Key Condo built a bear proof shed last summer, as keeping the dumpster itself locked proved to be useless (humans could not figure out how to open and then lock it properly, so bears got in all the time).
The new shed has a roll up garage door, a separate man-door for the humans (bears cannot open it), and two windows for ventilation that are covered with wire mesh. We see evidence of bears attempting to get in, with no luck so far!