After watching some landscape design videos from a lady on youtube - Rachel Matthews I think was her name - I decided to try to put more effort into the design of my back yard, beyond just a functional design, which is usually what I do.

I'm now trying to figure out how best to do the sub-surface irrigation design for the two grassy areas.

And while these pictures aren't spot-on, they're not too far off. The grading and elevation changes are a little off on the back side of the lot, but they're the best I've got so far.

http://www.gthomson.us/projects/landscaping/backyard-from-houseview.png

http://www.gthomson.us/projects/landscaping/backyard-from-backside.png

The second one shows what I'm thinking for the running of the subsurface irrigation for the two grassy areas.

The 4 red X's are where I have valves
The white lines (not in place yet) = PVC
The yellow lines (not in place yet) = the Rainbird sub-surface lines - they'd be a little more consistent - my drawing with graphics pens is shaky at best :-)

The lowest point on the property is probably the bottom right corner.

Is this a decent design, or way off what's needed for the sub-surface irrigation?
Suggestions for better ways to go about it?

I think I need a route to the lowest point for a flush/drain/pressure relief valve - I'm thinking I might need two - one for each of the grassy areas. Does that make sense?

Does the spiral make sense for sub-surface irrigation in that one area? That area would be level across it in all ways, and would actually be level with the patio, even though it doesn't look like it.

The back fence width is about 60', in case that helps for reference size.

And yes, that is a UFO hovering above the blueberry bushes - haven't yet figured out how to get rid of it.
And the black space = house with a sliding door going out to the patio.

Any, and all, input is welcome and appreciated.

Greg