Instead of email, write hardcopy/paper letters which are still the way to go in regards to actually getting the attention of the public official you seek. It's far too easy to have one's email buried in a format so readily available these days.
Then also write several letters to the editors for your local newspapers. If you have the time, try conceiving and running a petition (and I don't mean online) then send copies to the city council and mayor.
Be persistent but don't be obsessive compulsive.
Also, write to the chief of police and whatever department is associated with the management of the city truck (sanitation, zoning board, etc...) as well.
If this is a one time incident, don't expect too much to happen over this indiscretion. If it's a recurring set of violations, document the violators thoroughly. Chances are its a departmental disease where poor management is not properly supervising its staff.