Need to run water pipe from remote water well to village 3 miles away

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Old 08-23-13, 05:23 AM
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Need to run water pipe from remote water well to village 3 miles away

I'm working with a remote tribe in the desert of north Ethiopia bringing water to one of their villages. There are two water wells about 1 mile, (well A) and 3 miles (wee B) from the village. I want to run 2" HDME water pipe from the well to a 10,000 liter water tank in the village.
Details of Well A; borehole depth, static water level (SWL), dynamic water level (DWL), and recharge rate (RR) are unknown now.
Well B; borehole depth 195 meters, static water level is 27 meters, DWL and RR are unknown. The government hired a private contractor to drill and develop a borehole, and then failed to install a water pump and storage tank.
I have a solar submersible water pump (Grundfos 11-SQF) with three solar panels (230 watts, 24V each) that will pump 12 gpm. I need to know if this pump is sufficient to push the water 3 miles to the village water tank. If not, what is an alternative.
 
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Old 08-23-13, 10:01 AM
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First and most important is to know the elevations of the wells and the storage tank. Also hills and valley's in between will affect first getting the water there. If the village is at a lower elevation than the wells it will make moving the water much easier (think Roman aqueducts). The pumps will mainly just have to get the water up and out of the well. Once in the pipe gravity will do much of the work and your pump will increase the flow rate. If the village is at a higher elevation than the wells you will have to carefully look at your pump's capabilities since it will have to lift the water uphill and overcome the resistance of 3 miles of pipe.

When looking at the performance charts for your pump make sure you notice the flow rate and at what head. When pumping from a well you may lower it's water level so instead of bringing water up from 27 meters you may pump the well down so you are bringing water up from 100 or 150 meters which dramatically reduces the output and increases the power consumption. Luckily it looks like you are already taking that into consideration with your 690 watts of potential peak output though a 100 meter water depth in the well could put the water beyond your generating/pumping capability.

I don't know Ethiopia but I'm guessing you're about 10 degrees off the equator so at noon you might get 600 watts for a brief period and 500 watts for several hours during the day and less for most of the time. 500 watts limits you to about 1.5 gallons per minute if the water is down 100 meters which leaves you very little left to force water through the pipe since almost all your energy is expended just getting the water up and out of the ground.

The key to all of this is elevation. Getting the water up to the surface is problem #1. Then transporting it 3 miles is problem #2. I assume you are in arid region and because of the well's depth I don't think you will be lucky enough to pump from the static depth for long so you will be pumping from deeper depths. Since your one known well is 195 meters (640 feet) your pump may be down around 600 feet with the water level somewhere above but you really need to figure close to worst case and that is a very long way to lift water and it all comes down to power.
 
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Old 08-24-13, 03:45 PM
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"The key to all of this is elevation."

I cut this out to add emphasis.
 
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Old 08-26-13, 12:22 AM
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Thanks for your advise

Thanks so much for your advise. This area is right at 11 degrees N of the equator and the topography is fairly level. However, I am concerned about "gradual" increases and decreases in elevation that are not noticeable with the naked eye. Is there a way to measure elevation, even approximately?
I'm also concerned about the volume of water that is in the pipeline, 2 or 3 miles of 2" pipe seems like alot of water - before the end of the pipeline and then it needs to be raised 8 to 10 feet.
If I have a high recharge rate (have not tested this yet), perhaps I could raise the pump from 600 feel to 300 or 400 and gain some more pressure at the well head to help push the water in the pipeline. Or, once the pipeline is full of water, I could raise the pump higher to a more shallow level.
Sure do appreciate your help on this Pilot Dane.
 
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Old 08-26-13, 05:35 AM
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The actual depth of the pump is not important. It's the level of the water in the well. The reason I'm concerned is wells are over dug to provide a reserve and 195 meters is quite deep to dig for no reason. If you truly have a good recharge rate you may only have to pump the water up about 27 meters to the surface which would make things much easier.

To do it "properly" you would size the system for a worst case like a dry couple years when the well level drops and you have to use it's full depth. Unfortunately pumping from that depth will be more expensive as you'd probably need a larger pump and more solar cells to power it. And, don't forget that the solar cells will only produce max power for a short period around noon and the rest of the time output will be less with none at night of course so if the system is marginally sized it may only be able to raise water at a slow rate for very short period each day.

I don't know how accurate maps are for your area. See if there are any surveyors or government agencies that can help you determine the elevations of your wells and the village. A surveyor's GPS would quickly tell or a consumer hand held GPS will get you somewhat close.

---
I am glad to hear that you are not going to use children playing on a merry go round to power the well.
 
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Old 08-27-13, 09:21 AM
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Thanks again

Hi Dane,
Thanks again for your response.
I found an altimeter online as an app for my iphone, so I will now be able to check the elevation as well as the GPS coordinates for the water well and the village.
Regarding the borehole, I spoke with the crew supervisor that drilled the borehole and he told me that they used drilling mud for the first 27 meters hit water then rock; so they changed to ram force and broke through rock to 195 meters and opened up a small ocean of water.
I was thinking of setting the pump at about 30 meters and checking the recharge rate before I dig the trench and lay the pipeline.
I spoke with the pump distributor and he said their should not be a problem pumping the water through a 2" pipeline. He is putting together a "pressure switch" system that will turn off the pump when the water reservoir tank is full and the water tank float valve shuts off input - pressure will build in the pipeline and then shut off the pump.
Thanks for your humor about the children. I saw a number of "improvised" water pumps in water pump school, even a bicycle style pump. Amazing how "necessity is the mother of invention." Here in the desert for the last 4 years this has been a key to my planning - be flexible and be creative.
 
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