A bit OT now, but if you'd like your worms to come back and do some great work in your garden, keep in mind that worms go where there's food. If the organic food that occurs naturally in your soil is gone, which it would be in a built-up area after many seasons of rain, cleaning, etc., they the worms die off and/or go somewhere else.
If you'd like to bring them back to your garden, here's a great DIY way to do it!
https://deepgreenpermaculture....
I love worms! They're the best!
