Abstract: The present invention provides a flexible multi-layer ground membrane that comprises the following layers that are bonded together: a) at least one layer of a polyolefin, e.g. a high density polyethylene, or a mixture including at least a majority by weight of polyolefin with a density greater than 0.9 g/cm3, e.g. greater than 0.926 g/cm3; b) at least one layer formed of one or more polyamides or a mixture including at least a majority of such polyamide(s); and c) at least one further layer formed of ethylene vinyl alcohol copolymer or a polymer including at least a majority by weight of ethylene vinyl alcohol copolymer, said layer c) optionally lying adjacent to polyamide layer b).