Also bins dont really help - my experience is that if there arent any bins responsible owners take the poop home, and the irresponsible either dont pick up, or drop the bags - if there are bins the responsblie owners use them ad the irresponsbile owners still dont if they are more than about 10m away
so unless you have bins every 20m (which would look awful and cost a fortune) theres still going to be poop allover the place and the bins will just be a service to the responsible owner (at a cost of about £200 pa per bin for emptying , plus replacement costs if/when they get vandalised)
IMO as a site manager is that you are better off with a 'stick and flick' policy as at least the poop doesnt get bagged up and biodegrades naturally