Three top officials are leaving Santa Rosa City Schools as the school year ends, creating vacancies in positions considered key to a series of academic and discipline changes the district is pursuing.

George Valenzuela, the district's attorney, is resigning his post after more than 16 years in the district; chief technology officer Rainer Wachalovsky is retiring after more than six years; and Anastasia Zita, assistant superintendent of curriculum and instruction in secondary schools, was released from her position effective June 30.

A fourth official, Gail Eagan, retired from her post as assistant superintendent of elementary level curriculum and instruction in December and has been working on an interim basis on the establishment of the district's new dual-immersion Spanish language charter school.

The changes come at a critical time for Sonoma County's largest school district as the two curriculum directors are expected to oversee the dramatic overhaul of what is taught in California classrooms as part of the implementation of common core standards.

Technology is also expected to play a key role in the how lessons are delivered — adding an extra element of urgency to finding a new chief technology officer.

Santa Rosa City Schools is also examining its past practices related to suspensions and expulsions after the district was found to have the fourth highest per capita suspension rate in the state among larger school districts.

The school district attorney plays a key role in implementing district discipline policy.

First-year Superintendent Socorro Shiels said the departures are a natural evolution that is occurring across industries as Sonoma County's workforce ages.

"Healthy organizations just have to plan on that," she said.

"There are exciting opportunities in front of us and we are excited for the right people to join us," she said.

Sonoma County's largest school district is in Year 3 of Program Improvement sanctions under the federal No Child Left Behind law, but none of the departures are related to the district's status, Shiels said.

"There was gallant work done in trying to understand the Program Improvement process," Shiels said. "I knock on wood that the state realizes that this kind of accountability didn't produce the kind of classrooms we want for our children in the state of California."

District officials will begin interviewing for some positions this week and all are expected to eventually be filled.

In addition to the departures at the district office, 25 teachers, staff and administrators have announced their intention to retire. Those totals are in line with departures this time last year, when 29 employees announced their retirement by July.

California is one of 45 states that have adopted the new common core standards, and education advocates have expressed concern that districts will not be able to have the new system in place by the deadline of the 2014-15 school year.

But Santa Rosa teachers union president Andy Brennan said the overhaul of curriculum makes it a good time to make changes in the district office.

"I think if change in personnel was going to happen, now is the best time because we are in the earliest stage," he said. "We haven't really started implementing stuff so whoever is going to come in really gets to come in at the ground floor instead of when a plan is already in place."

Brennan praised Shiels for including teachers in the early stages of screening replacement candidates.

"She is really reaching out, trying to be inclusive," he said.

Shiels said she doesn't "expect any gaps or slow downs at all.

"We have depth in our bench in an organization our size," Shiels said. "The people that have worked with them for years are still here."

Staff Writer Kerry Benefield writes an education blog at extracredit.blogs.pressdemocrat.com. She can be reached at 526-8671, kerry.benefield@press democrat.com or on Twitter @benefield.