Found this when starting digging footings for conservatory.

[EddieJT]

I presume it's the power supply to the house? I'm surprised since this is the back of the house, and electricity meter is on the outside wall of the front of the house.

What's the solution? If I have to, I could just reduce the width of conservatory from 6m to 5.6m to avoid it.

 

[catlad]

I can't tell how thick it is from the photo! could it be your water supply?

 

[EddieJT]

Actually, yes it could be. The stopcock isn't far away on the other side of that wall. I'll go and measure.

 

[EddieJT]

Just got the calipers on it, and its 22mm diameter.

 

[EddieJT]

Can I shutter and lintel it? Would this pass building regs, as I'm in 2 minds whether to do a proper extension which will needs BR, or just a conservatory.

 

[CBW]

I wouldn’t be concealing it if it’s mains water, especially since it doesn’t look laid to the correct depth. Try running water inside and feel the pipe for slight vibration.

 

[JohnD]

is it black polythene? You may find a makers identification embossed or printed along the side.

 

[noseall]

Can I shutter and lintel it? Would this pass building regs

Yes, yes and yes, or...
Dig out your foundation as normal then sleeve it with a split downpipe, then tape it back together with a bung in each end. Don't let the discovery of a service put the job off unless its a gas service. A gas service (yellow or steel) should be moved to an outside wall and not be built over.

Electric and water (sleeved) are ok.

 

[noseall]

it doesn’t look laid to the correct depth

Lol.

 

[Ian H]

I’d be tempted to extend the duct to outside of the extension.