My backflow prevention device failed over the winter (nice large split, as you can see). I checked with the local city, and they won't let me replace like with like, so I'm going to install a Wilkins 720A pressure vacuum breaker instead; here's my proposed design (the unions are so that I can remove the PVB in the winter). Inflow is on the right-hand side, and the sprinkler system will be on the left. This is culinary water, but not connected to the house. Here's my question; as you can see in the photograph, the underground input and output are on black PVC (I think) pipes, 1". Can I use a similar method of connection (Jubilee/hose clips) to connect to the 1" schedule 40 pipe, or is there something else I should use? If I do use the hose clips, can/should I lose the box and bury the pipes (for support)?
I have to get this inspected, and I want to do it correctly the first time, rather than get rejected for something silly like a pipe connection.