My overflow on my 4 acre pond is a 4' oval drain pipe(horizontal). I have put a 5' x 8" solid cement bench top in from of the pipe this summer to raise the water level 8"(worked great). In order to have a draw down I need to bust up the cement top. My question is, I would like to make somthing to put in its place that would make the draw down easier. Would treated 2x8s work with some kind of sliding door or any other ideas that are out there....thx...CT