On Jun 12, 7:19 pm, Ken wrote:
1) How deep should I dig my trenches for my lateral lines? I live in
the Seattle area; I'm not sure how much of an issue freezing is.

Freezing isn't an issue. In areas where it freezes the system are
either made to self drain or else blown out with air before winter.
I'd suggest if your going to trench, go 8". That's about the depth of
a rotor head. And that way the pipe will be deep enough so that you
can aerate the lawn and not run the chance of hitting a line. The
pros use equipment that basicly pulls the pipe and in hard soil areas,
they probably wind up half that depth in many spots.


2) I notice that sprinkler head bodies come in varying heights. I'm
just going to be watering a 350 sq. ft. lawn (no shrubs) and I'm
wondering what height I should purchase? All of my radii are 10' or
less.

Should be app info on the manufacturers websites that give a guide.


3) Double-check valves seem to be sized to fit a range of sizes. I'm
considering the following Conbraco unit; will it accomodate my 1-1/4"
PVC mainline?http://www.sprinklerwarehouse.com/1-...ck-Valve-Assem...

Don't know, fitting size should be on the spec sheet.



4) I had a plumber tell me that I could bury my double check valve in
a valve box underground. All of the models I see online, however,
seem to require them to be mounted a foot above the ground. Are there
types that can be buried? I don't mind putting forth a little extra
money/effort to protect my potable water.

How does burying it do anything to protect your water? The backflow
devices I've seen on systems have been mounted above ground, where the
pipe exits the building. Seems the easy and logical way to do it to
me, unless there is a specific problem. Usually, they are just
hidden by shrubs. I'd check the local code as they may have reqts as
to specific type of device, location, etc.


5) Can someone recommend a Seattle-area retailer that carries
sprinkler heads, valves, and accessories that are of higher quality
than one finds at Home Depot?

Thanks for any guidance!

Here on the east coast, the local plumbing supply sells them. Check
there or under irrigation supplies.