I have a number of stray cats that 'live' outside my house. I do not feed them, but they keep coming back. The smell becomes horrible at times and when it rains it really brings out the odor. I do not want to harm them. smell is awful. In the summer i periodically disinfect and scrub the cement, but it is not as easy in the winter.
There is a garden plant called Coleus Canina that cats dislike.So I suggest you put a few of these in pots around the area you mention.They also dislike the smell of Orange so you could use a cleaning product scented with orange to deter them.
Eng Teach
I get sodium hypochlorite from the farm supplies for the concrete. Granted, this may be a bit difficult if you live in the city, but maybe someone could help. It's apparently what farms use to clean the milking parlors. Wet the concrete, dilute the solution, sprinkle on, leave about 15 mins then hose off. Magic!
Is this any use?
What about jays fluid, diluted of course.That should get rid of the smell and I know my cats don"t like the smell when I do my grates out.So it might keep them away for a time.Good Luck.g.