two of our favourite mini failure episodes. You may have heard us talk about our mini failure episodes before, they are shorter versions of our regular episodes and feature failures with straightforward causes or limited information. We have a list of almost 100 failures that we want to tell you about, but they don’t all fit into the format of our regular episodes.
The first mini failure we are sharing with you is Lake Peignuer in Louisiana. The entire lake drained into an underground salt mine in a matter of minutes. They even caught it on video!
And the second Mini Failure is about the Cantara Loop rail disaster. In the '90s a train derailed into the Sacramento River on a very challenging section of track. In addition to hearing about the failure, you will also hear all about Brian and I’s love for trains. Choo Choo.
If you like the mini failure episodes you hear today, there are others exclusively available on our Patreon page.. For $5/month, less than a pint of beer, you can get access to more of these episodes and you can support our show so we can keep bringing you great content. There is a link to our Patreon page in the show notes for this episode, or you can check out the support page on our website failurology.ca for a link and a list of our current and upcoming bonus episodes. So without further adieu, here are the mini failures.
Lake Peigneur Notes
Hi and welcome to Failurology; a podcast about engineering failures. I’m your host, Nicole. And I’m Brian. And we’re both from Calgary, AB. Welcome to our first mini failure episode. We’re bringing you engineering failures in bite-size pieces. Make no mistake, these are still significant failures, but they either have pretty straightforward causes or not enough information available for a full episode. Essentially, we have a list of failures we want to tell you about but haven’t been able to dig up enough info to talk about them for 45 minutes. These episodes are also just the failure, no news and no ads (for now at least). It’s like Failurology-lite.
This week’s mini failure is about Lake Peigneur in Louisiana.
I am so fascinated with this story, this is a really impressive failure. An entire lake drained into a salt mine in a matter of minutes. They even caught it on video.
It used to be a 3m deep freshwater lake
But on Nov 20th, 1980, a man-made disaster changed the lake and its shores.
The water is now brackish, with a depth of 60m. It’s the deepest lake in Louisiana.
Diamond Crystal Salt Company salt mine under the water had been mining salt since 1919.
Texaco oil rig (contracted out to Wilson Brothers) was doing exploratory drilling above the mine at the time.
350mm drill bit because stuck 2.5 hrs before
It’s believed that the drill punctured the roof of the mine and the entire lake drained into the salt mine
All evidence to identify the cause was washed away. But the engineers from Texaco and Diamond Crystal worked together and were able to estimate the approximate location.
As the water drained into the salt mine, the hole got bigger and bigger.
The drilling platform, 11 barges, a tugboat, many trees, ¼ square km of lakeshore drained into the mine.
The lake usually drained into Vermillion Bay, but so much water drained into the mine that the flow reversed and reversed the flow, bringing saltwater from Vermillion Bay into Lake Peigneur
This created the tallest waterfall ever in Lousiana at 50m as the lake refilled
The air in the mineshafts erupted as compressed air and then 120m tall geysers
No humans died, but 3 dogs did. That’s really sad.
All 55 employees at the mine escaped.
All 7 crew on the drilling rig fled
And a fisherman who was on the lake escaped
Once the pressure equalized, nine of the eleven barges swallowed up by the mine popped out the whirlpool.
Texaco and Wilson Brothers paid $32 million to Diamon Crystal and $12.8 million to Live Oak Gardens (a nearby botanical garden and plant nursery) in out of court settlements
The mine was officially closed in 1986.
Since 1994, AGL resources have used the salt dome as a storage and hub facility for pressurized natural gas. The locals are not thrilled about this.
The Mine Safety and Health Administration released a report on the incident in August 1981 which documented everything but didn’t note a specific cause. Here are the possible causes.
The mining operation experienced subsidence on the surface and stress change underground. This was monitored since the early 70s. A 1971 engineering study stated, “the entire structure of the salt dome is not stable”. Although there was no visible structural failure witnessed during inspections, it’s possible that a weakened structure developed into catastrophic failure as mining continued.
The drilling rig became stuck 2.5 hrs before the failure which resulted in a loss of circulation of drilling mud and the continued management of pressure. If you want more info on drilling rigs and how they use drilling mud to manage pressure at the wellhead, check out episode 25 of Failurology. We covered the Deepwater Horizon disaster and included an overview of how rigs work.
So there you have it, an entire lake drained into a salt mine in a matter of minutes.
Thanks for listening to this mini-failure episode. For our regular episodes, check out Failurology wherever you get your podcasts. If you want to chat with us, our Twitter handle is @failurology, you can email us at thefailurologypodcast@gmail.com, or you can connect with us on Linked In. there are links to all of these in the show notes. Bye everyone, talk soon!
Cantara Loop Notes
Hi and welcome to Failurology; a podcast about engineering failures. I’m your host, Nicole. And I’m Brian. And we’re both from Calgary, AB. Welcome to our fourth mini-failure episode. We’re bringing you engineering failures in bite-size pieces. Make no mistake, these are still significant failures, but they either have pretty straightforward causes or not enough information available for a full episode. Essentially, we have a list of failures we want to tell you about but haven’t been able to dig up enough info to talk about them for 45 minutes. These episodes are also just the failure, no news and no ads (for now at least). It’s like Failurology-lite.
This week’s mini failure is about the Dunsmuir Rail Disaster
On July 14, 1991, a Southern Pacific train derailed into the upper Sacramento River at a horseshoe curve of track known as the Cantara Loop, just north of the town of Dunsmuir, California.
Several of the derailed cars made contact with the water, including a tank car. But they didn’t know what was in it at the time. Spoiler alert, it’s bad. Like really, really bad.
By the morning of July 15, it was apparent that the tank car had ruptured and spilled its entire contents into the river. This was approximately 70,000 litres of the soil fumigant metam sodium; which is a biocide that pretty much kills any living thing.
Route
The train route goes past one of the tallest volcanic peaks in the US, Mount Shasta
To avoid building and operating a track in mountainous terrain, the train route went down into the Sacramento River valley
Getting trains in and out of the valley was one of the biggest design challenges engineers faced. In order to overcome the steep slope, the track has two switchbacks in it. Heading uphill, the first is the Cantara Loop which is located right at the Sacramento River crossing and is the location of this failure. And the second is the Sawmill Curve which is less sharp, still challenging but less so than Cantara and is located near the highway.
The Cantara loop is one of America’s most challenging sections of rail track with a curvature of 14 degrees and a curve radius of 125m.
It’s so challenging in fact that trains require extra locomotives to overcome gravity as they climb out of the Sacramento River valley. They house these extra locomotives 8km south of the loop
The train that derailed was 1,800 m long train with 97 cars; 11 loaded cars and 86 empties for a total weight of 4,294 tons. It was travelling north up the canyon from San Francisco to Portland
At 9:40 pm as the train was approaching the Cantara loop, the lead locomotive and the 7 cars behind it derailed into the Sacramento River. One of those was the tank car Brian mentioned earlier.
The derailment was ultimately caused by the configuration of the train. There were too many empty, light cars at the front, with the heavy cars at the back of the train. This led to a string lining effect where the forces of the heavy front and rear sections of the train tugged away from each other, causing the lighters cars in the middle to come off the tracks to form a straight line between both ends. Like taking two ends of a piece of string and pulling them tight. Except for the middle of the string is a train that is crossing a river.
There was also a problem with the lead locomotive. It hadn’t been working properly and had been surging and jerking. The surging was happening as the train went into the curve, which also added to the risk of string lining.
To prevent this type of derailment from happening again:
a barrier was built to prevent string lined trains from falling into the river
Regulations were added on train configuration to prevent string lining in the first place
And regulations were added to reduce the length of trains, reduce speed, and upgrade locomotives pulling the train
Metam Sodium
So we know the train derailed and one of the tank cars landed in the river. But it’s so much worse than that. As I mentioned earlier, the tank car was filled with Metam Sodium, which is a potent herbicide and pesticide most commonly used to sterilize the soil for agricultural purposes. When mixed with water, metam sodium breaks down into several highly toxic compounds. These chemical compounds have varying toxicities and half-lives in the aquatic environment. Though some are highly toxic, all dissipate in a matter of hours or weeks and do not linger long-term
When the train derailed and the metam sodium started leaking into the river, it turned a greenish-brown colour; where it was normally clear. And it took nearly 3 days before scientists were even allowed near the water. That’s how toxic this stuff is.
Travelling at just under one mile per hour on average, the chemical plume entered Shasta Lake, 66km away from the Cantara Loop, on the morning of 17 July 1991. At the lake, representatives from the Environmental Protection Agency (EPA), Department of Water Resources, and Southern Pacific, the rail line that was operating the derailed train, got to work cleaning up the mess. Dilution and evaporation of the metam sodium, combined with continued aeration, reduced the chemical to undetectable levels in the lake by 29 July 1991. Two weeks later after the derailment.
But by that time, over a million fish, and tens of thousands of amphibians and crayfish were killed. Millions of aquatic invertebrates, including insects and mollusks, which form the basis of the river's ecosystem, were destroyed. Hundreds of thousands of willows, alders, and cottonwoods eventually died. Many more were severely injured.
The Upper Sacramento River is now largely recovered from the spill though some species such as crayfish and frogs have not yet come back. The watershed is carefully stewarded by The Upper Sacramento River Exchange. The popular fishery is again healthy. Recent changes to angling regulations have opened the Upper Sacramento River to catch-and-release fishing all year round. Five-pound trout have often been caught right in the city.
So there you have it, the Dunsmuir rail disaster, which still ranks as the largest hazardous chemical spill in California. Take that Erin Brokovich. Oooo I love that movie. Luckily, most species have completely recovered now after a 3-year fishing ban. It’s also nice to see that the regulators have put mechanisms in place to prevent this type of disaster from happening again.
Thanks for listening to this mini-failure episode. For our regular episodes, check out Failurology wherever you get your podcasts. If you want to chat with us, our Twitter handle is @failurology, you can email us at thefailurologypodcast@gmail.com, or you can connect with us on Linked In. there are links to all of these in the show notes. Bye everyone, talk soon!
I hope you liked the mini failure episodes we shared with you today. If you want more, there are others exclusively available on our Patreon page.. For $5/month, less than a pint of beer, you can get access to more of these episodes and you can support our show so we can keep bringing you great content. There is a link to our Patreon page in the show notes for this episode, or you can check out the support page on our website failurology.ca for a link and a list of our current and upcoming bonus episodes.
For photos, sources and an episode summary from this week’s episode head to Failurology.ca. If you’re enjoying what you’re hearing, please rate, review and subscribe to Failurology, so more people can find it. If you want to chat with us, our Twitter handle is @failurology, you can email us thefailurologypodcast@gmail.com, or you can connect with us on Linked In. Check out the show notes for links to all of these. Thanks, everyone for listening. And tune in to the next episode, for another engineering marvel, the CN tower
Bye everyone, talk soon!