Waste-dump, slag-heap. Waste and slag are not particularly tricky (meaning odpad and troska respectively), so it's dump and heap I want to focus on, and while I'm at it, I'll add the word "tip" as well, as in "refuse tip" /REFjús/, where refuse is waste like garbage, rubbish (Brit.Eng.).

These are further examples of English words which do not change their form, but often change their grammatical usage from noun to verb and back again. What is interesting is that, as verbs, they include the idea of movement, heap suggesting upwards, dump and tip downwards. Heap means putting stuff on top of other stuff to make a final cone shape, like sugar in a spoon. Dump and tip both mean dropping stuff on the ground or into a hole, but dump suggests roughly and heavily, while tip might be more carefully and gradually, like material from the back of a tipper-truck. These words are used in the typical combinations given above, practically like fixed expressions for different forms of waste management.