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How long should I water for?

Discussion in 'Irrigation' started by Gabby, Jul 4, 2010.

  1. SoCalLandscapeMgmt

    SoCalLandscapeMgmt LawnSite Bronze Member
    Messages: 1,941

  2. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,308

    FYI Fimco ... That pic depicts seasonal root growth trend for a cool season turf, not root depth.
  3. Gabby

    Gabby LawnSite Member
    Messages: 140

    Sorry guys I have been busy and did not have time to reply. What is the best way to go about figuring out my replenishment rate? Thanks.
  4. Gabby

    Gabby LawnSite Member
    Messages: 140

    Thanks for replying. Like I asked above how do I calculate my wells recharge/replenishment rate and also my irrigation demand? Environment is cool grass (as stated I am in the northeast - in NY). Wooded area so sun and shade. Some zones are in more sun then others - almost full sun. I understand I need to irrigate less in the more shaded areas. Soil is topsoil/loom and some clay. Again thanks for the replying.

    Messages: 18,668

    Even though Kiril and Wet Boots are both on my ignore you are far better off talking to Wet Boots on well stuff and if you live in NY asking a turf hating CA how to water may not be one of the better decisions you make in your life Gabby. Try Walkgood or A-1 or Greenmonster.
  6. Gabby

    Gabby LawnSite Member
    Messages: 140

    So I went out and ran a test - you guys tell me what you think. Again my well is 225' deep and when drilled was logged as a 20 gpm well. I pulled the cover off the top of my well and stuck a 30' tape down it while looking with a flashlight and at exactly 20' from the top of my well casing the tape toughed the water. I ran one zone manually for 30 minutes. Zone 2 which is in the most sun during the day. I figure WTF may as well water that area while I am experimenting. After the 30 minute run was up and I stuck the 30' tape down in it again and obviously I could not touch water in the 30'. I waited 30 minutes and measured again. The 30' tape touched water at 22.6' so in that 30 minutes the well recovered back almost where it started minus 2.6' which is about 15 gallons of water. 6 inch well casing so .25'^2 * 3.14(pie) * 2.6' = 2.04 cu. ft. 7.48 gallons per cubic feet so about 15 gallons. Being I watered for 30 minutes with four 1.6 gpm heads I figure I used 192 gallons of water and recovered back 177 in 30 minutes if my thinking is right. So if it recovered 177 gallons in 30 minutes it recovered at about 6 gpm in reality. What do you guys think? Is that right?
  7. Gabby

    Gabby LawnSite Member
    Messages: 140

    Forgot to add. I also put out a small cup in the center of the zone I manually turned on and let it fill while the zone ran. The cup was about 1-1/4" high and about 2" in diameter. Probably not the best thing to use but all I could find at the moment. In the 30 minutes it filled about 1/4" so if the cup was a little bigger maybe it would have filled to like 3/8" give or take. Also I understand this was only one zone so there was no over lap from one of the other zones which may or may not be the case when multiple zones run. What is the best thing to use to measure with, where is good placment to put measure cups and would there be overlap from other zones? Thanks for any and all replies.
  8. bcg

    bcg LawnSite Bronze Member
    from Tx
    Messages: 1,835

    I didn't read the thread thoroughly enough to answer anything else but, 1/4" in 30 minutes for a rotor zone is right on the money. We estimate them at 1/2" an hour until we do an audit and find out otherwise. In a good design, they're usually pretty close to that.

    The right way to get your PR and DU is to set up straight walled containers of equal size in a grid throughout the zone. After that, there's some math involved to calculate your precipitation rate (you basically average them out) and the distribution uniformity (which is the more important number at first). I can't remember the formula for calculating DU and I'm too lazy to look it up right now.
  9. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,308

    What you are attempting to determine is a little more complicated than that. If your wells initial discharge rate was logged at 20 GPM, then you are probably safe if you don't exceed 10 GPM on your irrigation zones.

    One cup won't cut it (audit or otherwise), nor will it give you an accurate measure of what the zone is demanding from the well. A better measure (without actually measuring flow rate) would be to take an inventory of the sprinklers and nozzles for each zone, then you can look up the nozzle discharge for the average pressure the system is operating at.
  10. Gabby

    Gabby LawnSite Member
    Messages: 140

    Each zone has 4 Hunter PGP 1.6 gpm heads so I am using 6.4 gpm per zone so I should be OK - correct?

    7 zones with four 1.6 gpm Hunter PGP heads per zone. Operating pressure is 50 PSI. Where can I look this up? Thanks.

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