Hi EarthResarcher333.
Re post 3718:
You have a point and I rescind the claim that the concrete chunk does appear to be from one of those extra thick sections. I dont know what part of the spillway it came from.
My point was that most smaller chucks of concrete got washed away, and that one didnt, plausible due to its weight and thickness. It did certainly enter my mind that this thickness could be do to post construction void filling.