An Earthquake Is 'The Most Sinister Threat' To Metro East Levees During Flooding
With the Mississippi River at its second-highest level in history, Metro East Sanitary District Executive Director Steve Adler has three worries.
The first is people. The second is more rain. The third thing is the most sinister and potentially catastrophic, he said. It’s an earthquake.
Adler tells people who live behind the levees that when the river is above 30 feet, if they feel the ground shake, leave.
“Grab the kids. Grab the dog. Get in your car and drive up to the bluffs,” Adler said.
The levees were constructed of topsoil over sand, Adler said. In the event of an earthquake, the shifting of tectonic plates could cause the levees, already under pressure from the high river water, to shift, allowing water to pour in.
“It’s a very rare thing, but (it’s) the black swan events in human history nobody expected,” Adler said.
Robert Herrmann, a seismologist at St. Louis University’s Earthquake Center, agreed. An earthquake would have to be large to cause the levees to fail in St. Louis, Herrmann said, adding it would happen “almost never.”
He said there is a slightly higher threat to areas down river.
But a catastrophic levee breach puts lives in jeopardy, Adler said. There are 130,000 people who live behind the Metro East Sanitary District’s levees which stretch from Granite City to Cahokia.
Madison County residents who lived behind the levees can sign up for the county’s emergency notification system, CodeRED. The system will give them an alert if there is a levee breach to allow them time to reach higher ground.
And with rivers much over flood stage, Adler encouraged people to stay off the levees with their vehicles, including four-wheel drive trucks, motorcycles and all-terrain vehicles.
“It doesn’t take a whole lot of damage to create a failure,” Adler said.
The Illinois National Guard is patrolling the nearly 38 miles of levee that extends from west of Granite City to south of Cahokia.
Adler noted the 1993 case of James Scott, who intentionally breached a levy near Quincy. Scott was tried under a Missouri law that made it a crime to cause a catastrophe. Witnesses testified that Scott breached the levee to strand his wife on the other side so he could fish and party. He is currently serving life in prison.
“People just need to stay away right now. It’s dangerous,” Adler said.
The river levels have been high since November, but so far, Adler said, the levees aren’t showing signs of saturation.
“They are short-term fixes,” Adler said.
Every drop of rain that falls behind the levee has to be pumped out to the river, or more flooding could occur. Last month, the St. Louis area had seven inches of rain — three more than monthly average, according to the National Weather Service.
The weather may not cooperate.
Thunderstorms are forecast for the weekend.
“When things are this bad, it doesn’t take much to make it worse,” Charles Graves, a meteorologist at St. Louis University.
The levees also weren’t designed to hold so much water for so long, Adler said.
On Friday, the river was at 45 feet, 15 feet above flood stage. In 1993, the river reached the historic one-time level of 49.6 feet.
The levees are around 52 feet with two feet of freeboard. Freeboard is the vertical distance between the crest of the embankment and the water surface.
“I think that, going forward, we need to take a look at the height of our levees to see whether or not they are sufficient for the future,” Adler said.
Four of the top 10 floods in the area have happened since 2010. Development and climate change are causing the Mississippi River levels to rise, Adler said.
The U.S. Army Corps of Engineers said the chance of an event that causes an overtopping of the levees is once every 3,300 years, Adler said.
“I tend to believe them, but I also believe we should trust, but verify, that those numbers are still relevant today,” Adler said.
Adler was forced to close floodgates last week, shutting off vehicle traffic to the river. A million dollars worth of coal came through one gate every day, Adler said, headed to the steel plant in Granite City.
“We kept them open as long as we could, but the water got too high,” Adler said.
Projections are that the water won’t recede anytime soon. For now, Adler said the levees and his crew are holding up.
“We are going to keep going, just as we have for decades,” he said. “The names and faces change, but we just keep holding back this river.”
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