At L.A. City Hall, it was the most hotly debated policy initiative of 2012: a new law aimed at reining in retirement benefits for thousands of future public employees.

Alarmed by steadily growing pension costs, the City Council voted to scale back the size of pensions offered to each civilian worker hired after July 2013, over the furious objections of organized labor.

Since that vote, nearly 2,200 people — librarians, trash truck drivers and many others — have gotten city jobs that included those reduced benefits. Now, the retirement savings generated over the last two years are about to disappear.

A proposed four-year salary agreement with the Coalition of L.A. City Unions calls for the council to abandon that 2012 pension plan. Those nearly 2,200 workers would revert back to the older, more lucrative retirement benefits that have been in place for decades — and are increasingly viewed as financially unsustainable.