New connection to drain

[Davey]

Hello,

I need to install a new drain connection in to an existing manhole in the garden some 4m away from the house. This will accommodate the outlet from a washing machine which has been moved into our new utility room extension.

The standpipe will discharge into a rodderable gully which will be connected to the manhole in 110mm underground plastic pipe. The invert of the existing drain is 900mm but BC have confirmed the new drain connection only has to be about 450mm deep and we don't need to add benching as the new drain will only be taking "grey water".

What's the best way to break into the wall of the existing concrete manhole? Is it worth hiring a core drill or could this be stitch drilled?

Is the concrete likely to be reinforced ?

This is the last stage of the extension before the BC hopefully sigh it off so any help would be appreciated.

Thank you

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[noseall]

My experience of pre-formed m/h sections is they are not reinforced.

We would stich drill. If you can put your hands on a core drill then go for it. Could be awkward though, working in the trench.

Make sure you take precautions to catch the debris and prevent any large pieces going down the drain.

Did B.C. not ask for a dropper with a directional bend? Or are they happy for the waste water to splash?

 

[Davey]

Hi Noseall,

Thanks for your response - BC were happy for the waste water to splash into the manhole as it will only be grey water from the washing machine.

I take your point about limited access to use a core drill so I'll probably stitch drill it. I'm just a bit worried about cracking the concrete when I break through

One more question if I may?

Paving Expert recommends making the hole 25mm wider than the o/d of the pipe. Is it necessary to seal this clearance before backfilling? I don't want pea shingle to fall into the manhole and/or smells to escape.

Thanks again for your help!

 

[noseall]

Paving Expert recommends making the hole 25mm wider than the o/d of the pipe. Is it necessary to seal this clearance before backfilling? I don't want pea shingle to fall into the manhole and/or smells to escape.

Use some dryish sharp sand mortar to plug around the pipe to seal it on the outside. You can carefully point the internal side once all the back filling is done.

 

[Davey]

Cheers Noseall - thanks very much for your help!

Looks like I'm going to be busy this weekend