[folivier]

For a quick fix you can try this, it will stick to just about anything: http://www.cabelas.com/product/Cabelas-A...id=crrdtfd

This is actually a 3M repair stick that is used to touch up the coating used on pipe that is buried. It is applied with a small torch or heat gun. Just warm up the plastic then melt the green stick so it drops onto the plastic tank.
Or if you can find out what type of plastic and find the same kind you can use it for a patch using heat.

Hey Tom do you think Plast-aid would work on this?