DC33 represents about 11,000 nonuniformed, mostly blue-collar city workers, divided into 14 locals. Members have been without a new contract or raises since 2009, as have workers from their white-collar counterpart, District Council 47.
DC33 represents a variety of employees at the Parking Authority, including tow-truck drivers, parking enforcement officers, and mechanics.
Though governed by a separate board - a majority of its members are appointed by the governor - the Parking Authority had been following Nutter's lead in contract talks.
The administration told authority officials not to bargain "until the mayor settled the other contracts," according to a filing with the Pennsylvania Labor Relations Board.
In 2012, Teamsters Local 115, which represents Parking Authority employees at Philadelphia International Airport, filed an unfair labor practices charge against the authority for not bargaining a new contract.
In April 2013, a hearing officer agreed with the Teamsters and essentially ordered the authority to begin contract talks.
It is unclear whether that decision led the authority to begin talks with DC33 as well. The authority's executive director, Vince Fenerty, and DC33 president Pete Matthews could not be reached for comment last week.
Mark McDonald, a spokesman for Nutter, said the administration was "assessing the impact of this contract," particularly on payments made annually from on-street parking revenue to the city and School District of Philadelphia.
"We're not in a position to comment until we have a greater understanding on how this contract would impact those funds," McDonald said.
The deal with employees of the parking agency is just the latest turn in the city's bumpy relationship with its unionized workers.
In January, the Nutter administration presented to DC33 a "final offer" calling for 2 percent and 2.5 percent pay raises and sharply reduced pensions. About 6,800 city workers would have been affected by Nutter's offer.
The union countered with a proposal for 3 percent pay raises and no concessions on pensions, work rules, or furloughs.
Two months later, DC33 members were a heavy presence at Nutter's annual budget address, where union protesters shouted down his attempt to deliver his speech.
Since then, Nutter has settled a long-running contract dispute with city firefighters, and he agreed this month to advance $2.5 million to DC47's depleted health-care fund.
Nutter signaled that relations with DC47 were improving while praising union's new president, Frederick Wright, as a "serious and sincere guy." Nutter said he was hopeful a contract could be reached for the 4,000 city workers in that union.
Wright, who unseated former president Cathy Scott in September, faces a rerun of the election on Jan. 7, because Scott contested the results.