Another thread made me think of this. However, I didn't want to take that thread off topic, so here I go. Has anybody ever seen water run out of a drain pipe that they installed behind a retaining wall? I'm not talking about a little trickling out, I mean water running out. Enough that you think," Damn, I'm glad that I installed that pipe." I went through the NCMA certification last year. The topic was discussed while reviewing the NCMA guidlines for installing drainage pipe. There were probably forty other contractors there and not one had ever seen water running out of a drain pipe installed behind a retaining wall. I'm not suggesting that it isn't necessary, but like everyone else in that class (including the instructors) I wonder. I've gone back to jobs during heavy rains, the days after heavy rains and nothing. I still install it on every job in order to cover my a**.