Since it began meeting last summer, the Andover High School building committee made the decision to move forward without state aid and conducted extensive research with students, staff and administrators to develop an educational plan that will inform design decisions for a new school or renovating the existing one.

It has done countless hours of community outreach to help Andover residents understand the need to address the aging high school and laid out an aggressive timeline o bring the project to special town meeting for final approval next January. It has considered conceptual designs for new construction and renovations and, last month, narrowed those designs down to tow two — one new construction, one renovation — for further exploration.

But, all along the way, it has resisted calls to discuss the cost of such a massive project and what impact it will have on Andover taxpayers.

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That will change at the March 23 building committee meeting, which will include a presentation of preliminary cost projections. Chair Mark Johnson has repeatedly stressed these will be “high level” estimates, and a more detailed breakdown of the cost won’t come until after a decision has been made on new construction or renovation and detailed designs can be completed.

Johnson knows a massive school building project without support from the Massachusetts School Building Authority “will not be an easy process.” And the lack of preliminary cost numbers before the committee ruled out all but two designs could make that process even more difficult.

“I support the project. I agree we need a new high school,” Andover Select Board member Christian Huntress said at the board’s Feb. 13 meeting. “I just struggle with how we’re going to pay for it. What I struggle for with this timeline is we’re being asked to approve it five weeks before we’ll have any brush with an idea of the cost.”

At the same meeting, select board candidate Kevin Coffey, who will face incumbent Laura Gregory in the town election on March 28, echoed Huntress’s demands for cost estimates.

“I’ve been asking repeatedly for costs, so I appreciate Chris’s line of questioning. We do all agree we have to do something at the high school — I’m not at all confused about that,” Coffey said. “But when it is likely to be, by a considerable margin, the largest expense this town has ever taken, it seems to me getting some basic estimate of numbers on the table early makes a lot of sense.”

The current high school was designed for 1,200 students in grades 10-12 and opened along with Dunn Gym in 1968. The Collins Center was added in 1983. The last significant renovation came in 1995, when the science wing and field house were added, and the school was expanded to include ninth graders. AHS is just one of three high schools in Essex County that has not been replaced or had major renovations in the past 25 years.

Both plans being sent for pricing would keep the field house but demolish the science wing. A replacement or renovation could increase the size of the school by as much as 60.5 percent, according to preliminary schematics.