Drainage Adjacent Proposed Extension

[compoxx]

Hi,
I have planning permission for a single storey extension to the rear of the house. The existing drainage has an invert level of 300mm (very shallow). the house is a 1950's bungalow.
The drainage inspection chamber is only 750mm away from the corner of the exisitng bungalow.
Imagine a line from one corner of building where the MH cover is to the opposite diagonal where the corner of the new extension will be. extend this line a bit and thats the current line of the drain.

Question: how close can you be before deciding to move the drain? The drains are vitreus clay so I will renew the section in plastic anyway as fdn excavation will disturb.

If re-route drain not enough depth in the Inspection chamber at end of garden to make the connection at an adequate fall.

Any suggestions??
Sorry for long windedness. Without showing a drawing very diff to explain.

Thanks....

[stoneyboy]

compoxx,
You should be able to discuss this with your LBI and reach an agreement.
end

[holboob]

you can normally build as close as 100mm away

[compoxx]

Thanks Holboob,
I have decided to reroute the drain. Thought it will be better in the long run to divert the drainage alongside the extension rather than running underneath the slab.