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Thread: Irrigation well question (low flow rate)

  1. #1
    DIY Junior Member symatic's Avatar
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    Default Irrigation well question (low flow rate)

    First time well digger here located in Florida. Im in a world of sand

    I'll explain what I have done and what issues(if any) I am having.

    Pump:
    Flotec thermoplastic 1.5HP
    1.5" inlet and outlet
    dual voltage set at 115V(running on 12guage extension cord for testing)

    Static water level roughly 7-8ft

    1st setup:
    Jetted 2" casing 30ft down
    Inserted 1.25" suction pipe w/ 5ft well point
    At top of suction pipe used a 1.25" to 1.5" bushing(all pipes now 1.5"
    Attached check valve then to pump
    Flow rate 7 GPM

    2nd setup:
    Using same setup as above I jet another 30ft well point 6ft away.
    Manifolded them equal distance apart and all 1.5" pipe
    Attached check valve after the T
    Flow rate 7GPM

    I expected a higher flow rate on the first pipe. I read multiple points will produce more water. They are producing the same flow rate?

    The check valve holds tight and makes a nice vaccum sound when unscrewed. Stays primed overnight(2 days is the longest i have let it sit without fiddling with it).

    Connected a pressure guage and it read zero. This cannot be as it can run two giant impact sprinkler heads at the same time. Will exchange guage tomorrow, and post back results.

    Next thing I have noticed is a slight gargling sound in the pump after 15 min or so of running. Read it may be cavitation and will try to adjust a few things to remedy that as to not cause pump damage. It is very slight, and adjusting the ball valve only makes it sound worse.

    I know I provided alot of information(hopefully clearly) and I appreciate anyone who takes the time to read this. Hopefully you will notice something that I am overlooking and/or provide some tips to this beginner.

    Thank You,
    John C.

  2. #2
    Jack of all trades DonL's Avatar
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    Welcome to Terry's Forums Symatic,

    I believe that is a Sprinkler pump and not a jet pump, and has a rated max lift of 20 feet.

    How are you driving the jets in the wells ?

    That GPM may be all that pump can deliver with the way it is installed.

    Have a great day.


    DonL
    Last edited by DonL; 05-25-2011 at 06:12 AM.
    Theory only works perfect in a vacuum.

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    DIY Junior Member symatic's Avatar
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    Thanks for the reply.

    I thought the lift is from the static water level.

    I'm using a sprinkler pump because I plan on installing a system. It has instructions for well point installations and it is used in this area quite often.

    Reguarding jetting, I used a T and attatched two hoses to a 2" pipe. Worked well till about 10 feet. Then I put the hose inside the pipe and twisted it down displacing the sand/dirt of the top.

    So I might need a higher horse power pump?

    John C.

  4. #4
    Jack of all trades DonL's Avatar
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    If the well pipe can maintain the static level with the pump running, then you would be fine.

    But you may not have enough water capacity to run that pump at full capacity.
    I don't think more Horsepower would be the answer, That pump has the ability to make more than you are getting, but does depend on the water level and the pressure you are working it at.

    I guess you are really just running two wells in parallel.

    Enjoy your day.


    DonL


    P.S. That pump is rated for FLOW AT 10' LIFT and 30 PSI: 45 GPM, and almost 20 amps @ 115 VAC. Keep your extension cord short.
    Last edited by DonL; 05-25-2011 at 07:39 AM. Reason: P.S.
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  5. #5
    DIY Junior Member symatic's Avatar
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    You are correct I am running them parallel. I used the term jetting to describe the method I used to put the casing down.

    I was hoping it wasn't a water capacity issue. Maybe sitting in some less porous sand. Possibly I could pull the pipe up a bit to determine that. This will be last case senario.

    Was planning on running it at 230 volt and putting it on a disconnect switch. The extension chord is probably 25ft, I'll set it up to run at 230, maybe it is not getting enough power.

    Thank you
    John C

  6. #6
    Jack of all trades DonL's Avatar
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    You say ; "slight gargling sound in the pump after 15 min or so of running"

    If the pump is making a different sound after running a while it may be sucking air, maybe the wells can not keep up, for the flow that you want to get, but the pump should be capable of more flow. That is if the water is available.

    You may need a different screen size/point length to get more water, if that is the problem.

    I am not sure how much sand that pump can handle safely.

    Good Luck.
    Last edited by DonL; 05-25-2011 at 09:08 AM.
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  7. #7
    DIY Junior Member symatic's Avatar
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    The pressure gauge read zero, and I thought that would indicate an airleak. But it seems to have enough pressure to power the impact sprinklers i connected.

    I was thinking I did something wrong that would be wildly obvious. Sounds like I'm back to the drawing board.

    I'll try to test each suction pipe seperately to determine a possible air leak. If it turns out that it is air tight I have to start moving them around and that is what I was trying to avoid. Since it is pulling 7GPM it means I am in water, but I could be in some less porous material(its not sitting in large grain white sand) I'm trying to rule out the easiest things first before I go ahead and start this process over.

    Thanks again
    John C.

  8. #8
    Jack of all trades DonL's Avatar
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    If the gauge is working, then the volume of the sprinklers would have to be more than the well can supply.
    But you would have to get some reading, I would think. (If the sprinklers are operating normal)

    That pump is made for large volume at 30 PSI. Did you tap the meter to see if it was stuck ?

    A leak could be a problem, but some indication of pressure should be on the meter, if the meter output is not restricted and the sprinklers are operating normally.

    If You remove the meter and power the pump on, you should see if the meter is getting the water pressure, You should have a good stream of water, from the meter port.

    What is the flow rate of your Driven Well Points ?


    DonL
    Last edited by DonL; 05-25-2011 at 10:37 AM.
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    DIY Junior Member symatic's Avatar
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    Ill fiddle with the pressure gauge when I get home. The output at the time of test was an 90 degree elbow to a ball valve and a straight pipe with no restrictions. That is how I was measuring the output. I closed the ball valve slowly to see if that would create more pressure and the gauge bounced a bit, but I think it was just moving with the vibration not pressure.

    As for the rate of the driven wells I did not actually measure it. I would fill it up with the hose and it would rapidly go down. When I was putting it down at times it would absorb more water then I could flush down, but that was around 15 to 20 feet. Missed the last part about sand in the pump. I'm not seeing sand coming out at all. Only thing is the water is orangish but that seems to be a standard in the area. May try to back wash the pipes, maybe some clogging is taking place.

    John C.

  10. #10
    Jack of all trades DonL's Avatar
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    John, I think that Under ideal conditions, a Brady 1 1/4" well point can deliver between two to three gallons per minute per linear foot. You may not have a ideal condition, or you may be correct about a restriction.

    If you are measuring pressure with no restriction on the output, then close to 0 (Zero) may be normal, as the meter port is on the output side on that pump, and would need some restriction on the output to see a reading.

    Maybe one of the Well Pro's will stop by and give you better clues.

    I am sure that you will get it to work with a few modifications.

    Have a good afternoon.


    DonL
    Theory only works perfect in a vacuum.

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    DIY Junior Member symatic's Avatar
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    I like that word "ideal".

    I guess I should slap that pressure meter back on there and try to get a reading.

    Thank you for all you input.

    John C.

  12. #12
    Porky Cutter,MGWC Porky's Avatar
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    I see several problems. (1) irrigation pumps pump lots of water at little or no lift. You state that your static water level is 7 to 8 ft. Your pimping level (what your pump sees) is much more. The only way to check this is with a vacuum gage on the suction line at the intrance of the pump suction. Any vacuum reading more than 18 inches is a problem. (2) Even though pump companies give information on irrigation pumps pumping from wells, it is misunderstood because of the unknown pumping level. (3) The Cone of Influence caused by the two wells 6 feet apart causes the pumping level of each well to be greater. NOTE: Thats the reason for multiple dewatering wells to dewater the ground before construction! Wells pumped together should be as far apart as possible. (4) Coarseness of the sand has little to do with anything. (5) Any 1.5 hp motor will do better when operated on 230 volts. (6) The gurgling sound is probably cavitation caused by gradual increased lift vs gallons per minute. (7) You may or may not see much pressure on the output of the pump!
    Sorry to be such a long response but you brought up a lot of questions and possible problems!
    Porky Cutter, MGWC
    (Master Ground Water Consultant)

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    DIY Junior Member symatic's Avatar
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    Thank you for all the details, the more info the better

    I will be wiring at 230 when I get home.

    The vaccum gauge. Does 1 inch equal a foot of depth?

    I think I grasp the concept of dewatering wells from wikipedia. If I removed the manifold and pumped one of the wells, Because they are so close, would that give an accurate depth reading from the other well?

    So in practice it would Be recommended to find well depth by dewatering the area and then stacking points on one suction pipe vs multiple wells.

    Thanks you
    John c.
    Last edited by symatic; 05-26-2011 at 08:26 AM.

  14. #14
    Jack of all trades DonL's Avatar
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    John,

    1 inch HG vacuum = 1.13 feet at Sea level.

    25 feet lift = about 22 inch HG @ sea level. (The most any pump would lift on a good day, without a jet in the well.)

    Have a great day.

    DonL
    Last edited by DonL; 05-26-2011 at 09:23 AM.
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    Porky Cutter,MGWC Porky's Avatar
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    If I removed the manifold and pumped one of the wells, Because they are so close, would that give an accurate depth reading from the other well?
    No, It still would not give you any useful information.
    Dewatering is only for dewatering properties before inground construction. It has no use in your case.
    Porky Cutter, MGWC
    (Master Ground Water Consultant)

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