Neighbours septic tank on my land Scotland

[MaryGM]

Who is liable for maintenance of my neighbours septic tank which has been in situ before 1990 on my land. It’s an ancient brick built tank and has a very rusty metal covering which an animal can & has fallen through it’s in that bad a state of repair.
My neighbour has been informed several years ago to sort out the cover but he is quite a small minded individual and has not done anything.
Does he require a Wayleave imposed on him to make him sort out his cover of his tank or as responsible livestock owners do I need to cover the tank?
thanks in anticipation

[atticus]

The fact that this thing has been in place for so many years makes it impossible to answer your question based solely on on the very limited information you have given.

It would be sensible to put measures in place to protect your livestock.