Abstract: Subterranean cavities which can be filled with water or brine are also used for safely depositing ecologically harmful waste. In order to introduce the waste, which must not come in contact with the water or brine, a liquid which is not miscible with water and is specifically heavier than water or brine is let in below the water or brine, where it forms a layer, and the waste is introduced into this liquid via a pipeline, whereby the waste or the mixtures of waste and binding agents must be specifically heavier than the liquid. The displaced water or brine is upwardly removed.