Underground Cable Tracing.

This week I was working in the middle of the Somerset Levels, a mystical place, and was in a cupboard under the stairs when I heard a little girl ask who was in the cupboard, Harry Potter replied her Grandad, a moment later she was stood in the hallway outside of the door and looking me in the eyes as I was on my knees enquired if I am indeed Harry Potter. I neither confirmed or denied being that person ?‍♀

Sparkingchip: 
 

The whole thing sounds like an exercise in trying to prove a point that not many people would even consider trying to prove in the first place.

No no no!!!

A bunch of people made a claim - that they could detect running water underground by dowsing. This is a common claim made by dowsers. Someone else devised an experiment to test this claim, and several dowsers agreed to participate. All those dowsers seemed to agree that it was an important-enough point to devote a day of their life to it.

If instead the dowsers had claimed to be able to detect still water, then an experiment would have been carried out with still water in the pipes. If they had claimed to be able to detect pipes (metallic, plastic or whatever) then pipes of that sort would have been buried, and no water would have been involved. Etc. The test was driven by what the dowsers claimed to be able to do. It was a good test of the claimed ability.

Sparkingchip: 
 

@wallywombat it is accepted that when using a cat and genny to survey a site a third of the possible targets may not be detected, such as plastic pipes.

I do not believe that in the experiment that you referred to with plastic pipes buried in a pit that there is any totally reliable means of detection from above ground without actually digging holes to find out; and in reality dowsing with rods is probably gives the only chance of detecting some buried utilities, how and why I cannot explain, but if it works don’t knock it.

 

That is a bit hit and miss, as the video says that about a third of utilities can NOT be detected using the Cat and Genny. I don't like those odds at all.

Also, why do you need to wear a safety hat in an open field away from all buildings?

Z.

That is a bit hit and miss, as the video says that about a third of utilities can NOT be detected using the Cat and Genny. I don't like those odds at all.

Presumably the likes of gas and water in plastic pipes (without a metallic marker tape) - which won't have much of an electromagnetic influence. Cables in steel conduit should be much easier to detect.

Also, why do you need to wear a safety hat in an open field away from all buildings?

Ah but they're archeologists - there's probably Tony Robinson's helicoper or drone to wory about, or spoil being flung all over the place by JCBs, or camera crews swinging all sorts of things around on long poles, or dodgy experiments with iron age technology done by people with no idea of common sense mechanics or range rovers driven by people not quite looking where they're going  (or maybe I've been watching too much time team…)

   - Andy.

Many ways, with varying efficacy in different substrates and varying rate of fall off with depth. 

Do you have an idea of depth, and how accurately do you need to know the route ?

Electrical,

Make the tube alive with a few volts of a high frequency you can hear on the radio - the genny/cat method is essentially that.

A metal detector, which is a combined low frequency  transmitter and receiver, a GPR has the same function but at higher frequency, so the wavelength allows some phasing.

ELF or DC - energise as an earth electrode and plot the surface voltage contours.

Thermal - blow warm or very cold air through the pipe and image with IR camera. (freezer spray can be injected into the loose jackets of network cables for the same purpose in an emergancy) 

Only good near the surface.

Acoustic - blow gas or play sound into the conduit, or get a colleague to hammer and follow with an ear trumpet, much like the water board used to trace leaks. Works best far away from the origin.

magnetic anomoly - compass may or may not work, a proton precession magnetometer certainly will, but building one is probably more effort than laying another cable.

Probably more ways than this.

Mike

wallywombat: 
A bunch of people made a claim - that they could detect running water underground by dowsing. This is a common claim made by dowsers. Someone else devised an experiment to test this claim, and several dowsers agreed to participate. All those dowsers seemed to agree that it was an important-enough point to devote a day of their life to it.

I don't suppose that they were being entirely altruistic - what they wanted was orthodox scientific proof that their technique works.

Lengthening the thread drift, concerning climate change, we know that it is happening. What we cannot test is what would happen to one half of the world if they stopped emitting, and what would happen to the other half if they carried on.

If the world (including China and USA) stopped emitting in 2030 and the climate continued to change, perhaps we might feel stupid? But the climate change activists would explain it as having gone past the “tipping point”. And then of course the doom-mongers will say that we cannot afford to get it wrong, so we must stop emitting just in case.

Without wanting to be drawn off into climate change too much, if anthropogenic CO2 behaves as expected, then even if the whole world stopped burning fossil fuels tomorrow morning, the world would continue warming for many years until it reached a new equilibrium (even in the absence of tipping points).

Barry knows how to trace plastic water pipes, just like those old water board inspectors.

Ah but they're archeologists - there's probably Tony Robinson's helicoper or drone to wory about, or spoil being flung all over the place by JCBs, or camera crews swinging all sorts of things around on long poles, or dodgy experiments with iron age technology done by people with no idea of common sense mechanics or range rovers driven by people not quite looking where they're going  (or maybe I've been watching too much time team…)

   - Andy.

Yeh but the guy in the video is on his own in the middle of a deserted field.

Z.

Yeh but the guy in the video is on his own in the middle of a deserted field.

Can't be - there must be at least one other person to operate the video camera. Likewise we have no idea what's lurking just out of sight - just because it's not in shot, doesn't mean it can't exist.

   - Andy.