Why do sprinkler heads sink?????

Discussion in 'Irrigation' started by jonspolaris, Jul 20, 2001.

  1. jonspolaris

    jonspolaris LawnSite Member
    Messages: 130

    well i have another question in regards to my moms irrigation system.

    i was looking at the sprinker heads an many of them, not all, are sunken below the grade line by about 2". they were not installed that way, they have sunken over time.

    the soil is an organic topsoil, and then sandy base.
    the sprinklers are Hunter PGP.

    one neighbor said it was the Lawn contractors lawn mowers. They uses eXmark lazers. He sais that the weight of these machines was pushing the heads down. is he full of it???

  2. racerdave

    racerdave LawnSite Senior Member
    Messages: 260

    yes he is full of it.

    Have you noticed any settling of the trenched areas that the piping is running in? Because that is what it sounds like to me. The other might be if someone has been aerating the lawn,that will push down the heads.

    How old is the system?

  3. jonspolaris

    jonspolaris LawnSite Member
    Messages: 130


    i have not noticed any settling in the trenched areas, but only the main line is trenched. all the other lines were put in with a vibatortary knife.

    not all of the heads have settled, but some have. its just like they sunk 2".

    the man who thinks its the lawn motors doing this is 84 and thinks whatever he says is correct. He also doesent want anyone to "scare him with the facts".

    they havent arrorated the lawns, so thats not a problem.

    the first zones were put in 6 years ago, but the last zones are about 4 years old.

  4. racerdave

    racerdave LawnSite Senior Member
    Messages: 260

    Are the heads that have sunk at the end of the zones?

  5. jonspolaris

    jonspolaris LawnSite Member
    Messages: 130


    I dont know if they are at an end of a Zone. it amost imposible to tell. they dont run in a straight line.

    I found out that the yards were arreated, but it was only 2 times in 5 years.


  6. greasemonkey

    greasemonkey LawnSite Member
    Messages: 57

    is it possilbe that the heads that have sunk are the ones with the lowest elevation compared to the rest of the zone that they're in?...often times zones with elevation changes will drain out the lowest head in the zone when they're shut off. This water slowly flowing out of the head after the zone runs could cause settling and sinking. If you do determine the elevation change to be the culprit you can install heads with check valves. Hunter offers checkvalves in just about every model line and they sell a stand alone unit they call it the "HCV"...it has 1/2" female threads on both ends and can compensate for up to 20' of elevation change.

  7. Currier

    Currier LawnSite Senior Member
    Messages: 564

    Maybe since it has been a number of years since the system was installed, the soil and grass have built up around the heads. You have growth and growth takes space. The heads do not grow and so they appear to have sunk below the soil lin when in reality the soil line is simply growing up over the heads.

    You gotta love the old blame the lawn guy for everything comment !
  8. jonspolaris

    jonspolaris LawnSite Member
    Messages: 130


    I think your correct, The Lawns are irrigated every day,lately they have been irrigating 2 times a day because of the dryness. They also have Chemlawn do there fertalizing,Yes I know, Chemlawn is bad.

    Ill have a better chance of winning the Lotto than trying to tell her neighbor that the grass is growing around the Heads. He told me he "knows" that they are sinking because of the lawn mowers.

    If i Proved that it was not the Mowers that were sinking the heads, then he would get mad and go into his house, hes 84.

  9. HBFOXJr

    HBFOXJr LawnSite Bronze Member
    Messages: 1,712

    I'm with Currier.

    Do you think the sidewalks, driveway and curbs are sinking? Grass will build up here in New Jersey under almost any but the poorest maintenance. It's natural. It's one of the reasons sprinklers should be installed with seing pipe or swing joint assemblys.

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