A federal mediation session failed to bring Teamsters Local 25 and Republic Services to an agreement that would end a garbage collection strike affecting more than a dozen Massachusetts towns.

Sanitation workers in Philadelphia could go on strike as soon as Tuesday, stopping regular residential trash pickup in the city.

Striking city workers are joining picket lines outside Philadelphia City Hall, public libraries and other worksites as nearly 10,000 unionized employees walked off the job in search of better pay and benefits.