Posted on October 11, 2022
By Judith Powers
The Corps dustpan Dredge Hurley has removed shoaling from the Mississippi River that had shut down navigation in the river. Scores of towboats and barges moving in both directions had been halted and were moored along the riverbanks.
On Friday, September 30, the U.S. Coast Guard closed the Lower Mississippi River to traffic at Stack Island 200 miles (322 km) north of New Orleans from mile marker 478 to 482(769 km to 775.7 km) due to a barge and tow grounding and other shoaling in the area. There had been at least eight groundings in that area in the previous week “despite low-water restrictions on barge loads,” according to an Associated Press report.
The Mississippi River Channel is maintained at 300 feet (91.4 meters) wide and nine feet (2.7 meters) deep.
A further grounding at a shoal below Memphis at RM 681(1096 km) caused the Coast Guard to close the river there at approximately 6:00 pm local on October 3. At that time there was a backup of 24 vessels and 1,734 barges for both directions at Memphis, according to a Coast Guard source.
A shipping company manager told DredgeWire that on October 7, there were 185 towboats and 2,900 barges combined at both Stack Island and Memphis. (The Coast Guard reported 110 vessels and2,081 barges.)
“This represents 15 percent of the overall fleet capacity on the inland waterways,” he said. Regarding his own company’s vessels, he said that 1/3 of their towboat horsepower and 15 percent of their barge fleet “is trapped there.”
Among the stalled vessels was a cruise ship, the Viking Mississippi, which had been heading from New Orleans to St. Paul, with stops along the way. On Friday, Oct. 7, Susan Taylor, Port Director of the Port of St. Louis, reported that the ship’s arrival at St. Louis on Oct. 8 had been cancelled. The Viking company had cancelled the trip at Vicksburg and issued refunds to the 350 passengers.
The shoaling at Stack Island was cleared by mid-day Friday, Nov. 7, and the Hurley began the journey upriver to the shoal at Memphis – a distance of 200 river miles (322 km), with an estimated arrival date of Tuesday, Oct. 11.
The Hurley is a 353-feet-long (107.5 m), 58.5-foot-wide (17.8m)self-propelled dustpan dredge, with a seven-foot (2.13 m) draft designed to remove sand in a wide swath using a wide bow-mounted dustpan head. Propulsion is by diesel engines totaling 5,700 hp. High-velocity water jets liquify the bottom material, which is drawn into pumps powered by two 1,500-hp motors and discharged into the current downstream through a maximum 1,000-foot (304.8m) 32-inch (81.2 cm) pipeline. This configuration allows for the most economical removal of large amounts of material. With a capacity of 5,000 cubic yards (3822.7 cubic meters) per hour, the dustpan dredge can quickly clear shoals in a wide swath, to a maximum depth of 75 feet (22.8 meters), then easily move to the next location. The Hurley belongs to the USACE Memphis District, Hensley Engineer Yard.
Restoration of normal traffic the length of the river will involve reconfiguring up- and down-bound tows at St. Louis. Tows traversing the Upper Mississippi, which is divided into pools by the lock and dam system, are limited to 15 barges under current conditions. Tows on the Lower Mississippi can run up to 28 barges from St. Louis to New Orleans because of the absence of locks and dams.
At St. Louis, tows are reconfigured at shipyards and fleeting areas. Traffic going upstream into the lock and dam system must be reduced in size, and tows coming downstream can take on more barges for the Lower Mississippi run. Shipyards and fleeting areas perform this function. When the freed-up tows converge on St. Louis, they could cause a bottleneck for reconfiguration.
Though there is potential for low water issues in the Upper Mississippi, this has been mitigated by the lock and dam system. Dan Cottrell of the St. Paul Engineer District at Fountain City, Wisconsin told DredgeWire that at the moment, navigation on the Upper Mississippi is not affected because the dams are able to support the water depths, having no added purpose such as flood control or hydropower.
The system was built in the 1930s, and includes 29 lock and dams on the Mississippi, and eight lock and dams on the Illinois River, which allows transit between the Mississippi River and the Great Lakes.
This article has been corrected. The maximum number of barges in Upper Mississippi River tows is 15, not 20 to 25 as previously reported.
