July 26 - A tow moving barges on the Illinois River lost control in the strong river currents April 18 and seven of the fourteen barges that broke free ended up against the Marseilles Dam.
The Dale A. Heller was approaching the entrance to the Marseilles Lock canal when the current pushed the tow toward the dam. Of the seven barges that impacted the dam three remained floating while the remaining four sunk.
A Unified Command consisting of the U.S. Coast Guard, the barge industry and the Corps of Engineers was quickly established to ensure a coordinated, joint effort in response to the April 18 incident. The Unified Command’s main priority was ensuring the safety of the public in the area during removal of the barges at the dam.
Record high river levels delayed the Corps’ inspection of the dam until April 21.
The initial inspection determined that five of the eight dam gates sustained significant damage during the collision. That damage included the bending of the steel skin plates and structural members in addition to concrete abrasion damage.
It 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.
The most critical damage was to the gate trunnions, which are hinges that anchor the gate to the dam. The trunnions between Gates 2 and 3 were severely damaged and the trunnion anchor beam was completely broken off causing the gates to be inoperable. Gate 2 was also displaced downstream and was wedged within the dam gate piers.
In addition to the damage at the dam, an adjacent earthen dike upstream of the dam, constructed in the 1930s as part of the Marseilles Lock and Dam project, had scour and erosion damage following its overtopping. That overtopping caused several hundred homes and a school in Marseilles to sustain significant flood damage.
“Anytime you have that amount of water overtopping an earthen dike or embankment, the chance for scouring is significant,” said Andrew Barnes, Project Manager for the Marseilles Dam Emergency Response. “The earth dike was overtopped by two feet or more in some places. Our initial assessment discovered many issues that needed our attention.”
One issue that came to bear was easement encroachments. Many of the residents who experienced flooding behind the earthen dike had federal easements on their land. It became imperative that the Rock Island District reach out and communicate to the residents regarding the easements.
“There were a lot of angry residents which is very understandable,” said Ron Silver, the District’s realty specialist assigned to the Marseilles Dam emergency. “We endeavored to contact as many residents as possible – in person. They needed to understand what challenges our federal easements may present to their property.”
According to Silver, some residents had built structures on the easements which may have to be removed to facilitate repairs to the earthen dike and allow District engineers to fortify the dike and bring it back to pre-flood event conditions.
The Corps also mobilized Hydrographic Survey crews and their equipment to complete a thorough underwater analysis of the damages to the dam and to gather information on the potential scouring of the riverbed adjacent to the dam and sunken barges.
“There was concern that the barges caused a new flow regime that could exacerbate scour of the bedrock,” said Matt Stewart, the District’s dam safety program manager. “The surveys showed that there was no significant scour present – which is what we were concerned about. Public safety was our number one concern and this survey helped alleviate some of our concerns regarding the safety of the dam.”
With the dam deemed structurally sound, the Corps looked to the next issue of not being able to operate two of the gates, which meant the ability to maintain the 9-foot navigation pool came into question. This would not only affect navigation traffic but also the many recreational boaters, marinas and other users. There is also a nuclear generating station that draws cooling water from the Marseilles pool.
The Corps quickly devised a plan to construct a temporary rock dike which began April 30. The dike, designed to block uncontrolled water flow through the inoperable dam gates, helped to maintain the navigation pool upstream of the Marseilles Lock and Dam.
“The rock dike allowed for the placement of temporary bulkheads over Gates 2 and 3 at the end of June,” said Stewart.
These bulkheads block the flow of water through the bays of the inoperable gates.
To complete the dike, the Marseilles pool was drawn down four feet beginning May 11. The Corps worked closely with the U.S. Coast Guard and the barge industry, as well as local boaters and marinas to facilitate the necessary preparations prior to and during the drawdown.
"Lowering the water levels reduced the volume of water flowing through the broken gates," said Mike Cox, chief of Operations Division. "The reduction resulted in less erosive forces being placed on the rock dike and facilitated the safe completion of the dike."
According to Cox, the decision to draw down the pool was extensively evaluated and was one of many alternatives considered to reduce flows.
The dike, completed May 13, was constructed using approximately 42,000 tons of rock and stretched more than 300 feet.
“It was very impressive to me that our operations crews were able to complete the dike so quickly,” Barnes said. “They worked 24 hours a day knowing that it was critical for us to get the dike in place as quickly as possible.”
The navigation pool was fully restored May 15 allowing navigation traffic to resume.
More excitement was in store two weeks later when the precipitation forecast indicated a high risk of river stages overtopping the earthen dike and the recently completed rock dike around June 2. The contractor for the earth dike initial repairs was mobilized and between May 29 and June 1 the earth dike was raised approximately four feet to counter this risk. The Corps’ Operations crews raised the rock dike a similar amount during the same time frame.
Alongside of the Corps constructing the rock dike, fabricating bulkheads and performing hydrographic surveys, the Unified Command was coordinating salvage operations of the barges – which also included District employees and equipment.
The first barge was removed April 23 followed by three other barges between then and April 30 when operations were temporarily ceased during dike construction.
To successfully remove the barges, most of them needed to be emptied which required some heavy lift cranes and other specialized equipment. The District’s heavy lift crane Hercules and the Manitowoc 777 were used to assist in the lightering of several barges in order for them to be removed safely.
“This required close coordination with all parties involved. It was a challenging process to remove the barges and to do it safely,” said Cox.
Salvage operations to remove the remaining two sunken barges resumed with the completion of the rock dike. Their removal required the use of specialized equipment and was a very labor intensive process. Before lifting and removing the barges, their cargo was removed. The first one was carrying large heavy steel plates; some as large as 40 feet in length, 8 feet wide and weighing up to 7,000 pounds each.
The final barge was safely removed June 17 marking the end to salvage operations and the Unified Command.
Upon removal of the final barge a comprehensive hydrographic survey was conducted upstream of the dam. To everyone’s relief no significant scour was found said Stewart.
“Now that the salvage operations are complete we can get a closer and more complete look at the damages,” said Barnes.
The District’s Project Delivery Team continues to work on the temporary and permanent repairs of the Marseilles Dam. A temporary repair to the damaged trunnion anchor beam supporting Gates 2 and 3 will be attempted while the existing trunnion anchorages will be evaluated by a specialty contractor. A third bulkhead will be used to allow full inspection and assessment of Gates 4-6 throughout the summer. The full scope of required repairs is expected to be determined by mid-September.
“The response by the entire District to this incident has been an incredible team effort. All of the people working on this, whether they are in Operations, Engineering & Construction, Contracting, Safety – have displayed a remarkable willingness to do whatever it took to complete the job. I think the District should be proud of the effort and the results,” said Barnes.