GPS for valve location documentation

Discussion in 'Irrigation' started by PurpHaze, Oct 9, 2005.

  1. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    Anyone use, or know of someone using, some type of GPS system to document the location of valve boxes? On athletic fields we bury valve boxes several inches deep (sometimes with metal plates laying on top of the lid) to allow turf to grow on top of the valve for safety reasons. (We also lose valves at ground grade in other site play fields as grass creeps over them.) I measure (triangulate for accuracy) and then do up a schematic on CAD. But you know how things are when trying to locate a lost valve even if using measurements, metal detector, probe and/or a 521.

    How accurate is GPS and what would a decent hand-held system cost? I know there are some very large irrigation consulting companies using GPS to aid in plotting and designing but those systems would never fly with my bosses because of their cost.
  2. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    A quick google search suggests that Consumer GPS are supposedly accurate down to about 15 meters...Which is probably far to inacurrate for your needs.
  3. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    I was looking at some and came up with about the same. That's a lot of turf and I can be that accurate just by guessing. Another reason we use rectangle boxes; more square inches equals better chance of locating. :D
  4. HooKooDooKu

    HooKooDooKu LawnSite Member
    Messages: 70

    The typical GPS will cost about $100 - $400 (depending upon the number of bells and whistles you want).

    The typical accuracy is about 20 feet. If you are in an area that you can receive what some might call "correction" signals, then you MIGHT get as accurate as 3-4 feet (best case but unlikely scenario).
  5. DGI

    DGI LawnSite Member
    from SE Mich
    Messages: 173

    Why not just use a wire tracker? Also, burying rebar to mark locations later to be found by a metal detector seems to be common in other underground trades.
  6. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    Ghosts. As good as I am with the 521 there are still a lot of false positives out there. (My ears hurt when I get near high power conduit.) Following the wire is one thing while locating an exact valve is quite another. Also, sometimes it can take quite some time. Spent two hours this afternoon using the 521 in an attempt to locate a valve that hasn't been seen in twenty years. It's an extra valve that now has to be used since parking lot construction has changed system configurations. One of ten extra wires in the controller go to it and I have no desire to trace them all. Maybe I'll have to though. :cry:

    Ever metal detect on a school site? You'll find ever nail, coin, paper clip, screw... everything BUT what you are looking for. Only time I've seen it work great is when a large enough plate is placed on top of the box lid. It sends up a hugh signal on the detector. :D
  7. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    Maybe when they get it down to 3-4" it might be worth it. :p
  8. Critical Care

    Critical Care LawnSite Bronze Member
    Messages: 1,654

    I would think that with good triangulation coordinates and a decent transit you could get right on. You could always use a couple base markers or monuments to shoot off of.

    As far as the GPS route goes, that too should at least get you into the ballpark. Farmers use GPS linked computers on their tractors to automatically regulate the correct amount of fertilizer being applied to sections of their fields.
  9. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    I finally found that dang valve I was looking for. Probed within inches of it several times over two days and finally hit pay dirt. Had to dig up the 3" main in a direction I figured the valve was and then cut into the common wire and used the 521. Sent out a stronger signal closer to the valve and led me right to it.
  10. Critical Care

    Critical Care LawnSite Bronze Member
    Messages: 1,654

    See... that was simple, wasn't it?

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