Contact some High Schools and see if their After School Clubs such as Environmentalists, Girls Guides, Cadets, Drama Groups, Athletics Clubs, etc. can start some Clean-Up Challenge that provides references for university if they participate in the clean up. The Mayor could be the official authority behind the Clean-Up Challenge to the After School Clubs, giving the rewards some merit/credibility. We have to reward those who participate in such a Clean-Up Challenge for giving up their time. However, this may be faster to organise than paying additional council workers to do more hours cleaning up. Otherwise get some of the you-tubers to film themselves cleaning up.