Portland Public Schools is seeking $548 million in funding for district-wide school modifications, and is expected to send the request to voters in a bond measure on the May 2011 election ballot.

The district serves 47,000 students in 85 neighborhood and focus schools, plus special programs and alternative schools. Most of the district’s buildings were built before 1960 — and many are more than 65 years old — and have never been modernized.

The proposal would use a “pay as you go” model to minimize long-term debt and interest costs, through a cycle of bond measures to provide the funds. The measure would cost just under $25 a month for the median household. Work will begin in summer 2011 if voters pass the six-year bond measure.

The program would rebuild three high schools, Cleveland, Jefferson and Roosevelt, plus five elementary/K-8 schools. In addition, all other schools in the district would receive safety and structural updates to the building systems, including replaced roofs and mechanical systems, improved ADA accessibility, new fire alarms and seismic upgrades. Schools will also receive updated science labs and physical education spaces to improve the learning environment.