sorry for the odd title. We're working on a project to find a cheaper and safer way to install high voltage power lines in the Scottish highlands. One of my group mates had a really cool idea to instead of actually digging underground, you could just lay the cables and cover them with dirt/some other material which we haven't thought about at the moment.
I am asking because I assume the industry would currently be using the best available technology to them, and they don't use this method; they lay them underground. I'm trying to figure out the potential drawbacks to this proposed method.
1) Initially i thought it could be regulations, i.e. minimum depths etc, however, as far as I can tell from official documentation, there are only guidelines. In general, cables are laid between 0.45m -1m below ground, but not always. For example from a cable map I found, there was an 11kV line just 35mm undeground in Edinburgh. Official documentation seems to imply depths are situational, and as long as a risk assessment is performed, shallower or deeper depths can be allowed.
2) In terms of cost, digging through the rocky terrain of the Scottish highlands would pose significant challenge and cost. Getting heavy vehicles out onto that sort of terrain isn't easy. Using some sort of packing material, such as dirt, would surely be a cheaper option? There would of course be costs incurred due to rough terrain for transport trucks etc, but I don't see how it could cost more than digging through the terrain.
Potential drawbacks I can think of:
1) Using a mound structure would pose issues such as erosion. However, maintenance (which must be carried out on cables anyway) shouldn't be too difficult, especially since faults in the structure would be easy to spot since it is overground. It may require more regular maintenance due to weathering, but that would be offset by the fact that each maintenance trip wouldn't involve unearthing the ground?
2) Potential damage to cables. I don't even know if this is a real drawback (in comparison to the existing system since cable damage isn't very uncommon). I read some case studies from one of the regulatory bodies, and it seems damage came mostly when projects were undertaken without consulting the relevant authorities for cable maps. I assume the mound layout would be very similar, and probably wouldn't encounter a greater frequency of damage to the cables, but this is pure conjecture.
3) It would be an easier target for malicious activity since it would be easier to get to without the need for heavy machinery. However, cable maps aren't very difficult to get, and someone could just as easily target shallow cables using the current system.
Ultimately, does anyone have any criticisms of the potential solution? Or does anyone know of this idea having been implemented but not worked, or was determined to not be feasible? Thank you very much!