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Mound City South Culvert Replacement gets final OK

Published Feb. 7, 2020
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IN THIS PHOTO, Memphis District survey personnel use a drone to photograph the excavation and cofferdam during the 2019 flood. The main levee embankment must be cut to install the new culvert so the cofferdam provides flood protection during the construction process. The riverside slope of the cofferdam was covered with heavy-duty plastic sheeting to protect against erosion and wave wash.

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IN THE PHOTO, (left to right) Jerry Surface, Donald Bond Construction, Sub-Contractor; Lead Field Civil Engineer Jack Ratliff, USACE; Jonathan Hunter, Quality Assurance Rep, USACE; Eric White, Project Manager, USACE; Josh Ozment, Southern Contracting, LLC Project Manager, Prime Contractor; Jacob Allen, Civil Engineer, USACE; Tom Morgan, Civil Engineer, USACE; Daimon McNew, Area Engineer, USACE.

Culverts are essential features that help ensure our levees operate dependably and effectively to safeguard lives and property in areas they protect. It’s also important that we keep these culverts in good repair, or replace them when necessary.

 

To that end, employees from our Caruthersville, Missouri Area Office, the Memphis District office and contractor representatives, recently completed the final inspection of the Mound City South Culvert Replacement Project. The project site is in the confluence area of the Mississippi and Ohio rivers in Mound City, Illinois.

 

“This project consists of replacing an existing 30-inch diameter corrugated metal pipe that has been lined with a 24-inch outside diameter plastic pipe,” Caruthersville Area Engineer Daimon McNew said. “It was fitted with a flap gate with a 48-inch diameter reinforced concrete pipe fitted with both a flap gate and a sluice gate (a manually operated vertical lift gate that is lowered to seal off the culvert). The new culvert was constructed before taking the existing culvert out of service.”

 

The purpose of the gates is to open to allow rainfall to drain out through the culvert into the river while preventing water from the river from flowing backward through the culvert and into the area behind the levee.

 

Technical Lead Ben Tatum said the addition of the flap gate was the result of a proposal from our Value Engineering team.

 

“Our original concept for the culvert had our traditional sluice gate set at the downstream end of the pipe and operated from an elevated platform connected to the levee crown by an elevated walkway,” he said. “However, since this structure is sitting right on top bank of the Ohio River near some busy shipping facilities, we were looking at having to protect the outlet structure with mooring dolphins (big steel piles that act like guard posts or bollards to prevent barge impacts).”

 

Tatum noted that doing so would cost a lot of money, so a change in design was needed.

 

“We changed the design so that the only structure that was directly exposed to the river was a small concrete headwall, recessed down into the slope where it's less likely to get hit,” he explained. “The small headwall was fitted with a flap gate per the sponsor’s request so the culvert will open and shut automatically under most circumstances. However, USACE policy requires sluice gates on mainline Mississippi River structures, since they are much less prone to operation problems than flap gates. So we put the sluice gate in a gatewell that’s built into the river side levee slope, so the earthen embankment can deaden any impact loads from a stray barge.”

 

The VE proposal ended up saving several hundred thousand dollars.

 

“It more than made up for the extra concrete in the gatewell,” Tatum added. “And it resulted in a structure that will be more reliable for years to come.”

 

The Memphis District awarded the approximately $1.4 million contract on Aug. 11, 2017, to Southern Contracting, LLC of Newbern, Tennessee.

 

“This project provides protection to numerous railroads, highways, and airfields connecting the major transportation centers that lie within the protected area along with several major transcontinental communication routes, highly developed agricultural areas, urban areas and many industries which are subject to flooding,” McNew added.