Submerged Dikes to Control Sedimentation

Category:

Coastal/Hydraulic Systems

Dredged Material Disposal

Operating Procedures

Description:

Submerged dikes constructed of sand-filled geofabric containers used to manipulate river flow

and control sedimentation.

The U.S. Army Corps of Engineers, New Orleans District designed and constructed the Red Eye

Crossing Soft Dikes Demonstration Project for $7.1 million in 1994. The Red Eye Crossing is

about 2 miles long, with the channel crossing from the east bank to the west bank. Crossings

create water conditions conducive to shoaling. The Red Eye is particularly troublesome because

the channel is relatively wide at that point, about 3,700 ft. This forces the Corps of Engineers to

bring in dredges to maintain the 45-ft channel to Baton Rouge. Each year, the Corps brings in

two dustpan dredges, the government dredge Jadwin and a private dredge, to remove sediment

deposited in the high-water season. Sometimes, hopper dredges must be called in as

reinforcements. The intent of the Red Eye soft dikes is to provide passive dredging whereby the

Mississippi can dredge itself. Fewer cubic yards must be dredged, saving the government

millions of dollars and avoiding the consumption of thousands of gallons of diesel fuel.

Six submerged dikes were constructed using geofabric containers, both larger geocontainers

(200-300 yd3) and smaller geobags (3 yd3), filled with coarse river sand from a nearby shoal.

The containers were filled and sewed shut in a split hull barge. Once the bag was closed, the

bottom of the barge opened to drop it into place in a dike at the crossing. The contractor was

Luhr Bros., Inc., based in Columbia, Illinois.

The six soft dikes are perpendicular to the river flow, extending along the east bank for just under

1 miles. The dikes are progressively longer going downstream, from 680 ft to 1,750 ft. The

intent of the dikes was to constrict the Mississippi's flow, concentrating it in a narrower channel

to increase flow velocities and decrease sedimentation. This constricted Red Eye River to about

2,000 ft, the same as the width of the non-dredging crossings the Corps was trying to mimic. The

Red Eye dikes are similar to hundreds of rock dikes that have been used successfully for many

years on the river above Baton Rouge. As they are soft, they are safer and unobtrusive. The soft

dikes lie lower than the nearby sandbar that was used to fill the bags.

Navigation safety has been a prime concern with the soft dikes. The first 4 years have seen no

reported incidents attributable to the project.

The Red Eye project will have paid for itself by the end of 1998. The Corps is preparing to move

on to other river crossings below Baton Rouge, with the Medora Crossing next, located 12 miles

downriver from Red Eye. The Medora dikes, whose construction is planned for fiscal year 1999,

will have three dikes, as opposed to the six at Red Eye.

Reviewer:

J. Lally

Company / Organization(s):

(Continued)

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Chapter 5 Other Technologies Reviewed