TIVERTON — The School Committee last night mulled a proposed one-year contract that would give the town’s 200 public school teachers 3 percent raises retroactive to last August and add more than $500 to employees’ out-of-pocket expenses for health insurance premiums.

After a closed-door session, School Committee chairwoman Denise deMedeiros said the committee had made no decision on the proposal, which had been put forth by the teachers union.

But at the same time, deMedeiros said the committee will ask the union for a financial package for a second year.

She said the committee’s negotiators, Schools Supt. William J. Rearick and Douglas Fiore, the director of administration and finance, had been negotiating with teachers in the context of a two-year agreement.

The one-year proposal submitted by the union came “out of the blue,” deMedeiros said.

Earlier in the day, union president Amy Mullen said there was agreement at the negotiating table on the first year, but “we are still not close” on the second year.

DeMedeiros said the two sides “were beginning to make headway” on the second year.

Among other things, the union proposed an increase in teachers contributions to health insurance premiums from $1,100 to $1,662 for a family plan.

But deMederios said the committee wanted language that specified a percentage of the cost of premiums — 12 percent in the first year and 18 percent in the second year.

Mullen, meanwhile, said that the School Committee budgeted for a 10 percent increase in health insurance cost, but the actual growth was less than 5 percent.

Fiore said the increase came in at 4.4 percent.

Mullen said the committee nevertheless sought to increase the proportion of teacher contributions to health care because it had under budgeted the cost of running the new Ranger Elementary School and “that money has to come from somewhere.”

Last night, Rearick angrily denied any connection between teacher contributions health insurance and the cost of running the new school.

The savings in health insurance premiums in the current budget has gone to offset a reduction in state aid to education.

He also accused teachers of trying to hold high school seniors “hostage” by saying there will be no senior projects unless a one-year agreement is signed.

The union proposal would provide for a senior projects coordinator, who at a minimum organizes the judging of senior projects, which for the first time are a graduation requirement for the Class of 2008.

Seniors are working on their projects as part of the curriculum in English class, by all accounts.

And Rearick said, “if the union chooses not to participate in that process we will ask the committee to waive the presentation part of it.”

Seniors will fulfill their graduation requirements as long as the senior projects are done, regardless of the judging, Rearick said.

Since the first week of September, teachers have been working under Superior Court order according to the terms of an expired contract — which makes no mention of a senior projects coordinator.

In the past, a high school teacher has volunteered to organize senior projects for those who wanted to go through the exercise. But this year, teachers are withholding extra services.

Mullen said the union’s one-year proposal also would require teachers to serve as advisers to high school students, fulfilling a state requirement that high schools provide a personal experience to their charges.

The high school’s plan for implementing the new graduation requirements has not yet received the approval of the state Department of Education, in part because it has not demonstrated that it has taken steps to personalize education.

gmacris@projo.com