| 摘要 |
PROBLEM TO BE SOLVED: To prevent a contaminant and contaminated water staying inside a shielded tank from leaking outside by detecting a damage in an early stage by a method wherein a water level inside a shielded tank and an underground water level outside an underground-confining facility are respectively monitored, and a fluctuation of a water level when a damage is generated in the shielded tank is observed. SOLUTION: An underground-confining facility 11 of a contaminant 14 is equipped with a shielded tank 13 principally composed of a water-shielding sheet 12, the contaminant 14 is stored in the shielded tank 13, and contaminated water 15 of the contaminant 14 comes to be stayed therein. An water level inside the facility observing well 17 is formed in the shielded tank 13, and level sensors 19, 19 are respectively arranged to an upside and a downside of a water surface of the contaminated water therein. Besides, a water level outside the facility observing well 22 is provided in the ground G. Then, in the case where generation of a fluctuation of a water level H1 in the facility exceeding the maximum value of a specific control widthΔH is detected with the level sensor 19 in the water level inside the facility observing well 17 while the underground-confining facility 11 is operated, an alarm device is functioned.
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