Sodwall bunkers are both expensive to build, as well as to maintain, but not as much to maintain as the older courses. Technology has allowed sodwall construction to have a more reasonable long-term sustainibility, mostly because of a few things: Although on the surface it just looks like stacked sod, there is a lot going on behind the edge. Many sodwalls are reinforced with steel bars to avoid structural breakdown, and most have some sort of geotextile screening to prevent particles from falling out and breaking down the sharpness of the edge, as well as preventing weed growth. I haven't seen where there is irrigation integrated into the faces, but I can only say it's both possible and likely. In most cases there is some additional irrigation required to maintain adhesion, if the soil profile is insufficient.