Hi Ted, thanks very much for a reply, i was worried no-one would help. Unfortunately the supplier is an ordinary agricultural merchants and doesn't know what the sheet is made of! They are trying to get hold of the manufacturers but no luck so far. However I was told by a landscape architect that silage sheet is good as long as its UV stable. What I've got is black in colour and quite thick, say about 0.7mm. Its not shown any signs of cracking while its been stored for the last 8 months. I spoke to another bloke that supplies various linings for slurry pits and reservoirs and he said if its polypropelene it will be fine and even if its PVC it will be okay especially if its covered over with another layer. I think the butyl pond lining manufacturers don't want people to know there are other options. What is EDPM? How much did it cost and where did you get it?

Matt