I had a pool removed and backfilled from within a 4' cmu block retaining wall. We are putting in pavers with a nice long 15' x 4' cutout which we intend to keep plants and trees (screen enclosure friendly). My quagmire is, obviously I need this irrigated, hand watering if I must, but if I want to extend my ground level sprinkler line onto the raised cmu block wall, how can that be done. I wouldn't think drill a hole through a retaining wall would ever be a good idea. A soaker hose from my spigot 25 ft away would also pose an issue since I will have a screen enclosure.