This is an alternative approach:
If you place a certain type of landfill on existing land or landfill, it will return exactly the existing land as different types of landfill.
F.e. if you place dirt over a sand island, you get back sand landfill for all sand tiles.
Limitation for placing with robots:
If you have robots with cargo size > 1, you can place more than one tile per robot. The robot is not able to carry different types of landfill back. So it returns with the total amount of replaced landfill, but as single landfill type (the first type found in list of replaced land)
This is an alternative approach: If you place a certain type of landfill on existing land or landfill, it will return exactly the existing land as different types of landfill. F.e. if you place dirt over a sand island, you get back sand landfill for all sand tiles. Limitation for placing with robots: If you have robots with cargo size > 1, you can place more than one tile per robot. The robot is not able to carry different types of landfill back. So it returns with the total amount of replaced landfill, but as single landfill type (the first type found in list of replaced land)