It is not required for someone to be on-site, but it is required for us to have a contact name and phone number in case there are any access issues or placement instructions. If we need to make a secondary trip, you may be charged. That's why it is important to provide very clear placement instructions prior to delivery. For example  "Put dumpster on the North East Side of parking lot closest to the red awning."  Other considerations to make us aware of: Preferred Time Of Day, Gate Code/Access, Space Restrictions, Overhead Branches or Wires, Traffic, Wet Concrete, etc.