Help me find my ducts

[jamieled]

The background is that about a year ago, our foundation slab was put in, with two ducts to pull through bt and electrics when the time was right. I didnt see them go in, but I told the groundworkers where to put them. The ends of the ducts were buried.

 

Fast forward a year, I need to get the services in, the ducts are nowhere to be found.

In the first photo below the ducts are shown coming up through the slab. In the second photo, the area where the ducts should be is shown. They should theoretically come out just to the right of the black bucket.

Things I've tried:

 - phoned the groundworkers to jog their memory.

 - Dug a massive trench right round this area.

 - Rammed a water pipe down and tried to see if I can get water to come out into the soil at the other end.

-put a bit of light down the duct to try and find the direction.

 

At the moment I'm a bit nervous about continuing to dig around the pad holding the post up. Anyone got any words of wisdom or ideas?

 

Have a plan b not involving the ducts, but I'd rather avoid that if possible.

 

[ProDave]

Fill the ducts completely with water from the inside.  Wait for a damp patch on the ground to appear outside.

 

Go divining for it (when full of water)  Have you tried divining?

[jamieled]

The water level in the ducts hardly drops when I do that, making me think the end of the duct is crushed or blocked. 

I haven't tried divining, but would happily give anything a shot.

[ProDave]

Give divining a test.  Get two metal rods and form them into a long L shape. (I use two old straightened out bucket handles)

 

Hold the two short bits of the L with the long bits pointing forwards.  Then slowly walk over a known submerged object like your water pipe.  See if the rods move.

 

I didn't believe it until I tried it and it works, but don't ask me how or why.  I am told you can detect almost anything so think about what you are hoping to find.

[ProDave]

Alternatively send a set of drain rods down with nothing on the end and hammer at what they come to a stop at and see if you can get any movement.  Mark how far the rods go in, pull them out and measure, That will give you a good idea where they got to and where to dig.

[Declan52]

Set of sewer rods and a mouse and cat will find it in secs.

https://www.gem-tools.co.uk/cat-radio-detection-mouse/

[AdamSee]

I would suggest feeding a cable down it then use a ground scanner....but Declan52 surgestion is actually a guaranteed way of find it. You only have to feed it a meter or two, find it then follow it as someone else pushes the mouse further.

[Mr Punter]

Cobra duct rod would be better than drain rods as they are slimmer and normally over 100m.  Feed in nicely and don't tend to get stuck.

[Russell griffiths]

On another note mr @jamieled do you have any more pics of that cladding please. 

[jamieled]

Cheers all. Pleased to report some success with some low tech methods. Red Indian style ear to the ground while ramming a rod down the duct.

 

@Russell griffiths of course. Piccies tommorow. We went with a fairly rustic approach  - rough sawn larch heartwood, board on board.

[jamieled]

@Russell griffiths as requested.

You can probably spot the earliest efforts as we learnt quite a bit as we went through it. The lean to turned out quite nice as we were able to use single boards from top to bottom (third photo).

 

Any questions, ask away.