How deep to install double check valve assembly

[mulgarz]

Hi guys,
I am installing an irrigation system for our back yard and I am trying to do it the right way. I have researched a lot about the code for this area (Washington, King county)and it is very confusing on this topic. So after all the research here is what I am planning on doing:

Tap in to cold water pipe from crawling space (3/4 pipe)
Exit the crawling space at 2' depth through the concrete (required depth due to frost line)
install a 3/4 DCVA and a shutoff valve in covered vault (??? nor sure how deep)
feed the manifold from the DCVA (manifold and garden pipes installed at 1' depth)

Now my question is about the DCVA depth does it need to be at 2' or can I install it at 1'
My concern is that at 2' accessing to it might be more dificult. also since the sprinkler piping and manifolds are higher and need to be winterized can the DCVA also be higher.

Thanks for your help.

 

[mulgarz]

More confusion arises. I was expecting my water meter to be also at 2 feet depth as per the frost line requirement and it seems it is less than 1 foot inside of a plastic material vault.
Does this mean I can have the DCVA less than 2 feet deep too?

 

[Sponsor]

 

[WorthFlorida]

The water meter depth is probably OK since you may not get very hard freezes and was acceptable by the inspectors. You can install everything above ground as long as the anti backflow can accept short term freezing with it empty of water. Installing it as you read will make is difficult to the drain the system for the winter. If the property doesn't slope much you'll need compressed air to purge it. If the furthest sprinkler head is below the water pipe level in the crawl space, gravity will help drain the system as long as you open a valve top side to allow air in.

Since you are in the same county as Love Plumbing, perhaps call them.

 

[hj]

In most, if not all, cases any "safety device" with an open vent, which your double check may have, must be installed at least 12"ABOVE the ground.