With four sets of municipal labor contracts set to expire in 13 days, the Nutter administration is fine-tuning a strike-contingency plan to minimize potential disruptions to trash pickup, health centers, library services and, possibly, the 311 call center.

"We're not doing strike planning because we are expecting a strike," Managing Director Camille Barnett said yesterday. "We're doing strike planning because we need to be ready."

Officials for both sides say they expect the deadline to come and go, and there's no way of telling when a strike might occur.

At the same time, the administration has upped the ante in labor talks, with plans to send legislation to City Council today that would create a two-tier pension system for the 23,000 employees who make up the city workforce. Nearly 20,000 are union workers.

Leaders of at least two of the city unions, AFSCME District Councils 33 and 47, said yesterday that they had been unaware of the legislation, and were opposed to it.

Under the measure, which Mayor Nutter previewed in his budget speech in March, new hires as of July 1 would be enrolled in a pension program that is a hybrid between a defined-contribution plan and a defined-benefit plan. Municipal union workers now participate only in a defined-benefit plan, in which they are guaranteed retirement income.

The change means new hires would have a lower level of guaranteed benefits, although they could increase what they get by putting in more of their own money.

Savings in the short term would be minimal, Finance Director Rob Dubow said. But in 30 years, he said, the new plan could cut city expenses by $500 million.

"This is a financial move to ensure the health of our pension fund," Dubow said.

Council will not vote on the plan today; no vote can occur until fall, since today is Council's final meeting until September. If approved, the pension change would be retroactive to anyone hired as of July 1.

It could not be implemented, though, unless each of the four unions agreed to do so in new contracts - which is likely to make Nutter's pension proposal a major point of contention.

Current deals with each of the unions expire June 30.

In the past, the city and its unions started talks weeks before June 30, but this year little has occurred.

The police union - which, like the firefighters' union, engages in binding arbitration with the city - has made the most progress. Representatives of the city and the union have been in talks for nearly a month. The current schedule extends late into July.

The firefighters are not set to begin arbitration until September.

District Council 33, the largest city union with 9,400 blue-collar members, and District Council 47, which represents white-collar workers, have each met once with city negotiators, with a second meeting with each set for next week.

Still, city and union officials say they expect this year's June 30 deadline to pass - as it did last year - with no strike and union employees continuing to work under existing contract terms.

There's far less certainty about the weeks and months that follow.

"We don't want to strike. It is an inconvenience to the city, to everybody," said Pete Matthews, president of District Council 33, which is running radio ads aimed at making its case to the public.

State law prevents police, firefighters, and correctional officers from striking.

Although the last city strike was in 1986, there have been threatened actions several times since then. In July 2000, Street administration officials successfully staved off strike threats days before the start of the Republican National Convention, which Philadelphia was hosting that year.

No events of that magnitude are scheduled for the next few months, although Philadelphia will host an annual national convention for legislators beginning July 20 that could attract 5,500 people.

"If we had to implement something immediately, we'd be ready," Barnett said, adding that most areas of concern included public safety. Though it is still being improved, the strike contingency plan - which Barnett would not discuss in detail - has been basically complete since June 1.

In another sign of uncertain times, the administration on Tuesday sent city workers an e-mail informing them that vacation plans might be scrapped in the event of a threatened strike. Those potentially affected include 2,831 exempt employees - such as those who work directly for the mayor - and 866 workers not represented by any union. It would largely fall to them to carry on the city's business.

"Please be informed that in the event AFSCME District Council 33 or AFSCME District Council 47 calls for a strike vote, all leave may need to be canceled until further notice," the e-mail said.

To underscore their case to the public, those two unions have organized a rally for 5 p.m. today at John F. Kennedy Plaza.

The message, Matthews said, will be: "We are willing to sit down and negotiate for what we don't have, but we are not going to negotiate concessions."

The mayor's spokesman, Doug Oliver, responded, "Anyone who does not recognize a need to make some sacrifice in this economic environment is clearly missing the boat."

Contact staff writer Marcia Gelbart at 215-854-2338 or mgelbart@phillynews.com.