Measuring water level in Well

Externet

Joined Nov 29, 2005
1,537
Hi.
Inserting a pex water pipe down the well will be caught everywhere unless it is secured to the wiring or outlet pipe all the way, because it never stays straight.

A few methods:
-Fisk tank vinyl hose secured to the wiring all the way down, and a manometer on surface, like clotheswasher level sensing.

-A pressure sensor by the pump motor and secured wiring to the surface. There is waterproof sensors as ---->http://www.automation.com/images/news/2009/September/honeywell914092_(250_x_200).jpg
Automobiles use them for measuring the manifold pressure, and cheap.

-Measuring motor current on several digits can give a clue of how much water column is there. Pump will work less effort with higher levels.

Has the ongoing drought changed the well reserve level, or is it precaution ?
 

Thread Starter

MikeML

Joined Oct 2, 2009
5,444
Hi.
Inserting a pex water pipe down the well will be caught everywhere unless it is secured to the wiring or outlet pipe all the way, because it never stays straight....
First, thanks to all who have contributed to this thread.

I made a trip to HomeDufus and Lowly's yesterday. I concluded that I would use either 10ft lengths of 3/8" CPVC or 1/2" Gray PVC Electrical Conduit for the standpipe, gluing the 10ft lengths as I push them down the well bore. Both of these pipes are much stiffer than PEX pipe, and are supplied in straight sections, rather than a coil.

I am retrofitting an existing well, and do not want to pull the pump just to install my sounding standpipe.

btw- Google turned up many useful references to "sounding a water well" and "sanitizing a water well".

Due to the caution about pumping airborne contaminates down the well on a continuous basis, I am now tending toward using the air pressure only to initially determine the starting static water level so that I can locate the bottom of the standpipe about 20ft further down. It would be nice to use an electronic means (capacitive/resistive/pressure) that is housed near the bottom of the standpipe but does not require pumping air down it, so that everything can be sanitized right after installation.

I will add to this thread as I make progress on this project.
 
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Externet

Joined Nov 29, 2005
1,537
Take pulling the pump out as a beneficial inspection and maintenance. Will allow doing/securing things right and confidently.
 

inwo

Joined Nov 7, 2013
2,419
Go with the 1/2" pex. Get the first 10' straight. The rest will follow.

Sections will cause trouble.

From someone who has actually done it.
 

Externet

Joined Nov 29, 2005
1,537
Yep. unions/couplings will give trouble. Encouraging to use secured hose.

Well, let's go to non-invasive electronics as another way. And you will have fun building it.
A speaker by the well cap, single pulse or burst. Then the speaker becomes a microphone. The echo delay tells the water surface depth.
 

BR-549

Joined Sep 22, 2013
4,938
Your a serious man, that's a lot of work. It must be a lot tighter than I imagine. It would only take 1/8 " vinyl tubing, it can twist and turn(no kinks) and any length for a bubbler. If you go the stand pipe route, make sure it is air tight. When your pinger fails you, you can try a bubbler. Not that I want your pinger to fail. It's just redundancy. It would be interesting to see the refresh rates thru-out the year, and if they are dropping.
 

Thread Starter

MikeML

Joined Oct 2, 2009
5,444
Go with the 1/2" pex. Get the first 10' straight. The rest will follow.

Sections will cause trouble.

From someone who has actually done it.
How do you couple 10ft of straight PEX to the coiled PEX without using a coupling or the copper bands? That would also put a ridge inside the standpipe, which might cause problems shoving a measurement pod down inside the standpipe.
 

inwo

Joined Nov 7, 2013
2,419
I meant to straighten the first ten feet. Use a heat gun (in Minnesota) to get the first part straight.

Do it all if you can!

But if the first part is good the rest will follow.

Last winter I used a 100ft piece in a 4" cast iron frozen sewer line. It was the only thing I could get through.

Believe me when I say, don't put anything "down hole" that might break off or get stuck. In 5 minutes you can make a weeks work.
 

crutschow

Joined Mar 14, 2008
25,392
.........................
A speaker by the well cap, single pulse or burst. Then the speaker becomes a microphone. The echo delay tells the water surface depth.
That sounds like an interesting approach. One foot of water level change would give about 2ms difference in the echo time. Of course differentiating the water level reflection from other reverberation (echos) could be a challenge.

Is there enough water exposed at the well bottom to make this feasible?
 

Thread Starter

MikeML

Joined Oct 2, 2009
5,444
...
Is there enough water exposed at the well bottom to make this feasible?
Not down the casing because of all of the reflections from the coils of pump cable, but it might work inside a smooth bore standpipe. On my list to check. Seems like everything depends on getting the standpipe in.
 

THE_RB

Joined Feb 11, 2008
5,438
Sonic echo will be almost impossible with such a very thin bore of such a long depth.

Wayneh's idea of measuring pump electrical performance is interesting. Assuming the temperature (winding temperature? bearing/seal temperature?) doesn't affect the results as much as water load, that might be a really good way of solving it.
 

sirch2

Joined Jan 21, 2013
1,026
Assuming you are interested in big changes in aquifer level, rather than a couple of feet, how about measuring the flow rate at the discharge? Presumably as the level drops and the pump has to lift the water further the flow rate goes down.
 

wayneh

Joined Sep 9, 2010
16,399
A flow meter would help. Every pump has a characteristic performance curve of volume versus ∆P. Knowing the outlet pressure and flow rate would allow a pretty good estimation of head pressure.

Back to the sonic idea, wouldn't there be some frequency associated with the air column in the well? I don't know how you'd calibrate it but the resonant frequency in the air column would give a good measure of where the water level is. This would not require bouncing echoes off the water surface. You're just measuring the amount of air.
 

sirch2

Joined Jan 21, 2013
1,026
Nice idea with the resonance of the air column. 300' is a long organ pipe though so the frequency would be very low (around 1Hz if my maths is right) and I wonder if the clutter in the bore would have a greater effect than water level?
 

Thread Starter

MikeML

Joined Oct 2, 2009
5,444
Nice idea with the resonance of the air column. 300' is a long organ pipe though so the frequency would be very low (around 1Hz if my maths is right) and I wonder if the clutter in the bore would have a greater effect than water level?
I am not that interested about how far the well water level drops while the pump is running; I am more interested in the static water level a few minutes after the pump stops, so schemes involving measuring pump performance are not useful...

Since my static level is expected to be ~110ft (33.5m), the closed-end resonances inside the standpipe would occur at 2.52Hz, 7.56Hz, 12.6Hz, etc.

What would be a suitable transducer to drive the air column at such low frequencies?

Could you see the air-column resonances by sweeping the frequency and measuring the impedance of the transducer?

Are resonance schemes easier than trying to measure the time-of-flight of a pulse?

Could a piezo sounder be "clicked" at a rate such that the echo of previous click returns in step with the next click?
 

crutschow

Joined Mar 14, 2008
25,392
In sonar they gate the receiver so it only receives echos at the time expected for the minimum target distance. So you could ping the transmitter transducer and then wait for about 200ms before turning on the receiver. The highest return in that time-frame hopefully would be from the water surface.
 

sirch2

Joined Jan 21, 2013
1,026
The best I've got with a fairly simple free-air ultrasonic distance measurement is about 11m. You will get a lot of echos in the pipe and I suspect picking out the return from the water, rather than the cable, pipe, etc. will be difficult.

Could you shine a Laser down to the water? I suspect not because IIRC you couldn't drop a plumb bob down.
 

Externet

Joined Nov 29, 2005
1,537
Try a tin clicker and listen if the echo is discernible or buried in reverb.
Or hit an iron piece by the mouth of the well and listen, as clickers are not on everyone's parts box.

Discharging a not too large value capacitor (with ~12V) to a speaker to produce a single intense wavefront downwards. An oscilloscope will show if there is a discernible valid echo among the returning signals, and the travel time between the emission spike and significant echoes that make depth sense. (With the help of any microphone amplifier)
 

crutschow

Joined Mar 14, 2008
25,392
The best I've got with a fairly simple free-air ultrasonic distance measurement is about 11m. ..............
But for a lower frequency pulse you could likely detect a longer distance. And the longer wavelength of a lower frequency would give fewer reflections from objects less than a wavelength in size such as the electrical cable.
 
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