Unbury,

Here is what I would do. First, locate main line valve by digging down around the valve manifold to expose the pipes(in pic #1). See the pipe that connects all the valves on the inlet side of the manifold; that is your mainline. Another method is to use a small metal pipe held in your fist(poor mans stethoscope) to listen to water moving through the pipes. Turn on each valve manually by turning the solenoid and listen(record what lines comes on with what valve). The line that always makes noise is the mainline. I would replace the whole manifold section. That is all the automatic valves and piping. I would use the the in-line auto-valves instead of the ones you in the pics. This change would decrease the height of your setup(make them invisible). Place the manifold and auto-valve in a irrigation box with lid 1/2" above the surface of the ground. Each in-line auto-valve should have unions on both sides for easy replacement. I would install a main shut off with a Vacuum Breaker that sits above the highest irrigation head. That would be the only visible part and give easy access to shutting off the irrigation system. If the controller is 10 years old or 20 yrs replace that as well. It is easy to do yourself and a good one costs about $50 for a 6-zoner. Good luck. JMHO Aloha

Thanks for the reply. I really do appreciate your assistance.

I'll try the metal pipe method today. Bare hands only didn't work, as the pipes are all touching each other.

Your suggestion to "replace it all" is exactly what I would've done on my own, had it been easier.

I should've been clearer, as I would've dug down by the 1st valve had it been easy enough. The 2nd picture above IS only about 1 foot away from the 1st valve, just the other side of the fence. The room shown in the pic #1 is the entirety of the room available. It is too tight to do any real work in there (even if I remove the junk shown). To the right is the house, to the left is the cement slab with a big shed, to the front is the fence with metal post topped off with cement running just underneath it!

It took over an hour to remove just 3" of rocks from around the valves; we didn't even make a dent in it.

You can't tell from the pics the whole area is very secluded so I don't care if it's ugly.

Question: Do the metal+pvc manifold lines need replacement every so often, just like the valves do?

If so, then I guess I'll bite the bullet and tear down the fence section and break the cement, in order to clear out the rocks and replace the manifold. The wiring is looking pretty old, too. Becomes a much bigger project at that point.

If the pipes rarely go bad, I guess I'll just skip the Master shut-off idea and replace the valves. I also have a new 6 zone auto-timer ready.

Does the last pic look like the only materials needed for a valve-only replacement?

Thanks

CE,
I am glad you responded, here are some additional thoughts:
1.What is the distance between the concrete slab and house slab in the first pic?
2. Rent an electric spade with a shovel or point attachment. Or buy a long heavy steel pointed breaker bar. Both items will make short work of rocks around manifold.
3.This is an in-line autovalve. They are quite small compared to what you show in your last pic. This link is just a sample of the valve. Any brand will do. http://www.rainbird.com/homeowner/products/valves/CP-CPF.htm
4. If your manifold is started and ended with a pvc union-type coupling. Your system can be put together outside the hole and fitted in as one unit and screwed in place. Does take some planning though.
5. PVC pipe does get more brittle with age but if let completely undisturbed will last a very long time but if it not buried deep enough will be disturbed by moderate surface activity. Also internal shock from high velocity movement of water from high pressure can cause shock breakage over time.
6. I recommend a master shut-off valve with a vacuum break/backflow prevention device attached as you have shown in the last pic. You only need one per system if you only have one source.
7. Think about stacking of manifold lines on top of each other versus side by side if there is not enough room, aesthetics aside.
Just my humble opinion(JMHO). Aloha

lehua13,

If you're still around, I'm sorry I never responded .. I guess email notifications were off for that period b/c I never got a message.

I ended up just replacing two of the valves and still have not put in the master shutoff. But the pvc is showing more age and I'm replacing the shed next year so I'm saving your instructions for this fall.

Thanks so much for taking the time to help me.

Can I just exchange a rainbird for a Tora as long as my GPM is the same?