Please get me out this literal hole

[Edme]

 

I’m connecting into an existing clay pipe using a plastic 450mm inspection chamber. Everything was going fine until I realised the chamber outlet doesn’t line up with the downstream end of the clay pipe.

 

To explain simply: there’s about a 1cm fall between the two ends of the clay pipe, but the inspection chamber base has a 2cm internal fall. As a result, the outlet of the chamber ends up 1cm lower than the downstream clay pipe, so it won’t connect without going uphill.

 

Do all 450mm chamber bases come with the same built-in fall? Are there any options to resolve this besides digging up metres of the downstream pipe to reach the right invert level?

[Russell griffiths]

Can you not fit 300mm lengths of plastic to the chamber, then go from plastic to clay using a time saver coupling, these are rubber and should easily give you the movement you need. 

[Edme]

Thanks Russell, I knew this must be a common issue 

[Oz07]

I didn't realise 450 ic had as much fall as that. If it were me I'd be connecting it up at both ends then just making the adjustment in the riser pieces or putting it in out of level/ plumb. If the waste flowed between the 2 points before then it will flow again providing its a straight line. Who's bothered if the riser build up is a few mm out of plum you cut the top for the lid anyway.