Tamalpais Union High School District’s unionized non-teaching staff planned to make a public appeal to the district’s board of trustees Wednesday night after 20 months of labor negotiations have deadlocked. The labor dispute involves 151 employees of the district—which serves students from Stinson Beach to the San Geronimo Valley—including secretaries, groundskeepers and clerks, whose salary schedules are locked at rates set by a contract that expired in July 2011.

District administrators have asked the employees’ union to increase by five years the age at which staff can retire and receive paid health benefits in exchange for a 2 percent salary increase this year and no guarantees for future years.

But union representatives see the deal as an inequitable because they say the concession on retirement age comes with a smaller salary increase than was offered to teachers and management. They have proposed a 2 percent increase

retroactive to 2011 and that retirement age be increased to 60 only for people hired after 2012. District officials say the union proposal would add a cost to the budget of $962,000, whereas their proposal would add $372,000.

Both parties failed to resolve the dispute after seven meetings between negotiators in eight months that ended in October, when state mediators stepped in. The state’s impasse-resolution process could go to the final step next month, which involves an impartial three-person panel reviewing arguments and issuing non-binding recommendations for a settlement.

Officials expect that a report will be issued before the end of the current school year. The district could still impose its offer on employees, but it has said it will not do so because employees could also still choose to strike, an option that is not currently being considered.

Both sides agree on little except that the motives of their opponents are in doubt and the labor situation is as bad as they have ever seen it.

“I can’t morally agree to something that people came into this district and signed a contract thinking they were going to get,” said Laura Ibanez, chapter president for the California School Employees Association and a 13-year employee of the district who serves as secretary for the director of maintenance and operations. “If I don’t stand up and do this now, this will be a turn.”

John Wright, the board president, said the district’s offer to employees amounts to a “very generous” compensation package “by any objective measure.” While salaries may not be increasing as much as employees would like, he said the benefits make up for that.

But the district is also preparing for growing enrollments and needs to be prudent with taxpayer money. “We can’t just give everything away,” he said. “Most people looking from the outside would be surprised that the union is holding out over something like this.”

With talks stalled, staff have turned to teachers and the public for support. A change.org petition supporting the cause has received 505 signatures, and staff have prepared a slideshow touting the value of employees who say their work keeps schools clean, safe and running smoothly.

The union wants to present the slideshow at Wednesday’s meeting, and have planned to speak during the public comment segment.

Mr. Wright said the board understands the value of these employees and that the meeting is not an appropriate place to discuss the impasse. “Negotiations are not something that get conducted in open session,” he said.