Manhole Question

[Hammering]

I'm a builder and have been asked by a potential client what this is. He wants to build an extension but there's a manhole cover in the middle of his lawn quite close to where we'd dig the foundation. This is what's underneath the cover. It's about 30 feet deep, possibly more. The house is fairly new so he can ask the house builder tomorrow but I thought I'd see if anyone on here could shed any light and impress him with my knowledge!

Untitled

• Hammering
• 13 May 2015
• 1

Untitled

• Hammering
• 13 May 2015
• 1

 

[HERTS P&D]

My guess is that it is for storm water and the blue pipe is an access tube to put down a jetter hose.

Andy

 

[PrenticeBoyofDerry]

What did cover look like, as it looks like a vented sewer.

 

[Hammering]

It's a heavy iron cover with just the name of the cover company on it www.clarkdrain.com nothing to indicate an authority or utility.

 

[Nige F]

Now that I'm a gardener I'd like one in my garden - all that free water for my plants

 

[noseall]

30 feet deep!
Are you sure?

That would make an extension close to that drain almost impossible. The excavation work for a system that deep would mean a lot of disturbed soil has been put back over a large area as well as the whole proximity to a drain headache.

Tell him to forget extending. Moving house would be simpler.

 

[Hammering]

It's bone dry!

 

[Hammering]

30 feet deep! Are you sure?

Tell him to forget extending. Moving house would be simpler.

It's very deep!

He's only just moved in and the house is only a couple of years old. He may have to reduce the size of the extension, he wants to go out 7.5m on the side.

Another explanation I've had is :-

Probably a soakaway serving several properties. Would comprise a large flask with permeable walls so that surface water is held and then is gradually released into the soil. 30’ deep so that it’s in chalk rather than clay. Blue pipe air vent ??

 

[Hammering]

The building inspector has had a look at it and it is a type of soakaway (see above). It can't be built over and the foundations have to be a certain distance away so they've had to reduce the width of the extension by about a metre.