[en] Extraction residues generated from Ningyo-toge minerals are stored at the Yotsugu Depository located in the Environmental Engineering Center, JNC, since 1970. Mineral refining tests at Ningyo-toge has been completed in 1978 and the deposit is being exposed to inflowing rain water. Since the role of the above facility was already finished, the residues should be processed in a way that long-term safety is assured and the area should be recovered and planted as an original state. This report concerns the results of investigation on the amount of inflowing water and examination on the quality of water in the drainage, together with the results of treatment tests for removal of radium in the drainage using chemical precipitation methods such as sodium hypochloride and barium chloride solutions and also resin adsorption methods. (Ohno, S.)