Boon's system has two components: each bench has at least one, maybe two "pop up" sprinklers. They're in the middle of the bench and spray out.
But those may water only the tops, and the sides of the trees facing the sprinklers, so he has a second system to water the back side of each tree. I don't know the name, but there's a central hub and the plastic diffusers are each connected with tubing. The diffusers are directional, and they're either stuck into the soil and pointed back towards the trunk, or there are little holes drilled into the wood bench where the diffuser is placed.
The system is on a timer, and each bench gets a minute or two. In the summer, twice a day. Spring snd fall, once. Winter, maybe just hand water. When a bench goes off, the whole bench gets watered.
Right now, however, Boon has an apprentice, so the trees are getting hand watered!