Lawn irrigation systems and wells

Discussion in 'Irrigation' started by GripB, Aug 10, 2004.

  1. GripB

    GripB LawnSite Member
    Posts: 215

    Homeowner here wanting to know the pros and cons of having a lawn irrigation system installed/connected to my well? (tired of dragging *****ing hoses and sprinklers arround)

    --10gpm well

    --1/2hp Grundfos well pump

    --Would like to sprinkler 40,000 s.f. of lawn

    Please comment/question. Thanks in advance.
     
  2. Mdirrigation

    Mdirrigation LawnSite Silver Member
    Posts: 2,471

    Well you dont have to move hoses anymore.
     
  3. jerryrwm

    jerryrwm LawnSite Bronze Member
    Posts: 1,274

    Grip,

    What is the pressure at the well head or pump? And what is the drawdown and recovery rate of the well?

    You are going to need a boat-load of zones at the flow you have available. At 10 GPM you might be able to run 3 - 3GPM rotors or 4 - 2 GPM rotors at a time if the pressure is available, and you size the pipe properly.

    It is still going to take a long time to water nearly an acre. It takes a bit over 27,000 gallons to put an inch on an acre.

    You're gonna need a big controller!

    Have you considered a couple storage tanks and a centrifugal pump? With a float switch, you could water a lot of area and not run out of water with the well refilling the tanks as your system ran. And your zones could be bigger and the controller smaller.

    Jerry
     
  4. GripB

    GripB LawnSite Member
    Posts: 215

    Jerry,
    Thanks for the reply. I'll try and locate the pressure at the well pump and the drawdown/recovery rate (I guess I'll contact my well driller). The lawn is 3 years old. It's a 70% rye 30% Kentucky Blue lawn and I was planning on aerating/overseeding with 100% Kentucky Blue this fall. I was prepared to spend a few G's on an irrigation system, but it sounds much more involved and much more than a few G's. Am I right? We are also concerned about potentially drying up our well.
     
  5. irritek

    irritek LawnSite Member
    Posts: 3

    The pressure and GPM have very little to do with your design. of corse the pressure is good its off a pump prob.w/a 40/60psi pressure switch. As far as the GPM I have installed big systems w/4-5 heads per zone 7-10 GPM on a 3GPM Well. You will have to use a controll panell w/ programable delays such as Rain Birds esplx clock.and make sure you know the accurate replenish rate of the well. NOTE: The head pressure in wellhead should be equal to the operating pressure of zones. I recomend an good size pressure tank to extend the life of your well pump.
     
  6. jerryrwm

    jerryrwm LawnSite Bronze Member
    Posts: 1,274


    What??? You're gonna have to explain more in depth how you run a zone with 7-10 GPM on a well pump that does 3 GPM.

    I'm also a little more than confused about the statment that pressure and GPM have little to do with design of an irrigation system.

    Pressure tank is fine, but a good pump start relay will be better on the pump for many reasons, especially in the prevention of short-cycling.

    Have I been missing something these past 20+ years?

    Jerry
     
  7. Fatheroftwo

    Fatheroftwo LawnSite Member
    Posts: 19

    I believe I'd start with a bigger pump and a new well. Spend $$ here or in the yard with more pipe and Zones.
     
  8. jgc8fan

    jgc8fan LawnSite Member
    Posts: 65

    The pressure (PSI) will tell you what GPM a head will produce (usually a chart printed on the head label) The amount of GPM is additive like voltage in a circuit. You will subtract GPM for each head installed, so... If you have 60 PSI, and 12 GPM at the well head, and your sprinkler head operates at say 3 GPM at 60 PSI then you could probably put 3 of these heads on a zone, but the pipe you use will also restrict your GPM. I think at 60 PSI 1" PVC tops out at 15 GPM, and 3/4" at 12 GPM. And the reason I said 3 heads and not 4 is because you always want to leave a little in reserve so that the system doesn't strain or lag to start up... Even when the heads are pressurizing the timer on the controller is already ticking so the longer it takes a zone to pressure up is losing watering time. And... If all that didn't confuse you enough... The GPM the heads use depends on the spray pattern. So if you have a gear drive that draws 3 GPM @ 60 PSI with a 360 degree (full circle) pattern, and you were to adjust this pattern to 180 degrees (half circle) then you are only using 1.5 GPM @ 60 PSI on that head. Therefore... If you are not using full circle patterns (like on the edges of the yard) then you can sneak extra heads into the zone. :) Then comes the issue of whether to use poly tube or PVC pipe. ;)

    And the answer to the original question is... Pros... fully automated watering... No dragging hoses... No worrys. Cons... Initial cost... Regular maintenence (cleaning filters on heads etc...)... Check your codes before trying to put one in yourself... Best to leave to the pros, or possibly wind up with code violations and fines. (speaking from experience on that).
     
  9. GripB

    GripB LawnSite Member
    Posts: 215

    "Con"...Initial cost. Ballpark range what should I expect to pay to irrigate 40K? And back to the top, our initial concern, is there a risk irrigating from our house well?
    I would have a pro install and maintain this.
     
  10. jgc8fan

    jgc8fan LawnSite Member
    Posts: 65

    It all depends on your area, and the local rates... Around here a typical yard 1/2 acre lot runs about $2300 for a 3 zone system. It's not too bad actually when you think about the benefits.

    Most houses around this area usually have wells installed just for irrigation. No problems, and their grass "seems" greener than irrigation from city water (no chlorine in the well water, and more minerals for the grass). The only risk I have seen is that if you have a lot of metals and sulphur in the well it can stain pavement and the walls of your house with a rust color. This can be solved by making sure your patterns are set to keep the water from spraying the house or pavement (you don't want to water there anyway). The heads will overspray from the head itself a bit, but if it's built to code then the heads should be far enough away from walls and pavement anyway (In FL heads must be 12" from walls, and 6" from pavement). Other than that... You should be fine... If you get stains (Yes... sometimes you may get stains on grass usually from heads that need the filters cleaned) you can always add a water filter at the well to take the metals out of the water before going to the system.

    BTW... Just so you know... I'm not an irrigation tech, but I've done a few systems on the side, and am studying to take the test next year.
     

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