It was mostly geotech failures related to the organic material mentioned above, combined with a patchwork system at that point in time. The post-Katrina improv

It was mostly geotech failures related to the organic material mentioned above, combined with a patchwork system at that point in time. The post-Katrina improvements have combined the patchwork systems into one. The improvements should have been made long before Katrina, but the corps of engineers stalled most attempts, and Congress refused to let the corps do anything without direct Congressional funding, which never came. Until Katrina.