"As I recall those reports, the Sewer Board pulled the original steel, did some work, then drove new steel. "
Yep.
Notice the CoE have yet to utter a peep, officially? They know exactly what happened at every step with the levees that even partially bear their stamp of approval, and they are no neophytes to New Orleans corruption.
I expect they will provide all documentation as requested, and testify when subpoenaed, but they also have to live and work with the criminals that profited from the substandard levee repairs, and probably aren't looking forward to feeding the fishes.
Anyways, it's the agency inspectors who confirm the project is built per plans & specs.