SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Never installed a sprinkler system but bought a 25 year old house with 15 automatic valves all RICHDEL. I did replace a rubber diaphram once years ago and a couple of solonoids over the years just simple stuff but now i have more difficult issues and not sure what to do.

First off there is no water shut off valve at the valve head manifold in the rear of the house, so i have to go out to the curb in front and use the 2 foot main water valve handle shutting off all the water to the house in order to work on any valve. Seems to me that a shut off valve at the manifold would be a nice feature to have. Is that not commen practice and if not why not?

Here is my current problem--- there is a leak in the connection between the valve and the backflow preventer. There is a joint between the two and a crack or something has developed underneath so it drips a lot. the valve itself does not leak. This looks like a replacement issue rather than a repair, but I don't know how the two devices are connected togther i.e. a slip joint with glue or screw type joint. Also i cannot determine how the assembly is connected to the vertical PVC pipes? In simple language how do I remove and replace? These are above ground about 8" and easily accessible. I do not see any way to remove them short of cutting them off the pipes. My wife is ready to call the local sprinkler repair man but I won't give up without at least asking first. Any advice appreciated.