|
In October 2003, construction began to raise the Mississippi River levee in Issaquena County, Miss., by about 5 ft.
Barring any weather delays, the $28.3 million, 8.84-mi. project, which is halfway between Greenville and Vicksberg, Miss., will be completed in November 2006, said John Thomas Kerr, a construction representative for the U.S. Army Corps of Engineers.
The project calls for dredging the Mississippi River for sand, which is being used along with berm material to raise the levee to 37 ft. high. Adding the extra feet to the levee will require 1.97 million cu. yds. of berm and sand, Kerr said.
The prime contractor, Weeks Marine Inc. of Cranford, N.J., is dredging the Mississippi and Chancellor and Son Inc. of Cordova, Tenn., is raising the levee.
Scheduling the work for the two companies is one of the challenges the project has faced, said Sam Horton, the Greenwood area engineer for the Corps of Engineers.
"We have to kind of match their schedules to determine which activities are the most critical," Horton said.
Tom Hurley, Chancellor and Son's project manager, said his crew first had to clear the areas to build a 20-ft. retaining dyke about 400 ft. from the levee.
Hurley used a variety of earthmoving equipment to move the berm material to the site. It took about two years to construct the retaining dyke and nearly 800,000 cu. yds. of berm, Kerr said.
With the retaining wall in place, Weeks Marine is using a 30-in. hydraulic dredge to pump sand and water over the top of the levee.
"It kind of makes for a catfish pond there," Kerr said. "And of course, we're pumping the water back to the river . . . leaving the sand between this dyke and levee."
Using the sand for the levee's fill minimizes the amount of dirt needed from the riverside areas, Hurley said.
"That's why (the Corps of Engineers) is going to the added expense of dredging the material, to make it more environmentally pleasing," he said.
Weeks Marine retrieved the sand from a series of stone dykes in the Mississippi River.
"The sand gets trapped between those dykes," Hurley said.
While the sand is being dredged, Chancellor and Son uses off-road highway trucks, off- road dump trucks and articulated trucks to haul dirt from the borrow areas on the riverside to build up the levee, Hurley said.
But because the dirt "was extremely wet" it had to dry before the next layer was placed to avoid sliding.
"If you keep piling slop upon slop, you know what happens: it runs," Kerr said. "So that's the reason for controlling the moisture."
Hurley said each layer of berm is about a foot, but when it is packed it falls to 8 in.
"As you raise the top, you've got to widen the levee to make up for it," Hurley said. "So we're coming up 30 ft. off of the base."
To avoid placing wet dirt on the base of the levee, Chancellor and Son let the dirt dry for two or three days before another load was placed on top of it, Hurley added.
The challenge has been working around nature's schedule, Hurley said.
"You have a short working season because of the Mississippi River flooding," he said. "The flood waters don't recede until June or July and the water gets too bad to work by November."
That gives Chancellor and Son only four or five months to work on the project. And by not working on the project for months at a time, it makes it difficult maintaining a work force, Hurley said. Still, when the sun's shining, the crew of about 40 to 50 employees is working seven days a week.
After the dredge is filled with sand, Chancellor and Son is taking scrapers and degrading the retaining dyke and capping the sand with dirt. Bermuda grass is then planted, which will help the dirt remain in place.
While the purpose of the project is to raise the levee, Kerr said he didn't know if the higher levee will keep the river from flooding.
"That's the $100 question," he said. "You don't know every winter - and especially every spring - what Mother Nature is going to throw at you. But the higher protection you have, the better off you are."
Click here for more Features >>
|
print this page
e-mail this page
