Anyone know what this is? (Garden manhole / drain)

[Madwife123]

Doing some work in the garden. Found the manhole cover was loose while doing so. It’s a huge wide pipe underneath, no water, can’t work out what it’s for and if we even need to keep it. New build so whatever it is it’s relatively new but it’s not on the plans.

It’s also definitely not watertight!

Ground investigation.
Absolutely not drains or anything structural.
They're normally filled in once they're finished with, but if you're putting a patio over you should be fine.

Emergency fire exit from a hobbit's house?

If it's Cheshire could it be to do with a brine survey ? I am in Cheshire and I remember 30 yrs ago having to pay for one. But ours was just looking at old plans as house over 100 yrs old.

InTheShadow That's mainly the "wich"es, Sandbach, areas north of Crewe etc. So areas like Macclesfield, Chester, Warrington etc aren't included.
OP you can check this on the Brine Compensation Board website but if you're not in mid Cheshire it won't apply.
It would also have been flagged up on your searches when you purchased the house.

Could you have a mole who is motivated by the works of I K Brunel?

Now I'm worried that a little animal will fall down it and die

Seems wide to be a borehole - an SI borehole would be usually 6” diameter not 10” (unless going pretty deep) plus if it does angle away I haven’t met a driller yet that can drill a bendy hole.

If you look at the planning docs they should include the SI with plans of the location of any boreholes or trial pits.

Or it could be pipe dropped into a trial pit for groundwater monitoring, hence the bend.

Isn't it just for drainage in the garden to stop it getting boggy?