Does anyone know much about green waste laws in Ireland?

The reason why I am asking is that my parents got a letter from their county council (undated) stating that some one from their household has been reported by neighbours and videotaped dumping a few hedge clippings and grass in a field in a residential area and that they have been issued a Final Warning (their first letter!) or face a fine...the usual. It's only a few hedge clippings and grass..surely that's not proper waste? Ye all know the sizes of gardens in residential areas mostly comprised of council houses. When did this become an environmental concern? The field in question has been used yearly for bonfires, has broken glass bottles thrown about it, and also has a horse tied up to a pole in it for half a year...yet nothing is ever done about those! My parents are so upset that someone has done this to them, and we just got word that another neighbour got the same letter for the same offense too. Grass and hedge clippings...I just don't see the harm...