BUT... the picture in post #2273
http://www.freerepublic.com/focus/news/3524221/posts?page=2273#2273
certainly does appear to be the other way around...
I just don’t really know.
The only other thing I have to contribute at this time is that
somewhere ... outside of the sidewall, there would have been a
transition from the perforated pipe to a non-perforated pipe.
There is a slight "flaring" of the remains of the elbow in the spillway wall. This also indicates the bell couplings were aligned appropriately (upslope) - at least for this "missing pipe" section.