Can replacement water pipe go above 750mm if stuff in the way?

[ChrisKingston]

Got a long run of lead pipe going from water meter on pavement outside house to kitchen at the rear. Have dug most of a trench for a new plastic pipe:

But there is a big drain pipe blocking access to the water meter at normal water pipe depth of 750mm (marked 2 on this pic, also showing Water Meter, with a 450mm deep gas pipe marked 1 and existing 400mm deep lead water main marked 3):

Regs say water pipe should be 750-1300mm deep and 270mm away from other services (although is that just if along whole trench?).

Only way to do all these things would be to dig right down under the old clay drain (which looks like it has some concrete round it too) and they'd have to sink the water meter connection another three feet too.

Planning to use 25mm or 32mm barrier pipe (plumber suggested barrier not mdpe to save soil analysis) for the new pipe.

Was planning to get water supplier to make the new connection to meter as they do it for free. But they won't give technical advice for free job like this before an inspection (so they can charge for a second inspection?). What is right/normal thing to do in this situation?

1) Insulate pipe at depth lower than 750mm for start of run? Which insulation would that be?

2) Dig new pipe right under the drain to get 270mm under it (still less than 1300 just)? This would be a real pain and would surely weaken the old drain, but only way I can see we comply with regs completely.

3) Dig a new trench to find a route with no other services? Don't think this works as there are loads of services all along front of house, and that drain bends round to go parallel 5o house by look of it.

We only have one approved plumber near us and he was a good guy but said he'd charge 3-4k for job, which we don't have. But kid is due any day now so trying to get rid of the lead before he arrives!

 

[cjcoffin]

I had a similar situation. Cambridge Water inspector said if we were getting in a contractor he would make them dig to 600mm but as it was DIY he would only insist on 400mm.

So if the route above the existing services gives them a good connection path into the meter I think they might be happy enough. They will not want to lower the meter chamber on a job they are doing for nothing. In your front pathway it is not as though it has to accommodate vehicular traffic over it. But I would put some compliant packing e.g. foam or pipe insulation at the crossing points so the backfill does not impose any point loads particularly on the clay drainpipe.

Also I recall there is a requirement to have the pipe in a duct where it passes under the house foundations with vermin proofing at both ends of the duct. At least that is what I remember doing.