Jakeb,
I've spent several years working with irrigation systems. A decent drip system would be the way to go with this. I used to take a hard line on drip emitters as you really couldn't see if they were working unless you were on top of them. There's something about being able to see the spray heads getting everything wet... you just know they're working.
Proper installation really helps to mitigate this fear, plus they're pretty dang reliable to begin with.
Below are some Suggestions for those DYI folks out there. There are no hydraulic calculations in here, just some simple suggestions that should provide reasonable capacity for most needs, given a properly protected source with reasonable pressure:
Include appropriate backflow prevention to keep from contaminating your water supply or public water supplies. Believe me there are lots of sad stories out there relating to this issue, and it is much easier than you may think to have an accident which could harm many people. Plus it is not that expensive or complicated to do it properly.
Get a controller - you don't need to be thinking about turning it on manually - it sucks when you forget, and/or forget to turn it off. They are really quite inexpensive for basic functionality.
Consider investing in a 2 wire system if you think you'll need multiple, far-off valves so that you don't need the expense of running 1 wire per valve. Additionally 2 wire systems are much easier to upgrade, but they cost more like all good things do. Drip provides so much capacity (for a given supply) due to the MUCH slower application rate, most can accomplish their irrigation with just a few valves anyway.
Piping and Valves: Dig a 6" trench for, and run, a 1" PVC sched 40 pipe (for durability) as your mainline. Run it in a loop that extends from the output of the water source on a course that passes near the areas that you intend to irrigate, then back to the source. In a pinch you could simply run a pipe from the source to the irrigation areas without the return loop. The loop helps to equalize the pressure, and makes upgrades easier.
Your wires (one white "common" and one red one for each valve) should be placed in the trench directly under the mainline with a service loop at each valve location to allow enough slack in the wire to reach and hook up to each valve. There are 2 wires sticking out of the top of the selenoid on the electronic valves (doesn't matter which one hooks to white or red, just don't hook them together!). Leave about 18" extra for red, which equates to 36" for the white, since it doubles back to go to the next valve. Get some wire nuts and size matched waterproof encasements filled with grease (typically orange or yellow), connect the wires to the selenoid, sink the wirenuts into the grease and snap the encasement closed.
At each watering area ("zone") cut the mainline and install a 'T' to stub out for the valve. Add a 10+" section of pipe extending towards the water zone, which then is cemented into the 1" electronic selenoid valve - I just use the 'slip fit' type to keep it simple, but some use threaded for easier service. You now have a "stubbed out" valve at each irrigation zone. Note that the area under the valve should be excavated to about 10" to fit a small valve box/cover.
Extend the output of each valve towards the zone and install a T with 2 bushings that accept 1/2" drip tubing. Then run the drip tubing in a loop around the irrigation zone and back to the vacant side of the T. If you run the tube close to the tree/plant then you simply have to press the emitter barb through the wall of the 1/2" tube near the base of the tree. If not, insert a barb which accepts 1/4" pipe and run that to the proper location and install the emitter at the end of the pipe. Another option is to install the emitter directly into the 1/2" pipe then install a 1/4" pipe from the emitter to the plant. Depending on how much activity the area will see, you may want to fasten the 1/2" and perhaps the 1/4" tubes into the ground with landscape staples.
If using landscape fabric and/or mulch, install the drip tubing and emitters after the fabric is installed and before the mulch - otherwise you'll have to tear up all that fabric to get to the tubing for mods.
Slow application is much preferred due to evaporation loss and run-off considerations. In general it is good to have 4-5 emitters for the largest tree in the zone. That way you can easily scale back for smaller plants in the same zone, without having to buy all kinds of unusual sizes.
For example lets say the largest tree in the zone needs 10g per week. A readily available drip emitter puts out 2GPH, so a single emitter would take 5hrs to properly irrigate the tree. If you used 5 ea of the 2GPH emitters you could water the tree in a resonable 1hr. Plus, on the same zone with the same duration you could use a single emitter for a small plant which requires 2g per week., Since having multiple emitters provides redundancy in case one gets clogged, having 5 of them would be a good thing for the trees. To provide redundancy for the smaller plants, you would be able use 2ea 1gph emitters, which are also readily available. Too many words for this simple idea.
Hope this helps someone.
KDO
