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 accident 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.

No comments:

Post a Comment