Sandbagging sand boils, harbingers of flooding

 
"We did have a petty big sand boil act up last night, but it's under control today," Chicot County [Arkansa]Judge Mack Ball said Wednesday.

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May 17, 2011, NATCHEZ — More than 2 million cubic feet of water per second are flowing through the Mississippi River at its Natchez pass, and today it is expected to stand at — and then exceed — 61.7 feet.

And Monday, that much water meant the Miss-Lou cities on both sides of the river had to up their flood fights.

In Vidalia, one of the temporary levees made of Hesco Bastion baskets on the riverfront filled with water after a sand boil erupted from the ground Sunday night. The boil originated in the parking area near the front of the convention center.

The boil started to form at 5:30 p.m. Sunday, and inmate crews have worked around the clock to sandbag around the convention center, Vidalia Mayor Hyram Copeland said.

“The Hesco boxes are working fine,” Copeland said. “You are going to have some areas where the river is going to find a way in — in this case we think it was maybe an old drain left over by a construction crew — that will let that water come in and create a vacuum.” The city attempted Monday to plug the boil with several extra-large sandbags flown in by helicopter. Those efforts had to be aborted, however, because the helicopters caused too much turbulence against the Hesco boxes, Copeland said. The mayor said the plugging operation would be attempted again today using a barge loaded with the large sandbags and a track hoe.

As the flood crest has swept inexorably down the Mississippi over the last few weeks, sand boils have erupted in countless locations, sometimes in the middle of towns, other times in fields, and often, ominously, next to a levee threatened by the pressures of the rising waters. I have written a number of posts on the topic of liquefaction as a result of earthquakes, most recently on events in Christchurch, New Zealand, but earthquakes are not the only cause of soil losing its strength and yielding to eruptions of water and sand: the pressures of flood waters create the same effects.

The first stories that I came across of sand boils surfacing in advance of the ongoing devastating floods down the Mississippi were from Cairo, Illinois. Pronounced “Kair-oh” and the original destination for Huck Finn and Tom Sawyer, the town lies at the confluence of the Mississippi and the Ohio Rivers, and has historically experienced severe flooding. The record levels of the 1937 floods that left a million people homeless would be surpassed not long after the sand boils began to appear, the residents were evacuated and the contentious actions of breaching levees and opening flood control gates began. Images from NASA show the normal course of the rivers (left) and the current devastation (right). But look at the swirling patterns of old sand bars left behind by the ever-changing bends in the river channels – it’s a dynamic system.

 
On May 1st, The Missourian reported on a huge sand boil that had appeared in the suburbs of Cairo, and the efforts to control it by sand bags and plastic sheeting:

CAIRO, Ill. -- The mayor of Cairo ordered everyone in the city to leave by midnight on Saturday afternoon, just hours after meeting with the Army Corps of Engineers commander of area flood-control operations.

Maj. Gen. Michael Walsh met with Army Corps of Engineers and city officials to observe a large sand boil caused by the extremely high Mississippi and Ohio rivers. Walsh, the head of the Mississippi River Commission charged with making a decision on breaching the Birds Point levee to relieve pressure at Cairo and other points, described the boil as the largest he had ever seen.

He said that while the boil is stable, it should continue to be monitored.

"There are certainly some concerns in what that's going to do and how this could act as a mechanism that we need to keep good track on," he said.

The sand boil was discovered around 7 p.m. Tuesday in Cairo behind the Napa Auto Parts building. City officials and residents worked about 12 hours through the night to stabilize it.

The Cairo area commander for the Corps of Engineers, Tom Morgan, escorted Walsh through the area of the boil.

"This is the biggest sand boil we have ever laid eyes on," Morgan said.

This operation is shown on the left in the illustration below (from The Missourian’s gallery), and two of the many historic Cairo area sand boils documented by the US Army Corps of Engineers are on the right.

 
The image at the head of this post is from April 27th and the Washington Post; the sand boil erupted near Hickman, Kentucky ominously close to a levee – “The sand bag ring is used to allow the water from the Mississippi River to seep while containing sediment to use pressure to prevent a major break in the levee. (AP Photo/The Paducah Sun, Stephen Lance Dennee).” Hickman is just across the river from Missouri and not far from New Madrid, site of the series of earthquakes in 1812 that not only changed the course of the Mississippi, but caused – yes, liquefaction and sand boils.

Sand boils have appeared through Arkansas, Mississippi, (where the report quoted above on helicopters attempting to stop a sand boil near Natchez comes from) and Louisiana, where, near Vidalia, a sand boil watch has been going on: “More than 25 Louisiana National Guard members from the 769th Engineer Battalion have spent the last nine days walking portions of the 72-miles of levee that protect Concordia Parish residents from the brimming Mississippi River in search of sand boils and seepage.” The article goes on to say

In Concordia Parish, 45 sand boils have been marked and reported to the Army Corps of Engineers, who then make determinations for further action. To date, the Louisiana National Guard has identified approximately 100 sand or pin boils in northeast Louisiana. “Sand boils can possibly weaken the integrity of the levee,” said Vernon Smith, a 35-year veteran at the USACE’s Vidalia office. He said having the Guard out looking in the areas that have historically supported sand boils has eased the burden on his shoulders.

And, last week, The Commercial Appeal of Memphis, Tennessee, carried this photo, as “Deputy Area Commander for the US Army Corps of Engineers, Elizabeth Burks checks on one of several 'sand boils' located on the Ensley Berm (earthen levee), several miles south of the Allen Steam Plant. According to Burks, 'boils are a normal and natural process seen on the dry side of a levee during flooding.' "

Yes, they are normal and natural, but sand boils can be signs of problems with the levees – which is why Elizabeth Burks is engaging in a close encounter with one.

 

[I mentioned the “contentious” issue of managing flooding by intentionally breaching levees and opening flood  control systems. This has indeed been highly controversial – and understandably emotional – but inevitable. For a series of excellent discussions on this difficult issue, misconceptions, and  why the grounds for complaint and litigation may not be as clear-cut as they may seem at first, see Steve Gough’s recent posts, for example here, here, and here. Steve lives north of Cairo and is something of an expert on river systems – he knows of what he speaks. And see also Brian Romans’ post on Clastic Detritus – “Flooding creates floodplains.”

 

 

Comments

[Richard Bready]

Can't resist quoting:

You will not hear it as the sea; even stone
Is not more hushed by gravity...But slow,
As loth to take more tribute--sliding prone
Like one whose eyes were buried long ago
The River, spreading, flows--and spends your dream.
* * *
Damp tonnage and alluvial march of days --
Nights turbid, vascular with silted shale
And roots surrended down of moraine clays;
The Mississippi drinks the farthest dale.
* * *
Tortured with history, its one will - flow!

(from The River, part of The Bridge, by Hart Crane, whose imagination drew freely on geology)

"convulsive shift of sand" (Crane again, Cape Hatteras, in The Bridge)

[Jo Ann Price]

I have a question, hoping some one has an answer for me. The Missouri is flooding, we have a pole barn type of building, our soil is very sandy. Should we try to pump the water away from the building? Will the quicksand that forms help or hurt the structure?

[Sandglass]

I wish that I was an engineering geologist and was equipped to answer your question!

Is there anyone reading this who can????

I will respond separately by e-mail and copy it to one engineering geologist whom I know.