Marseilles, Ill. (April 25) – The U.S. Army Corps of Engineers, as part of the Unified Command, completed its initial assessment of damages to Marseilles Lock and Dam on the Illinois Waterway Thursday after seven barges allided into the dam on April 18.
The lock remains closed as the Corps continues assessing damages, and barge removal operations continue.
The damage caused by the allision has compromised the Corps’ ability to operate the dam in accordance with to its operations manual.
Although damage to the dam will require significant repairs, the Corps has determined the dam is safe and currently poses no risk to citizens in the area. However, in its current condition and with flood waters receding, the navigation pool will be lost to some degree for an undetermined period of time. The Corps is working with the U.S. Coast Guard to identify potential impacts.
Marseilles Lock and Dam is operated and maintained by the Rock Island District of the U.S. Army Corps of Engineers. Marseilles Dam incorporates eight movable Tainter gates that raise and lower to maintain a pool with a minimum nine-foot navigation channel during changing river conditions. The overtopped earthen dike at Marseilles, Ill., is a component of the Marseilles Lock and Dam project. The dike was authorized and constructed to contain the navigation pool resulting from the dam’s construction. The dike was not constructed or designed to mitigate risk from flood events.
Following the accident, high water from record flooding made the dam inaccessible so the gates could not be inspected until April 21 when water receded. A Corps of Engineers’ initial inspection determined that five of the eight dam gates sustained significant damage due to the allision. That damage included denting and bending of steel members in addition to concrete abrasion damage. Additional structural inspections and scour surveys will be completed after the barges are removed.
The initial assessment also revealed that two of the gates (Gates 2 and 3) experienced a tearing of the upstream steel face resulting in 15 to 20-foot long holes in the gates. Scour and erosion damage also occurred to the earthen dike due to overtopping.
The Corps has concluded that the most critical damage caused by the alision is to the gate trunnions, which are basically hinges. The trunnions on Gates 2 and 3 have been severely damaged with the trunnion anchor blocks broken off and displaced downstream into the river. This trunnion damage has resulted in Gates 2 and 3 becoming inoperable. Gate 2 has also been displaced downstream and is wedged within the dam gate piers. Measures are being identified to stop water flow through Gates 2 and 3 until these gates can be repaired.
“Corps of Engineers dam safety officials and structural engineers are working to determine the extent of the damage caused by the barge impacts and the high river flows,” said Tom Heinold, deputy chief of the Operations Division for the Rock Island District. “As soon as conditions permit, the Corps will perform engineering analyses for use in developing repair and recovery plans, ensuring that the dam can be returned to an operational status as soon as possible.”
According to Heinold, a combination of temporary measures and follow-on permanent repairs will ensure that the Marseilles navigation pool is reestablished as soon as possible.
In response to the accident, a Unified Command Center was formed in order to ensure a coordinated, joint effort. The Rock Island District of the Corps of Engineers is part of a Unified Command Center which includes representatives from the U.S. Coast Guard and industry.
For information about the incident, contact the Unified Command at: 216-389-0420
For information about the Marseilles Dam, contact: U.S. Army Corps of Engineers, Rock Island District
Ron Fournier, (309) 794-5274, Ronald.F.Fournier@usace.army.mil
Allen Marshall, (309) 794-5204, Allen.A.Marshall@usace.army.mil