> Horizontal directional drilling costs $10 to $30 (USD) per linear foot with upfront fixed costs of $30K or so.
Underground power lines are expensive, but not that expensive. As far as I know, you dig a ditch, put the power line into it, and then put the material back in over the top.
To pass under roads, under rivers, avoid digging up tarmac, houses, orchards, crops, things on the surface, etc.
Trenching is straightforward, I mention horizontal directional drilling as that puts a cap on the total cost of going underground Vs pylons and above ground stringing.
