Hi, I have an unsightly storm water drain in lawn and wish to a/ build higher/level with yard & b/ cover with grass.
Not for thousands of litres of water trying to move to the lowest point @Noyade. Water "gradually filtered through" is not an adequate surface drainage solution. That's my main concern here.
I've contacted a local water authority, and they advise that any works, whether an aesthetical covering or otherwise, must be approved by the authority in that location.