Any drainage experts?

[Mojooo]

(re my other thread, luckily i didn't hire a hydraulic breaker or I could be somewhere in the drainage system right now!)

I am doing a new patio. there ground had 2 components, concrete slabs and then just normal concrete.



The concrete paving was basically where all the slughy mud and bit of wood is:
http://img190.imageshack.us/i/img0642m.jpg/

you can note the drain to the right which has paintbrushes in water (and it covered up at the moment).

to the left of the picture we have an outdoor toilet - which i guess links to the drain

problem is, as i was cleaning away the mud, i noticed a small hole in the ground (and the smell) and it seems that i can kind of see through into the drainage.

http://img190.imageshack.us/i/img0651m.jpg/

the bigger issue seems to be that there is very little between the drain now and the floor - i.e i could probably easily bash my way into the drain!

the other issue is that i need to big deeper to get the right level for my patio AND the concrete next to it needs to be bashed away

i have someone coming but does anyone know what the crack is here? surely the drainage is carried insomesort of metal pipe? could i just bash in the floor and fill it in (once checked by a pro of course).

I am a bit worried about how thin the layer of floor that is left is.

i haven't tried messing about with any other part to the left of the hole but i imagien its equally as thin

any thoughts?

the gallery of pics is here:
http://img190.imageshack.us/gal.php?g=img0642m.jpg

Edited by Mojooo on Tuesday 4th August 20:43

Edited by Mojooo on Tuesday 4th August 20:44

[eps]

?? It might have helped if you'd posted the photos in question inline..

You need to be clear about what is rain water drainage and what is soiled water drainage..

Rainwater _should_ go to a soakaway at least (current regs) 5m away from your foundations..

Soiled water should be taken away to the main drain..

[netherfield]

Either type of drain could be in clay or plastic pipe.

[Mojooo]

just find it odd that the ground is hollow there - i am hoping the rest of the ground around it is solid and that i will be able to fill it in - something can be put there to make it ok to put a new patio on.

i pose i know why they paved over that bit rather than conreting it liek the rest of the patio area

[Gingerbread Man]

Not very sure from the pictures! Have you broken into the clay soil pipe from the outside toilet? Pour water down the outside toilet and see if it runs along the exposed bit of pipe that you have.

If you have no need for the outside toilet any more, this pipe could be removed and blocked up where it tees into the main drainage. Follow it along and see where it ends up.

[Mojooo]

I dont think it is a clay pipe.. as it would be very big for a toilet pipe (the hole seems to go down at least a foot.

or if it was a clay pipe it would be weird if they had just put an inch of mud on top and then paved it?

[Gingerbread Man]

Mojooo said:

I dont think it is a clay pipe.. as it would be very big for a toilet pipe (the hole seems to go down at least a foot.

or if it was a clay pipe it would be weird if they had just put an inch of mud on top and then paved it?

I bet it's been there a long time and over the years an owner of the house has laid the slabs dry/ on sand to extend the patio?

Chuck some water down the outside toilet anyway to see if you get a lead. If not then try down a nearby drain pipe.

[Mojooo]

will do tomorrow,
thanks

[tenohfive]

eps said:

Rainwater _should_ go to a soakaway at least (current regs) 5m away from your foundations..

Unless theres a seperate surface water line, if I'm not mistaken.

[Mojooo]

we think its a soakaway at work.

can i fill it in with soemsort of porous stone and then pave over?

[plumAJP]

you need to find someone to do a camera survey for you, my local contractor charges about £100 for an hours worth.

you need to be 100% certain what that pipe carries and where it ends up. as if you put stone in there now and lay your patio, in weeks to come and your foul drainage facilities start to gurggle and you have foul water on your patio or coming out of your gullies you will have to take up the patio and remove the stone.

if you ring your local council they should tell you where the nearest main public sewer is and if they are helpfull like me, they would post you the map or email it. form there you could guess if the pipe did travel to the main or not. (the council will not hold any plans of your specific drinage lay out).

how old is the house? if it was built before 1936 then it could change the matter slightly.

[Mojooo]

i think its more like 70's - at a guess.

is there any harm in me making the hole bigger?

i am fairly sure its a soakway now as there is a black gutter type pipe going down into it - i always assumed it went into the main sewer pipe, but apparantly not,