My side driveway is tarmac and something has put mud marks all over it. It looks as if an animal with very muddy paws has trotted down it, but I suspect it is more likely to be the kids with their mopeds, putting them up on their stands and consequently making all these muddy marks (can't prove it). I have tried washing it down with plain water and scrubbing it with washing up liquid but it is still there annoying me. Any suggestions as to what I could use to get rid of it. Tarmac looks nice at first but it has little grooves in it that retain the mud.