water well depth

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I have a well on my property. I would like to have a computer monitor
the water depth. There are no sensors or anything in the 825 foot well
hole to measure the depth.

What I was thinking is that the electical power used to move the water
from the top of the well water to my tank varies with distance to the
surface of the water.

Is there any device to measure the 220v AC power used to lift the
water, so that I can deduce at least the relative depth?

Thanks for the help.

Regards, ~Steve



Re: water well depth
snipped-for-privacy@hotmail.com says...
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Yes, a clamp-on ammeter will give you an approximate answer.
Just clamp onto one of the AC legs.
If you have a pressure tank, this won't be accurate, as the head will
increase as the tank pressurizes.

My well guy uses a sonar gauge.  Fairly low-tech, actually; it used a
bullhorn/PA horn driver, and sent out a low frequency "thump", then
measured time until the echo returned.  Requires lifting the well cap,
though.

--Gene




Re: water well depth
On Tue, 25 Jan 2005 23:18:06 -0500, Gene S. Berkowitz

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Right, the responders to this question know the complexity. Yes I have
a pressure tank (rubber bladder inside the tank). It would seem that a
ratio between an easily installed electronically readable (after all
it is in the well house) pressure gauge and some power to pump current
measure would give a relative depth. My water level when drilled to
825 feet filled to about 350 feet. So the force required to lift water
was from 350 feet. I really cannot insert anything into the well,
without messing up the pump.

What I would like is a passive method (from the well top) to get the
relative depth. The idea being if I know that at the start of spring
the depth is x, what is the depth the rest of the year? I suspect this
is a general interest question and some analog guy probably has some
method of determining it. I am not that guy.

Regards ~Steve



Re: water well depth
Hi Steve,

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Ok, since I am an analog guy I now feel prodded for an idea. We don't
have a well, else I probably would have tried something already. Quite
frankly I don't know much about wells either. But the first step I'd try
is echo, as one of the other respondents had mentioned.

This doesn't have to be a huge trumpet requiring lots of space. If you
want to experiment try a small speaker, send a short burst from a
function generator and look for echoes on a scope. Play with the
frequency to see what gives the best echo in your situation. You may
need a preamp that is overdrive proof (diodes etc.) and a filter but
that shouldn't be a big deal. The goal is to isolate the echo so well
that detection is sufficiently secure.

If that works and you want to build something more permanent post again
and we can share more ideas. Basically then you'd have to find a speaker
plus maybe a microphone that won't corrode easily and equip your receive
chain with a 'range gate'. That is a gate which blocks echoes from
unreasonable ranges, for example for the first couple hundred feet and
then past the bottom of your well, to prevent multiple path returns from
being detected.

All this is very similar to ultrasound equipment.

Regards, Joerg

http://www.analogconsultants.com

Re: water well depth
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When the pump is not running, does the water in the line recede to the
level in the well, or does the line stay primed?

Could you simply time how long it takes for the water to reach the tank
when the pump is engaged?  If it takes the pump N seconds to deliver
water to the surface, then referencing N against a scale (either
calculated or benchmarked at different levels) would tell the rough depth.

If the water in the line drops when the pump is off, and if the air in
the line is easily evacuated by the pump when it engages, then the tank
bladder would not apply any back-pressure until the water reaches the
tank.  So, the level of the tank would not be a factor.

 From the proposed sonar solutions, it sounds like the line recedes to
water level when idle, so maybe this scheme could work?

Re: water well depth

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Typical installation of submersible pumps includes a checkvalve at the
pump.  The entire feed line from the pump to the tank remains full of
water and pressurized at the tank pressure.  As soon as the pump
starts, the water begins to flow immediately.  There is to time lag to
measure.


-Robert Scott
 Ypsilanti, Michigan
(Reply through this forum, not by direct e-mail to me, as automatic reply
address is fake.)

Re: water well depth
says...
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How about something  similar to a time-domain reflectometer?  You use a
solenoid to tap the pipe supporting the pump and listen for echoes.
You should get an echo at the point where the water in the well
changes the acoustic impedance of the pipe.  The speed of
sound in steel is about 4500m/second.  If you can detect echoes
with  250 microsecond resolution, that would give you about 1-meter
resolution in depth.  The pump itself should give you another
(and stronger).  That echo could be used for auto calibration
if you know the length of pipe to the pump.

Detecting the echo might be an interesting DSP project--you could
capture a representation of the outgoing pulse, and use auto-correlation
to detect the return.  A bit of research on sonar and ultrasound systems
seems in order.

Mark Borgerson



Re: water well depth
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That sounds like the best idea yet, provided the delivery pipe is
continuous and regular, and doesn't cause too many losses so that
you can't hear the reflections.  Those pipes are usually plastic,
with long lengths coupled, and those couplers might foul the
scheme.

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Re: water well depth
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If you have a means of placing a virtual electrode at the water
surface, you might be able to measure the ohmic resistance from
there to the pump, and thence the ohmic resistance from the pump to
the wellhead.  To do this you need a conductor down to the water
surface, which might be a steel casing.  I would assume from the
pump up is a plastic pipe, which can insulate from the surrounding
water.  Of course the water conductance depends on the impurities,
which may or may not be constant.

If you can get an ohmic reading between the casing at the surface,
and the returning column of water, and my insulation assumptions
are right, that should be some sort of calibratable value.  Maybe.

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Re: water well depth
One way might be to drop a water-pressure gauge to the bottom of the
well. The weight of the column of water on top of the gauge can be used
to calculate the height of the column.


CBFalconer wrote:
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Re: water well depth

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Or if the pump is located at the top of the well, mount a pressure
sensor to measure the suction. This would be inverse proportional to the
water level.

Tom
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Re: water well depth

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I don't think you can put the pump there with an 825' well with water
300 odd feet down. The pump is holding up 10 atmospheres or so (I assume
the pump floats on the water, rather than pumps from the bottom all the
time). A tough pressure gauge down there might help. Otherwise an
automated stone dropper and ear.

Paul Burke

Re: water well depth
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His well is 825 feet deep. You cannot suck water up to more than the
airpressure's worth of water column, which is 10 meters or 33 feet. So there
is no pump at the top.....

Meindert



Re: water well depth


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While I suspect there is SOME limit, it is quite possible to have the
pump at the top of a well that is deeper than 33ft. Check out "jet
pumps" for details. Basically, a jet pump uses two lines to pump the
water in a loop, at the bottom of the loop, is a venturi. The "low
pressure in the venturi sucks more water into the system. Neat trick. I
used one of these for years.

Re: water well depth
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Suction pumps fail slightly before the 800 odd foot depth
specified.  I think the OP specified no in-well sensors were
available.

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Re: water well depth
While I agree that the OP said no "in well" sensors were allowed, I just
thought of another clever way to measure the column of water.

Consider a tube running down to near the bottom of the well, with the
bottom of the tube open to the water. Now, slowly introduce compressed
air into the hose. The air will displace the water until the air starts
bubbling out of the bottom of the hose. The air pressure (PSI) will then
become constant. That terminal air pressure will correlate to the depth
of the water column that was forced out. No? (i.e. it easy to blow
bubbles in your glass of water, but harder to blow bubbles at the bottom
of an 800foot well)

Sure, you'd have to make some adjustments for the "weight" of the air,
etc, but considering the relative densities of water and air, I suspect
these could be ignored.

  - jim

CBFalconer wrote:
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Re: water well depth

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Bubblers are a well-established depth measurement technology that has
been used for years.  The trouble with a retrofit situation is that it
is hard to get the darned tube down there, past the "pit-less adapter"
(any well-buffs out there know that term?)

Personally, I like the echo method.  If it is done right, it can
siphon power from the AC line during pump operations, and then used
the stored energy (maybe in a supercap?) when the pump turns off (so
that things are quiet).  The results could be sent back along the AC
line using one of the low-bandwidth data-over-power-line technologies.
Gee, if it weren't so darned cold here in Michigan I would be tempted
to go out and try some experiments on my well right now :-)


-Robert Scott
 Ypsilanti, Michigan
(Reply through this forum, not by direct e-mail to me, as automatic reply
address is fake.)

Re: water well depth
On Thu, 27 Jan 2005 08:56:33 -0800, Steve Calfee

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I have used a cheap method on my well.  I lower a plumb bob on a cord
and listen for the point where I can spash it on the surface of the
water.  Then I mark the point on the cord and haul it up and measure
the length of cord from the plumb bob to the mark on the cord.  Very
low tech.  Also it doesn't address the dynamic issue of level
depression during pumping.  But it does tell you if the overall static
water table is dropping.


-Robert Scott
 Ypsilanti, Michigan
(Reply through this forum, not by direct e-mail to me, as automatic reply
address is fake.)

Re: water well depth
Damn, I thought I'd had an original thought... Well, there's always
tomorrow.

Robert Scott wrote:
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address is fake.)

Re: water well depth


past the "pit-less adapter"
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It's "pittless". I don't know the origin/etymology of the term

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