City right-of-way: permit needed for one porta potty on the street?

I'm doing a kitchen and bath renovation on my house in Phoenix. The job will take about three weeks with a crew of four. My driveway is full of materials, so the only spot for a portable toilet is on the street in front of my house. It's a standard asphalt surface, level, and a vacuum truck could pull right up to it. I want to rent one standard portable toilet. Do I need a permit from the city to place a unit in the public right-of-way? Who issues that permit, public works or the transportation department?