Well cannot see your picture, but Thames Water have something as you
describe every few streets and the can use a kind of water pressure meter
that looks a bit like a bollard which plugs in and one supposes has a
cellular connection so they can track blockages or leaks.
They only use them for a while of course, take that from one who has
collided with many in my time of being blind!
Brian

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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Robert" wrote in message
...
In the pavement outside our house is a 200mm square concrete "plug" or
panel in a pavement slab, probably about 50mm thick. Plug is a courser mix
concrete than pavement.
It isnt mortared in and I could probably lift it out if necessary.
What is it likely to cover ?
Old Water stoptap ?
I would like it to be access to the "drain" which exits our Victorian
terraced house 10m away , taking both surface and foul water, and connects
presumably to the main sewer in the road but which has no manholes
anywhere.
Photo: https://ibb.co/cC3dQBp