Well and Pump Questions

Discussion in 'Irrigation' started by SprinklerGuy, Jun 17, 2005.

  1. Need to finish a bid for a guy, my first water well involved installation.

    1 HP pump

    pressure tank was running yesterday at 55 lbs while shower and sink were operating.

    Tank appears to be about 50 gallons

    Appears to be 1 inch coming out of tank, reduced from 1 inch galvy to 3/4 copper for house.

    I need to run 6-8 gallons per minute.

    I need 160 feet of mainline before valves.

    Owner thinks he has 12 gallons per minute from well.


    My thoughts:
    I talked him into letting me tap and install breaker and then testing volume. He will pay for this up front. I explained to him that I haven't installed with well involved ever. He is open to this because 5 other contractors have come out in the last month and have not called him back when he called them to ask them where the bid was. I assume this is because they are not comfortable with the well. I would like to do this job because I like a challenge.

    If I tap the line I thought I would just hook a flow gauge to the 3/4 copper out of the breaker and test it. Will this work?

    He seems to think he doesn't need backflow...I think he should have at least a PVB and maybe an RP. Anyone care to chime in on this?

    Thanks in advance. I also plan to call a well/pump guy in my town and pick his brain, he is a buddy of a buddy.
     
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,034

    Avoid assuming anything on wells. The well might run dry after pumping for awhile. The well water might contain sprinkler-destroying sand. The first you can test for. The second you can protect against.

    In a perfect world, the pump would be selected so that it couldn't run the well dry, and the performance of both the well and the pump in the well would be documented for you to work with. This not being the case, your safest bet is to plumb the water (use one inch copper with a 1 HP pump, just to cover your bases) to the outside, and run extended tests. An hour or more will be well-spent here.

    If the well does run dry, you may have to adopt a watering schedule that allows for the well to 'recover' so you can return to full watering capacity.

    You will not assume any flow rate ahead of time. Once you determine the flow rate at the pressure you want, with the pump running continuously (adjust the pressure switch if need be) you have the flow you will work with.

    For protecting against sand in the water, a strainer is installed. (Like a Vu-Flow or Russco) 100 mesh screens, preferably of stainless steel, will protect downstream components.

    Yes, you do need backflow. A well owner might think that they can do anything if they aren't connected to a public water supply with a water meter. They are wrong. That underground aquifer they are pumping from is as public as any reservoir. It requires the same protection. (and even if that long-established legal point sails by the homeowner, the building codes in every state require the protection of the home's water supply from lawn sprinkler backflow)
     
  3. DanaMac

    DanaMac LawnSite Fanatic
    Posts: 13,156

    What did you find out Tony? Need help on the install if you get it?
     
  4. Good info WetBoots.

    It is 1 inch Galvanized at the very bottom of the pressure tank.....this is a basement install so the water comes in under the slab....but immediately the galvanized tee turns into 3/4 copper. Should I still tap the 3/4 copper and upsize to 1 inch? I cannot get to the galvy tee very easily without removing the pressure tank.

    This is a home with a lot of slope....I plan to install an RP...my plan is to tap the water, run it outside, install just a ball valve...charge him for my time...and start testing.

    I will turn the ball valve on and allow the water to run for 1/2 hour and watch the pressure tank, the well pump, and the flow/pressure gauge. This should help me I think.

    Dana, I haven't done this yet....but after I do, I may need help, but not overpriced help like you! Ha! Ha! Actually the install itself shouldn't be too hard, only 20 rotors and no drip or anything.
     
  5. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,034

    Since I've seen a ½ HP pump that could deliver over 15 gpm, a one HP pump could push over 20 gpm, and that would clearly call for one inch copper, even for a fairly short run. Then again, I've seen one HP pumps deliver less than 5 gpm, on account of the depth of the well. I have also encountered wells that ran like gangbusters for half an hour, but ran dry after another half hour or so of continuous running. (and that is not a joy to learn about, with the sprinkler heads already installed) Wells vary, of course, but it never hurts to be prepared.
     
  6. jerryrwm

    jerryrwm LawnSite Bronze Member
    Posts: 1,274

    We make it a point to contact the well driller directly. He can tell us what the well will do, how deep the pump is, what kind of head we can expect, what the draw down is, what the recovery rate is, what kind of sand the well produces, etc. Well drillers are required by law to keep records of every well they drill. They will also give the owner a copy of the well report, but most don't know where it is, or they are not the original owner and have no idea what I am talking about.

    Check with the driller for the accurate scoop on the well.

    Jerry R
     
  7. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,034

    If you count on the well drillers' reports, I have a bridge I'd like to sell you. One of the runs-dry wells I encountered had a nice official document that claimed twice the actual flow. As for sand content, I would lean in favor of a strainer for every well-water sprinkler system, rather than find out later that it was a necessity. Some of the well sand is really nasty, capable of digging into softer valve rubber, with slow leaks resulting.
     
  8. jerryrwm

    jerryrwm LawnSite Bronze Member
    Posts: 1,274

    Well, maybe up in your neck of the woods the reports are not too accurate, but down here in Texas where water supply is an issue, the well report better be accurate. They are required to do a draw down test that would exceed more than actual maximum usage and run the test for an extended period of time to accurately determine the well capacity. Never had one steer me wrong yet.

    Jerry
     
  9. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,034

    And what dire penalty is enacted on the inaccurate reporter? Anyone thrown in jail? It only takes one bad report anywhere to put the question mark on all of them. I say that personal observation beats anything you have on paper. If the sprinkler system fails to work, I could tell the homeowner that he has a well report that is inaccurate, and to go fight it out with them. Or I could just try some tweaking to ensure the system doesn't run the well dry. (this is where I love Hunter PGP's and their wide range of nozzles)
     
  10. jerryrwm

    jerryrwm LawnSite Bronze Member
    Posts: 1,274

    The penalties - possible fines. Biggest penalty - losing the well driller's license. Those guys guard that with a vengance.

    By running the well dry, you have exceeded the recovery rate of the well. Information that would be available from the well driller's log. Also, from that report that details the static water level, the draw down water level and the depth of the pump, it is easy enough to determine a course of action. One being shorter, multiple run times and smaller nozzles on the heads. Another may be smaller zones. Or it could be that the driller could install one or two more joints of riser pipe and lower the pump below the draw-down level. You could also add a storage tank and pump station.

    But I have never ran a well dry nor seen one run dry from irrigation systems. And yes I have installed a good number of systems fed by wells, and worked on many more. The biggest problem that I see is improper use of the pump volume and pressure. They install the system like they would on a city meter without regard to zone size and end up short-cycling the pump. Many have never heard of a pump start relay and wouldn't know how to install one if they had to. It's an easy sell to a homeowner who has had to replace their pump because it burned up from short-cycling.

    Jerry R
     

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