I was always straining my back when pulling full garbage bags out of brute garbage cans. The solution that a custodian came up with is to drill a hole in the bottom of garbage can to eliminate suction when pulling the bags out. I'm sure it was located just high enough to avoid trouble if you had a leaking bag. I found this with other ideas when searching Ergonomics.

build portable steps or hook on step that hooks onto lip of dumbster so bags can be dropped in rather then lifted or thrown.

What a great idea, now to drill some holes in those cans at work!

You mentioned if the bag leaks. At the rest area we double bag our trash containers especially out in the parking lots. We only pull the inside bag with the trash unless it's leaking or breaks then we pull them both. It saves a lot of time and messy clean up.