above ground irrigation in a suburban setting

I would like to know if anyone is doing above ground irrigation piping.    

I lost several of my underground pipes to earth movement over changing seasons and maybe some even to roots from my larger fruit trees.
 
I need to run the water lines on the top of the soil but I can bury them in chips since I covered my backyard in 10 to 12 inches of wood chips.  

I have a 12 valve controller and 9 of the slots will be available since I am doing his in the backyard.  I like to automate as much as I can so if I have to travel for work I do not have to worry.

I have about 1/3rd an acre so this would be an overwinter effort.  

Are there any ideas on best way to do this?  I was originally thinking of a metal line so it would last a real long time.  I could run a low power line in parallel with the water line and branch off the main line to provide a valve at various spots around the yard.

We tend to have droughts that last 60 to 90 days at times so I need to water the trees but during normal weather I still need to do the veggie garden and small beds a couple times a week.

I am hoping to see if anyone has gone down this path and can send some good advice and warnings my way.  Thanks

I have 25 various fruit trees on 1/3 of an acre of my ranch.  I set up an above ground irrigation system, mostly in case something came apart, I could fix it easily.  It is out of 3/4" pvc tubing, and from those main lines, I have run 1/2" tubing connected to a drip ring around each tree.  Each tree has its own valve on and off if needed.  It was pretty easy to design and set up, and I ordered everything online from drip depot.

I have had a lot of PVC go brittle and break with the slightest strain.  The gray stuff is okay in the sun but has chemicals that you do not want on your food.
I may look around and see how much the metal tube costs.  I have about 400 foot to ring my backyard and also put a line into my hoop house.