Remediation strategy, capping construction and ongoing monitoring for the mill tailings pond, Ningyo-toge Uranium Mine, Japan

Saito, Hiroshi; Taki, Tomihiro

Ningyo-toge Environmental Engineering Center has been managing the Ningyo-toge Uranium Mine. The Mine is subject to environmental remediation to ensure the radiation protection from the exposure pathways to humans in future, and to prevent occurrence of mining pollution. The Yotsugi Mill Tailings Pond is considered as the highest prioritized facility. So far, capping is put on the stable upstream part of the Pond to reduce dose rate, radon exhalation and rainwater precipitation. Prior to its construction, it was decided that the capping are to be multi-layered and natural materials are to be used, and the capping specifications were decided. Also, drainage channels and gabion work are constructed around the capping and at the foot of capping slope, respectively. Monitoring, which will continue for years, has started to confirm the effectiveness of the capping and the data will be utilized for the future remediation of the downstream of the Pond.