Electro seismic testing for water sources.

[fastline12]

This is a bit outside our area of work and experience but we are exploring this technology simply to learn about it and to test a large site that we own.

I am curious if anyone here is experienced with this enough to offer help, information, or reference links so we can absorb this stuff? It seems that what is common is the creation of a dipole antenna by way of installing two electrodes in the ground and thumping the ground either with a large weight or pyro charge which will excite any water below the surface and that response can be recorded with the antenna. What is still unclear is how to interpret the data received. I realize again this is outside our area but only trying to learn some things on this one.

 

[oldestguy]

There are available out there devices that pound the ground and then sound (not electric energy) is picked u0p by geophones. By movig he geophones farther and farther away and plotting the time it takes

 

[oldestguy]

Ain't it fun when hitting the wrong key the message gets sent in??

To continue
There are available out there devices that pound the ground and then sound (not electric energy) is picked u0p by geophones and a timer measures how long it took to go from imp0act to geophone.. By moving the geophones farther and farther away and plotting the time it takes, differing subsoil, water and rock conditions can be evaluated, with approximate depth at the discontinuity thus determined. A geophone is a microphone of sorts to read ground shocks and sounds that travel through the ground.

The term "seismograph" usually is applied to the devices. Somewhat similar investigation is use of electric voltages applied to two spaced electrodes and measuring the in-grounnd voltage on two other probes. Using both in the same site sometimes helps in the interpretation of the data.

Almost any geotechnical engineering testing firm knows about these and may have one to rent.

Companies that may sell them might be found using the search words like "seismic, geologic testing, cross-hole dynamics, resistivity testing".

They usually result in approximate results and it takes practice to figure out exactly what goes on.

 

[cvg]

a couple of methods that you may be referring to. While the equipment and the data collection is quite easy to use, and may be easy to rent, interpretation of the data is generally done by geologists with specialized training in geophysical methods. I would not recommend a novice attempt to do this type of investigation.

Refraction Microtremor (ReMi)

https://spectrum-geophysics.com/refraction_microtremor_methods.html

Seismic Refraction and Reflection

https://spectrum-geophysics.com/seismic_refraction_reflection_methods.html

 

[fastline12]

Thanks for the responses. While we are somewhat involved with electronics and have multiple fun toys like scopes, DAQ and such, I do agree that it seems interesting how the GT folks are interpreting the responses.

It was my understanding that the piezo effect was being utilized in these scans for water and amplifying the responses from the dipole.

I reviewed some graphs from other Geo firms and it does seem a bit ambiguous in how they determine things. It almost looks like the return wave is sinusoidal and they are looking at the amplitude as well as anomalies or variance in the sine wave that would indicate a strata.


We are not really in a position to donate thousands to a firm for this work as we know we will "hit" water anywhere we drill, it is simply a matter of hitting the right formation that will give the water flowrates we want. This is all shallow drilling so I would think any responses seen on scans would be strong. Not like we need to scan at 1000ft.

 

[cvg]

I'm not sure what your plan is, but drilling a dry hole will cost you thousands that you donate to the driller. A hydrogeologist could increase your odds quite a bit and may not need any geophysical methods. Just food for thought.

 

[oldestguy]

Looking for the best place to drill to get the greatest flow rates, if that is even possible, takes a geologic study of one form or another. Depending on your basic geologic area, it may not be possible. You might get some idea of that possibility by getting a copy of what ever geologic maps are available. In the US many State geologist offices have them for sale or maybe even you can look them up on their web site. Attempting to use electronics would appear to be a waste of time, considering that if that were possible and practical, it would have been developed long ago.

The field of hydro-geology has had many studies of varying or other purpose, but (to my knowledge) no successful electronic method has yet to be found to answer your aim.

The old fashoned diviners with their water finding "devices" usually are fakes. I know of only one such guy that appears to be halfway right, but that is finding buried water lines in the City of LaCrosse, WI. He even can predict depth (most such lines all are at a given depth in the area anyhow).

 

[oldestguy]

One more item. Ground pertinent radar appears to work to depths of maybe 10 feet, usually to detect large voids or a buried item such as a car. It takes a lot more gear than di-poles and RF transmitters.

 

[miningman]

I had to perform a vaguely similar exercise a few years ago , with a similar lack of familiarity with the technology and geology. Ended up talking to a very helpfull government employee ... Dept of Hydrogeology or something who then suggested talking to some local water well drillers. These guys keep excellent records and can advise likely depths of different aquifers without any actual testing.... they just extrapolate data from known locations.