Abstract: A flexible sealing sheet for controllably leakproof separation of the regions present on both sides thereof, especially for the sealing of rubbish dumps, which exhibits, in at least one plane, hollow channels extending essentially in the longitudinal extension of the sheet and separated from one another by channel walls. The hollow channels permit, with the sealing sheet already installed, an inspection with respect to possible leakage. It is furthermore possible, by selective injection of appropriate sealing media into the hollow channels to subsequently repair defective portions of the sealing sheets.