In a demonstration of collaboration and innovation, the U.S. Army Engineer Research and Development Center deployed an experimental asset and team of experts to the Missouri River in the Kansas City District, U.S. Army Corps of Engineers, to assist in dredging shallow areas called shoals in the navigation river channel.
Missouri River Basin partners include major agricultural producers of soybeans, corn and other crops and often bring their crops down the Missouri River from Iowa, Nebraska, Kansas and Missouri, and then on to other shipping locations on the Mississippi River. Commercial shippers often bring fertilizer, coal, gravel and other trade items to the upriver locations so that both sides of the journey provide production.
Flood damage from the catastrophic flooding of 2019 and from an additional two years of high water in the basin, has damaged many of the navigation support structures, wings and dikes, that direct the current of the river to self-scour the navigation channel. When the structures are damaged, material falls out of the slower moving parts of the river and can cause sediment or sandy material to settle on the river bottom, making the depth of the navigation channel too shallow for tugboats and the barges they push to pass.
Thad Pratt, Military Technical Director for ERDC’s Coastal & Hydraulic Engineering, with the Corps for 32 years, working in and from Vicksburg, Miss., provided oversight and leadership for the group that traveled by road, using a lowboy trailer to haul the hydrodynamic dredge to central Missouri from the ERDC headquarters in Vicksburg. As the lead for a team of five experts, the team spent about two weeks reducing shoaling, usually sand and gravel – from the 300-foot wide, nine-feet deep navigation channel that the Kansas City District has the charge to keep passable for navigation.
After Pratt learned the Kansas City District was having issues with shoaling in the Missouri River affecting navigation from the Headquarter River Engineering contacts - he had experience from working the river performing studies over the years - he realized the ERDC-developed military dredging system’s track-hoe mounted version of a hydrodynamic dredge could offer a solution.
He called the Kansas City District River Engineering team and received enthusiastic interest. The Kansas City District team told him they could provide a barge and other materials needed to deploy the system and had several areas of concern on the river that needed spot dredging to reopen to commercial traffic. The Vicksburg District kicked in a lowboy trailer to take the heavy equipment to Missouri. Pratt said his team had not used the pump that way – on an inland waterway - but were excited to try it.
Got it set up. The Kansas City crew had a lot of experience and two groups melded their thought processes together and went to work. An underwater visualization system proved valuable for the track hoe operator. By using hydrographic surveys in the background of the underwater imagery, the operator could directly remove sediment from the shallow points. The team on the barge would float right on top of the shoal and then the track hoe operator would go to work with the pump attachment mounted on the end to the track hoe.
But, instead of sucking the sediment and water mixture, called slurry, up into the pump and then through a discharge pipeline out of the channel, this attachment had been modified to work in a different way. This “hydrodynamic dredge head” jetted the slurry back down into the channel bottom sediment to fluidize it up into the water column where the river current could carry it downstream out of the shoal area into deeper water. This hydrodynamic dredging method let the crew move more sediment out of the channel than they would have in the conventional way.
Over a couple of days, the team was able to clear the channel at river mile 283. They traveled on to river mile 92 and then one of the bearings of the pump locked up and they were able to rebuild the pump system after getting replacement parts from Ames, Iowa.
The river had gotten a half-foot of additional water - from Kansas City District reservoir releases and some rain – and the need for the dredge as Thanksgiving approached lessened to the degree that the personnel redeployed to Vicksburg. The Kansas City District shipped the equipment back over the next couple of weeks. The ERDC team learned important lessons about the equipment and how to use it effectively on inland waterways.
he Vicksburg District has now bought a similar system to use in a local river system. They bought the track-hoe version which is better for their needs in targeting localized specific build up. It works more efficiently to take the upper surface off a shoal and keep the debris moving or to clear up the entrance to a port. The Corps can mobilize this system for $3,000 to $4000 per day versus $50K per day for a larger traditional commercial dredge.
he track-hoe version is versatile at working in tight spaces including locks and piers. The tracked version was built to facilitate landing on a beach for the Navy by ERDC – logistics over the shore It can come from the shore or from the boat to clear an obstacle. But the Navy, like most combat organizations, does not want to have to carry larger equipment with them if they don’t need it – so at other times, the version that attached to a track-hoe proves more versatile.
Either system will fill HESCOs – large wire-reinforced barriers easy to transport when empty - with wet sand very quickly – making it very cost effective. They work well cleaning off boat ramps or to dredge material that can quickly and efficiently be directed onto the shore or into deeper water.
Many Corps districts are looking to use their own maintenance crews on smaller projects and take care of the taxpayers’ money by spending less.
“Our system is a prototype built for the military – we’re trying to find all the best uses for the equipment. The Civil Works community does have lots of projects that may need this as a potential solution,” said Pratt.
One example will be use on Olmsted Dam – Ohio River, to remove sediment from the hinge point of gates on the dam. Divers can remove debris and sediment there but that is risky and expensive. The ERDC team is adding a function to the onsite track-hoe to modify the pump to use as a high-pressure washer and can do it from the surface – no diving. This is clearly quicker and potentially much less expensive. ERDC is fabricating them an attachment to use as a high-pressure head to try this out. It will be tested to ensure it will not damage the structure of the dam.
The Kansas City District and our partners who work on and around the Missouri River benefited greatly from ERDC delivering this innovative solution and sending the team with it to affect positive change on the usability and safety for operating on the river.