The U.S. Army Corps of Engineers has a long history of building projects to last. But 95 years is asking a lot from any structure. So when it became necessary to replace some enormous steel gates that are part of an Inner Harbor Navigation Canal (IHNC) lock in the New Orleans District, the challenge was monumental.
But Memphis District structural engineer Marneshia Richard proved she was up to the task when she was assigned a central role in the project.
“I was the designer of the pickup configuration,” Richard said. “My job was to come up with a way to safely remove the old gates and not damage them in the process.”
Richard said the original designers made the gates so they could be removed by “floating” them out using buoyancy tanks. Because of the age and condition of the gates this method was no longer possible.
Built in 1921, the IHNC joins Lake Pontchartrain in the north with the Mississippi River to the south. It allows large commercial shipping to safely pass through a highly urbanized area within the New Orleans city limits.
Although each of the two gates weighed roughly 250 tons, they were made of 1921-vintage bridge steel and joined together entirely with rivets.
“The old gates were not as strong as the new gates and we had to figure out a way not to overstress them as we lifted them up and laid them horizontally on their sides,” Richard said. Engineers wanted to ensure they had the option of reinstalling the old gates until they were sure the new gates fit correctly and were operational.
Richard said she and other engineers from the New Orleans District considered a number of different solutions, then the New Orleans group suggested installing pins and pad eyes to lift the gates using a heavy duty floating crane.
“I liked the idea New Orleans came up with,” Richard said. “My job was to do the structural analysis, check the possible stresses and ensure they could remove the old gates and not damage them in the process.”
Here’s how it all worked.
Workers drilled two holes through the top of the gate then installed pins through the holes. Each pin was nine inches in diameter and four feet six inches long. Once the pins were in place, collars were welded around the pins to help stabilize them. The final step was to install pad eyes so a crane could lift each gate and gently lay it down on a waiting platform barge.
All this came together on Aug. 29, 2016. The Rock Island District’s Quad Cities crane took care of the heavy lifting and their M/V Bettendorf helped keep everything steady during the delicate maneuver.
Although other duties prevented Richard from being present for the actual removal operation, she says she still took a lot of satisfaction in the assignment.
“I enjoyed the responsibility,” she said. “It was a unique project, had to be done in a short time frame and was sensitive due to the potential safety concerns. We didn’t want anything to fail or anyone to get hurt.”
Richard first began working for USACE almost seven years ago in the Vicksburg District. She transferred to the Memphis District two years ago and has worked on a number of important projects.