- Associated Press - Thursday, August 20, 2015

AVON, Miss. (AP) - Four years after the 2011 flood, the 212-mile long levee is still trying to recover. But not for much longer as more than 40 relief wells are being installed in Avon and a handful more are being placed in other Delta towns, thanks to federal money given to the Mississippi River and Tributaries Project.

Congress, after the 2011 flood, appropriated $802 million to the Mississippi River and Tributaries Project, which runs from Cairo, Illinois, to the Gulf of Mexico. The money, Congress said, was to go toward repairing levees that were damaged during that year’s high water levels.

One way to fix some of the problems is by installing relief wells. Mississippi Levee Board’s chief engineer Peter Nimrod said a relief well is essentially a water well without a pump or motor.

Under seepage travels under the levee, intersects the well filter sand, which blocks any solid material, and then enters the well through the well screen and the pressure pushes the seep water out the top of the relief well.

Nimrod said during the flood - and since - temporary measures were put into place, including placing sandbag rings and barrels over sand boils and blocking off ditches to stop the flow of dirt.

Once federal funds were approved, the U.S. Army Corps of Engineers surveyed the problem areas and used drill rigs to complete soil borings to test and map out what the soils were like under the surface. What they found were 12 major problem areas along the levee system, including in Avon and Greenville.

A $3 million contract was awarded to Avon, which includes five different sites.

Nimrod said the relief well installation, which is being completed by Vicksburg-based Riverside Construction, includes installing 43 relief wells in Avon; six relief wells in Greenville; 12 relief wells in Leota; 21 relief wells in Lake Jackson; and 16 wells in Loman.

“These guys are really good at putting relief wells in. They know what they’re doing; they do things really fast,” Nimrod said.

Nimrod said sand boils, which move material from underneath the levee, had been steadily appearing in Avon.

“The problem with sand boils is it’s moving material from underneath the levee. If you keep letting it go on and on, eventually it’ll undermine your levee, and eventually your levee will fail,” he said.

“Every day, we’ve had to watch it to make sure it wasn’t getting any worse and make sure you didn’t have to adjust something to make sure it wasn’t going to get in a worse situation. That was one of our headaches.”

Nimrod said the Corps designed a permanent solution so that sand boils won’t occur any longer in these locations: relief wells.

“Relief wells are great because you can have them spaced out however you need them, how deep you need them,” he said.

“They will relieve the pressure by allowing the seep water to escape in a controlled manner without allowing any movement of material; so there’s no sand boil that will be created. There’s no cavity or hole being formed underneath the levee system.”

Nimrod said a 110 foot-wide landside seepage berm has also been built in Avon as well as the 43 relief wells, which is currently being completed.


Information from: Delta Democrat-Times, https://www.ddtonline.com

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