Garbage Truck making a wrong turn on to a oneway street

I watched this garbage truck make a left turn on Argyle St. This is a one way street. It was weird because he did have his right hand signal going and then just made the left turn. At first I thought they were going to back up to load up garbage from a restaurant, but they never did. A few short moments later, I saw a similar truck drive by on Barrington St.
Now there could have been an obstruction that I couldn't see, but I would not have chosen to go down a one way street.
The time is off by an hour. This happened at 7 o'clock hour and not 8.