OK, here's my fiew on this. In Canada the local code says it's OK to have
the 'wires in the same trench, as long as they're in separate conduits.
So in one trench, I put water line( good 5/8 garden hose),in 4" weeper
conduit,backfilled 6 inshes,then 100A service feed,again in 4" NON weeper
conductor piping,backfilled 6",then another 4" nonweeping conductor in which
I run TV coax and 2 CAT5 cables,backfilled 6 inches with gravel,then good
The CAT5 wires are for phone lines and alarm system.
Sure it's overkill,but the big conduits give me EASY access for 'upgrade' or
repairs and everything is now in the shop IF I want it in the future...