Finding the main line

Discussion in 'Irrigation' started by bobw, Jun 10, 2007.

  1. bobw

    bobw LawnSite Senior Member
    Messages: 807

    Well, I'm getting pretty tired of trying to find a leak on a PVC main line. No doubt that there is a leak, but the mainline is in a heavy clay soil and the water is percolating through the ground sideways instead of coming straight up. I can't keep trying to dig test holes looking for the damn thing and there are 0 as builts/etc for this site.

    What is the fastest/easiest way to find the mainline? I'm thinking that renting a wire locator and try to find the control wire is the way to go. Any better ways?
  2. Without A Drought

    Without A Drought LawnSite Bronze Member
    Messages: 1,079

    that is one way to go, although not completely reliable.

    try renting an air compressor and looking for the air leak. i find that to be the easiest way to find a tricky leak

  3. BPC

    BPC LawnSite Member
    Messages: 119

    Using a locator to track the wire is a good way to find the main. Most of the time the two are in the same trench.

    If you are working on a large property finding a place in the main about 1/2 way down from the meter and capping it will let you know what half of the property the leak is on. Then you can keep narrowing it down that way.

    There is also some very expensive leak detection equipment out there. Were you inject gas into the line and try to find the place it is leaking out. This is something I sub out when it comes down to it because the equipment is so expensive.
  4. bobw

    bobw LawnSite Senior Member
    Messages: 807

    This is a fairly large spread out property. I'm pretty certain that the control wire is in the same trench as the mainline.

    I don't think air injection will work for the same reason I can't find the water leak. Everything percolates sideways due to the clay.

    Messages: 18,668

    A solution I have used in this situation is to install a master valve. Take the wires from the closest valve and extend to the new master valve. Find the next closest valve and use it with an add-a-zone to run that valve and the valve that lost its wiring to the master. Or if feasible run a new zone wire to the clock for the master. At least you have an end in sight with this procedure. no telling how long it will take to find that leak. GOOD LUCK
  6. irrig8r

    irrig8r LawnSite Platinum Member
    Messages: 4,553

    A nice sharp tipped probe will find the mainline in a hurry.
  7. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    Or at least another leak depending on the mainline size and wall thickness. But, after some use they get a little dulled so they won't puncture smaller diameter class pipe. :)

    Wonder how the poly boys probe and how does poly hold up to probing?
  8. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    521 it then. When we have large leaks we usually turn the water off for a couple of days. Then, when we turn it back on we will generally get close to the actual leak point (even if it's traveling) by observing where water first appears.

    Some leaks can be narrowed down by looking for telltale washed sand. Sand is the heaviest soil particle and is washed and left behind when the water moves clay and silt particles away.

    Leaks produce different soil profiles also. Soil in an area where water is traveling over it will still be somewhat solid to shovel testing. Areas where water is leaking actually changes the soil structure and that's where you'll get the mushiness when probing with a shovel.
  9. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    Perhaps you could explain how a master valve helps you FIND mainline leaks Pierre? :laugh: :laugh:
  10. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    And using compressed air is... more reliable? :)

    I think if I had to go rent something it would be the 521 and not the compressor. It's easier to carry. :laugh:

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