Two years after voting to unionize, teachers at Olney Charter High School have ratified their first union contract.

The two-year deal guarantees raises totaling 4 percent over the life of the contract, which was struck with Aspira Inc. of Pennsylvania, the school's charter operator.

More than 120 teachers, nurses, counselors, and instructional assistants are covered by the deal, which includes performance-based pay.

"Our contract ensures fair, consistent, and transparent working conditions for all of us at Olney," Ellie Sammons, a veteran Olney teacher, said in a statement. "We all know what we are responsible for, and we all know what kind of supports we can rely on from our administration."

Nathan Cross, an Aspira spokesman, said the organization was "pleased" with the deal.

"Throughout this process, we made it clear that we would negotiate for an agreement that would benefit the students and community we serve," Cross said in a statement. "With this new contract, we believe that goal has been achieved."

Two years ago, the Olney teachers voted to affiliate with the Alliance of Charter School Employees, Local 6056, a part of the American Federation of Teachers Pennsylvania.

Olney is the largest unionized charter in the city, with 1,500 students.

The staff ratified the contract Monday, International Workers' Day.

The pact includes paid maternity and paternity leave, time for planning lessons, and monthly labor-management meetings. It also limits class sizes and governs teacher evaluations, mentoring, and the development of student growth objectives.

"Our contract will allow us to work closely with administration to address labor issues, limit class sizes, trust educators' professional judgment about teaching methods, and ensure that disciplinary matters are handled with dignity and respect," said teacher Sarah Apt, a member of the negotiating team.

The path to the contract was bumpy. Aspira opposed the unionization of its workforce; it paid consultants to try to sway teachers before the vote to form a union, and once the vote was taken, it sought to block its certification. The staffers held an informational picket in November, saying they wanted a fair salary schedule.

Apt said the mood among teachers was buoyant.

"It's powerful to take charge of your working conditions," she said. "This is not organizing against anybody. This is organizing for ourselves, and our students and our families."

The School Reform Commission turned once-troubled Olney over to Aspira in 2010 to convert to a charter as part of an academic turnaround plan.

Citing concerns about academic performance and Aspira's management and financial practices, the charter office has recommended that Aspira's operating agreement for Olney not be renewed.