Tuesday, June 24, 2014

Marseilles Dam Accident

US Government
I was researching the Marseilles Hydro Plant, and I discovered that the NTSB released their report (new URL) today. When I first read about the barge allision with the Marseilles Dam last April, 2013, I wondered why the captain would try to navigate into the canal during river flood conditions. It turns out, he got in trouble because he was conservative. He held up 0.75 miles upstream on April 17, 2013, when the gates were open to 31% of the full capacity to wait for better conditions. The problem was that the conditions got worse. By the next afternoon the gates were open to 92% of capacity. The captain wanted to tie up, but another tow got the only mooring in the area. A conference call was held with the River Industry Action Committee, Illinois River Carriers Association, the Coast Guard, the Corps, and others to determine how to help the 14-barge tow. It was decided that the towboat for the other tow and two Coast Guard towboats would help shove the tow into the safety of the navigation canal. The plan included temporarily reducing the flow rate through the dam during the maneuver. However, when they reduced the flow, they increased the flood threat of the town Marseilles. So the flow was increased and the maneuver failed. Seven of the barges broke away from the tow and crashed into the dam.

The damages were almost $4 million for the barges and cargo, $10 million for temporary repairs, and $35 or $50 million (I've seen both numbers) for permanent repairs. And shipping was sometimes shutdown on the river after the accident to lower the pool to reduce the pressure on the broken gates and the cofferdam that was being built to help with the repairs.

The Corps had created a slide presentation that describes the incident, both the barge allision and the earthen dike damage, and the temporary repairs.

Update: Hercules, a 60-foot barge mounted crane, helped remove the barges.

Massman's project web page contains eight photos with the comment:
The Corps of Engineers awarded Massman Construction Co. a contract to perform repairs to the Marseilles Dam in Marseilles, Illinois. The dam was damaged from several runaway barges that collided with the dam as a result of strong river currents from heavy rainfall. Massman completely replaced three tainter gates and repaired two others.
Erection of the shoring system to support Gates 2 and 3 during the replacement of the trunnion girder began once the riprap was removed. All material had to be picked from the barge located upstream of the dam using the Manitowoc 4100 and moved over the dam to be set in place on the downstream side. Crew accessed the shoring installation from 2 Snorkel man-lifts located downstream on the existing rock dike. The shoring system, consisting of six (three per gate) HP 12 x 53 shoring piles tied back to the concrete piers, was installed and the gates were lowered onto the shoring. Two platforms were then erected off the shoring piles on either side of Pier 2 and the drill platform was erected on the downstream face of Pier 2.
The crew successfully removed the trunnion pins at Pier 2 from Gates 2 and 3 to release all load from the temporary trunnion girder. Once the pins were removed, the existing temporary trunnion girder was removed from the downstream side of Pier 2. This cleared the area for core drilling of 8 each 3 inch diameter holes into Pier 2. These holes will then have eight 1.75 inch diameter threaded bars installed for the anchorage of the new trunnion girder. Gate 3 repair work started following the installation of the new trunnion girder.
Massman removed the riprap from the downstream side of Gate 2 and Gate 3 to provide a clean surface for installation of the shoring. 








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