When removing a tailings pond the structure is removed and returned to your inventory. However the texture of the structure remains on the ground. You can build new buildings there, but they will be placed over the texture of the tailings pond. When this happens it seems as if the texture of the pond has replaced the texture of the actual floor.
EDIT: this appears to only be the case when the structure is removed by a deconstruction planner (aka have a robot remove it)
