Troubles with the trench again
During the Corps' gate closure drill on May 15th, 2007 which took place at all three floodgate sites, apparently they had some trouble closing the gates at 17th Street. Why? There was construction debris in the trenches into which the gates seat. Apparently, at least one and possibly more gates stopped about a foot short of actual closure.
There's lot's more information about the trenches at this earlier post.