In order to empty the trash or recycling collected, a truck comes by that picks up each unit, including the underground container, one by one using a crane, moves the container over the open back side of the truck, and then opens the bottom of the container to release the contents into the truck. The whole unit is then put back in place by the crane. The garbage is actually collected underground and not in the section of the units that is visible over ground.

There are Youtube videos of the process if one cares to look for them.