NickW wrote:

I am running oil pipes under a gravel drive where people walk and cars
drive. I was going to put the copper pipe inside some spare MDPE mains
water pipe I've got so it should be well protected.

How shallow a trench could I get away with?

It's not (just) that I'm lazy, I'm also trying to avoid damaging some
propane lines which also run through the same ground. I will have to
cross them at some point. Hopefully they will be buried quite deep.



Mine go down about 8 inches. But don't get a lot of traffic. The secret
is to use sand or fine pea shingle in teh trench to spread the load
evenly to avoid crushing. Then top up with MOT type 1, and then your
surface layer.

If you are going to take 30 ton lorries over the top on a regular basis,
I'd go deeper, maybe 15", or fill the trench with concrete, or arrange
some sort of lintel over the top.

The basic thing is to reduce the local tons-per-square-inch by spreading
the load out. MOT type one does this, but needs to be deep to spread the
load wide.

My builder had the bright idea of running them in scaffold tubes. Kinked
the pipe and fractured it drawing it through. Had to dig it all up
again. However, if you have a brain slightly more advanced than the
average Gibbon, it could be a thought.





Cheers

Nick.