Need advice with rural water well pump design

Problem: Design a pumping system for this rural water well:
- we have a new 240' water well with 6" PVC casing on some rural ranch land north of Austin, TX - the screen is set from 140' to the bottom, which was plugged at 240' (we hit salt water, so we had to cement back up to 240':-( - good water pushed up to 110' - where it remains - we have not placed any pump in the well as of yet - we have 110 & 230VAC next to the well - the "main problem" is that the well only produces 3 gallons per minute! So we have to design around this problem. Our best guess is that the well will constantly produce 3gpm of good water, but that's the best "rate of flow" that we will ever get.
Here is my first thoughts for a pumping system:
1. Install a high quality small stainless steel submergible pump and a small pressure tank at the well. Not sure which brand of pump, size of pump, etc. The idea is to end up with a high quality submergible pump system that will keep the 3 gpm flowing & last for five or so years.
2. The submergible set-up above will keep a 2,000 gallon poly storage tank filled by use of a float switch(s). An above ground "second" pumping system will deliver a large volume of water as needed to the home, yard, etc. - up to the amount of water available in the 2,000 gallon tank.
What I need is "SPECIFIC" recommendations as to the pump(s), tanks(s), float switch(s), etc. I need make, model, etc. data to design this system. Choosing the proper horsepower(s), etc. of the pumps is a bit fuzzy for me:-)
I am currently looking at the Grainger catalog number 394 (page 2811)and the Grainger site for pumps & switches, etc. Here is the Grainger catalog in PDF: http://www.grainger.com/Grainger/wwg/catalog/viewCatalogPDF.jsp?CatPage(11
THANKS in advance:-) !!!
Gene Briggs, TX
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eMail: snipped-for-privacy@thegateway.net



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You don't need a pressure tank on the well. You will need a pressure tank for the pump on the cistern.
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THANKS,
So just orifice the outlet (from the submergible pump in the well) to where it is impossible to "over-run" the small submergible?
One of my greatest worries is to somehow run the submergible out of water and burn it up. Then we would have to pull the entire 200+ feet of pipe & pump.
Gene

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I'd add a timer to the well pump so that it wouldn't run for 18 hours straight. Set it up on a cycle so it runs for half an hour, rests for an hour to let the well recover, then runs another half hour, etc, until the float switch says the big tank is full. Run and rest times are an arbitrary guess. You'll want to do some testing to find the best intervals to get best results from your well.
Gary
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there are little electrical gizmo boxes, one brand is called pump minder,but basically it's job is to shut down the pump when it gets dry,Ithink it measures amps drawn and sez" who boy, shut 'er down till things cool off and the water level comes backup". they are fully adjustable to amps and time to recycle and switch back on. real pump guys are savy to them
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Not able to help with specifics but I do know the psi tank is for the household sytem (your 2k gal poly tank). Sounds like you want your sub-pump to operate (only) when the poly tank gets low, you don't want it to take more than 2 or 3 gpm (run the pump dry = pump burnout?). At 2 gpm it will take 1000 min of pumping to fill the poly tank, like 16 hr. Lot's to think about. If you don't end up with solid answers here I'd think about hiring a pro... those pumps get spendy and pulling 140' of drop pipe with a pump at the bottom is a bit of work. Good luck!
Rob

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The only reason that I want a 2nd smaller pressure tank is to keep the submergible pump in the well from constantly shutting on & off. The plan for the 2,000+ gallon poly holding tank is to draw down to say, 500 gallons, then the submergible kicks on & fills it up to the 2,000+ limit. This way, the submergible is not constantly switching on & off. I really do not care what the above ground pump does, it's easy to replace & service. It will probably have a ~100 gallon pressure tank and be a 60psi with a large rate of flow.
Gene

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I'd talk to a pro about this... An 'on' switch for the sub pump at 500 or 1000 gal down and an 'off' switch when full. That way the pump will just run until you get enough water.
Rob

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You are forgetting about the water that is stored in the well. Your pump moves that water as the recovery water 'runs' into the well. A 6" well has 1.47 gal/foot of water. With a screened well the pump is usually set at the top of the screening but.... that depends. You really need to know what youre doing with this or you are going to have future problems.
You really don't want to pump 1500 gallons all at once. You want to store water in the cistern, so you should use water and then replace it after say 50-100 gals. Saving start ups of a pump is a good idea but, there has to be a balance in the system and the well is key to all this effort. So you don't want to screw up the well or the water qaulity by over pumping the well by constant large drawdowns. IMO, you need to know the pumping level of the well. That's pumping until the water level stops falling, then you set the pump 10-20' below that level or... you set the pump according to the screening. I'm not very familiar with screened wells but you don't set the pump 10-20' off the bottom as you can/should in a rock bore well.
I suggest a float switch to control the sub pump and a safety float switch to control the house pump so it doesn't run dry. You need to know proper/correct size sub pump for in the well and you don't size it based on the recovery rate of the well. You size it based on the total head into the cistern. Size isn't just hp, it is gpm and then the proper hp to do the job. And that gpm has nothing to do with the recovery rate gpm of the well.
Gary Quality Water Associates
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wrote:

I'm assuming you will set the pump at least a 100' in the water and your driller's recovery estimate is accurate.
My first thought was a 6' Aermotor windmill but it won't lift that far. An 8' would but it might outrun your recovery in a high wind.
Most 1/2 hp submersible pumps will pump 5 gpm. You would have a 2 gpm drawdown. Quick calculation shows about 130 gallons in 100' of the 6" pipe after deducting for the displacement of 1 1/4 " pipe and wire. That is a little over an hour before the pump is out of water.
Being conservative, I would set a timer for 30 minutes on and 60 off. That will give you 2400 gallons per day. It won't back flush Barton Springs but it is 5 times what a normal family uses. You've got the rest figured out.
One other thing you might look at is at www.pumpsandtanks.com Look for Subgard.
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Gene wrote:

240'. The static level is 75'. Sustained flow is about 2 gpm pulled down to 220'. I have a 3500 gallon storage tank on a hill about 40' higher than the top of the well, and 60' higher than my house. I just use gravity feed from the tank to my house (no booster pump) and live with the ~30 psi water. I'm in a very rural area and chose this arrangement so I can get through several days of power outage.
For a top quality pump which will not distroy itself by pumping the well dry I'd recommend one of the Grundfos SQE models. These have a processor in them which measures motor current, voltage, speed and temperature and they have adjustable setpoints to protect the motor. A 1/2 hp pump should be sufficient for the head and flow you've discribed. They make a nominal 5gpm model. Check the Grundfos website for performance specs and how to calculate for your situation. You can use a float switch with a power relay on the power to the pump to keep the tank topped off, or if you like a little fancier setup and more control get the CU100 controller for the pump. With that and a 4-20ma pressure transducer you can monitor the actual tank level, record the cycling of the pump, and set the pump to shut off based on the head the pump has to push. WIth that you'll never run the well dry. Thats the setup i've just put in my well. Mine's a 1 hp 10gpm unit and the whole thing including having a pump company install the pump was around $2000. I did my own wiring, bought the controller seperate and got the transducer on ebay. My old Grundfos stainless pump without all the nifty protection lasted 9 years. I killed it by letting it run dry for three days. Human error ;-(
You can certainly get cheaper pumps, but most of the cost is getting a crew out to remove and install a pump, not the pump itself. Ok, you could do that yourself too....;-) -- Lou Boyd
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