[eru]

> 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.

Why would you drill?

[defrost]

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.