Abstract: In a management system for a water-barrier sheet having a double layer structure with an upper sheet and a lower sheet, the interior space of the water-barrier sheet is hermetically sealed and divided into a plurality of enclosed divisions. A vacuum source introduces vacuum into each enclosed division. Pressure sensors monitor the vacuum condition in the inside of the respective enclosed divisions and a faulty division among them is identified by variation of the vacuum pressure when failure is caused. In response to detection and identification of the faulty division, a repair operation is performed. In case that penetration of water into the ground is not detected, temporary treatment for preventing the water penetration may be made by introducing pressurized air into the faulty division. For permanent repair of the division, water stop material is injected into the faulty division.