Re.glycol
I dont think it would be a good idea to put Glycol down out side of your house or on foot paths,as it is very toxic to animals who lick there paws,and humans if unlucky enough to ingest it.....dont think the council would be to happy either......not sure if it has a use by date ,but i'm sure there would be people only to pleased to buy it from you...it's not cheap stuff.