Based in the UK for context.
I recently had my old lead water main replaced. The trench was dug by a contractor but I backfilled this trench and have been building a garden path above (MOT sub base + brick stair risers).
The gas main runs underneath the path, parallel to the water main but on the other side of the path, and shallower (we're talking about a foot depth if that). The contractor who dug the trench for the water pipe also dug out around the gas pipe (they weren't sure which services were where so had to dig a bit to work it out). They filled this bit in and when they were done there was no gas pipe visible as I recall.
Since I started compacting hardcore and MOT sub base above the clay, twice I have noticed a very faint smell of gas right at the bottom of the path, near the pavement (furthest from the house). It's almost undetectable and it's gone as soon as I get the first whiff - almost like it just got carried over in the wind. I can't smell anything by putting my nose to the ground.
My plan at the moment is to call the gas emergency line and get someone round to check for leaks. If it turns out there is a leak, who would be responsible for fixing this, given that:
- The pipe should have been bedded in sand/gravel to support it
- It's the gas main before the meter, I don't think I own this as the home owner?
- The pipe is laid too shallow and is very old / predates building regs
