To rapidly detoxify wastes by aerobic decomposition and to discharge the toxicants in the wastes in an early period with sprinkling equipment applied to a final landfill disposal plant of the wastes.

The wastes are virtually divided to three steps of deposition layers 3a, 3b and 3c one above the other and 4 to 8 pieces of sub-piping 5 are horizontally installed at equal intervals to the top surfaces of the respective deposition layers 3a, 3b and 3c. A plurality of spouts are formed at equal intervals to respective pieces of the sub-piping 5 in the form of communicating their inside and outside. Main piping 6 is connected to these pieces of the sub- piping 5. When air is supplied to the main piping 6, this air spouts from the spouts of the respective pieces of the sub-piping 5 and is uniformly diffused to the entire part of the wastes, by which the aerobic decomposition of the wastes is promoted. If cleaning water is supplied to the main piping 6, the cleaning water spouts from the respective spouts of the respective pieces of the sub-piping 5 and is uniformly diffused to the entire part of the wastes, by which the flushing capacity of the wastes 3 is enhanced.