Installing sprinkler shut off valve below frostline

Discussion in 'Irrigation / Sprinkler Forum' started by Tubal, Apr 17, 2012.

  1. Tubal

    Tubal New Member

    Apr 17, 2012
    Salt Lake City, Utah
    Hi all.

    I'm attempting to put in a sprinkler system in Northern Utah where the frost line is approx. 36" below ground.

    The house is around 30 years old, and at one time there was another sprinkler system in place by the previous owner, but it has long since eroded so I'm basically starting from scratch.

    The water main comes in to the house and is buried about 36" below ground. The old owner had his sprinkler system tied into this main about a foot back from the house, and all that was remaining was a plugged 3/4" tee. So that is my water source.

    I've dug down to the tee, and attached some pvc to run up to ground level with a ball valve as my sprinkler shutoff valve, and that's where I'm at now.

    I'm thinking that this isn't going to work, because it will freeze and break in the winter. Am I correct in assuming that, and if so, is there a way to keep this from happening? Could I put the shutoff valve in a valve box 12" below ground, or would I need to install a valve 3' below ground? How is this normally done?

    Thanks for any help.

  2. mike1059

    mike1059 irrigation tech.

    Jun 6, 2011
    irrigation tech. for a landscape company
    Portland, OR
    although I'm unfamiliar with the codes in your area, it's best if a shut-off valve and backflow preventer are installed at 36" inside a valve box for access then bring your line up to 12" for your electric valves and station lines.
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  4. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    The backflow preventer must be certified annually, so you don't want it 36" below the the surface. My supply line is 5 feet deep. The irrigation side tees there and goes into a Muller stop and waste valve. Then it come to just below the surface and is connected the the BFP. From the BFP, it goes about 30 feet toward the house when the manifold with the zone valves are located. The controller is in the basement just opposite the manifold. I remove the BFP in the winter just to make certain there is zero change of a little water freezing and breaking it. You have to have the correct type of BFP to mount it below ground level, but they do exist. Your local area may or may not abide by Federal laws pertaining to inspections, but it should certified as functioning properly each spring. Mine is scheduled this week.
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