An error in tabulating the size of Castilleja School's existing classroom buildings could add months of delay to the school's contentious plan to redevelop its campus and expand enrollment — a proposal that the Palo Alto City Council began to review on Monday after nearly five years of passionate community debate.

Dozens of speakers, including Castilleja students, parents, neighborhood residents, teachers, community activists and land-use watchdogs came out to speak for and against the project during the Monday hearing, which was intended primarily to solicit public feedback. The council is scheduled to make some tentative decisions on the project on March 15, though any hope that Castilleja had of securing the city's final approval this month dimmed last Thursday, when planning staff released a memo recommending that the project be remanded to the Architectural Review Board for additional revisions.

The main reason for the staff recommendation was an error that a resident had found in Castilleja's building plan and recently brought to staff's attention. Because of an oversight in interpreting a handwritten diagram on the margin of a 1965 microfiche, Castilleja and the city had initially determined that the existing buildings that the school was looking to replace at its campus in the 1300 block of Bryant Street totaled 84,572 square feet. The number, however, included a 7,000-square-foot basement, which should not have been counted in gross floor area calculations.

With the basement taken out of the equations, the total gross floor area for existing buildings gets reduced to 77,572 square feet. Given that Castilleja has vowed not to increase new square footage as part of its redevelopment project, the revision means that the school will have to reduce 4,370 square feet from its replacement building, which was slated to be 81,492 square feet.

"The amount of gross floor area to be removed is significant in area but a small percentage relative to the overall development," the memo from the Department of Planning and Community Environment stated. "Adjustments to the classroom building adjacent to Kellogg Avenue is expected to introduce more building relief and modulation that may serve to further reduce building mass."

Lorraine Brown, director of communications and community relations at Castilleja, said that as part of the application, the school had researched "hundreds of City permit documents and submitted copies," including an approved building plan from 1965, which was photographed and stored on microfiche.

When Castilleja submitted its application in 2016, the application did not notice that 7,000 square feet of one of the buildings had been designated as a "basement" in handwritten notes in the corner of the building plan, Brown said.

"We were surprised to learn about this oversight; it was an honest mistake that we regret," Brown said in a statement.

The discovery of the microfiche marginalia is expected to delay the decision on the project, which was initially slated for March 15. Now, Castilleja will have to reduce its building by 5% and return to the Architectural Review Board for fresh approval.

The school, Brown said, is "committed to complying with all city regulations."

"It's been a long journey to this moment, and while we hope to minimize any further delay in the process, we will reduce square footage appropriately if the City decides it's necessary after reviewing the errant calculation," Brown said. "Throughout this process, our mission has remained constant: to modernize Castilleja's facilities and expand opportunities for a world-class education to more young women."

Nanci Kauffman, head of Castilleja, said Monday that the school is prepared to reduce its proposed square footage in accordance with the council's direction, but said she hopes this "minor change" will only require a review from an Architectural Review Board's subcommittee, rather than the full board.

In introducing the project on Monday, Kauffman stressed that the campus redevelopment plan is built upon "years of productive compromise."

"To increase opportunities for girls and to enhance our programs in math, science, languages, athletics and performing arts, we are seeking permission to gradually increase enrollment to a maximum of 540 students without increasing traffic," Kauffman said.

The latest procedural hiccup follows a five-year process that has already featured three hearings in front of the Architectural Review Board, six hearings in front of the Planning and Transportation Commission and a review from the Historic Resources Board. While the project has already seen some major revisions along the way, including design revisions that added the underground garage and that reduced the number of trees that need to be removed, the Monday meeting underscored the wide gap that remains between supporters and opponents of the project.

Each side was represented by more than 50 people on Monday, with dozens of others submitting letters of support or opposition. Many speakers lauded Castilleja for being a good neighbor, praised its mission of educating young women and urged the council to support the project, which includes demolition of existing buildings, construction of five new ones, the addition of an underground garage and the relocation of an above-ground swimming pool to an underground location.

But while supporters suggested that the project will further enhance a valuable local treasure, opponents characterized the project as a zone-busting giveaway to a wealthy property owner at the expense of the neighborhood. Many residents scoffed at staff's recent finding that Castilleja's underground garage is in fact not a garage but a "basement" — a conclusion that benefits Castilleja because underground garages typically aren't allowed in single-family districts while basements are. They also suggested that the school's plans are too ambitious and were skeptical of Castilleja's assertion that it can add students without worsening traffic.

Several speakers alluded to Castilleja's history of flouting its enrollment cap of 415 students, which resulted in the city issuing the school a $265,000 fine in 2013.

"Why would the City of Palo Alto allow this private institution to control its own future enrollment limits when they have a history of noncompliance?" Andie Reed, a member of the neighborhood group Preserve Neighborhood Quality of Life Now, asked. "Why should the residents take on all the risk? If the school is so confident they can control traffic, then let them rebuild and earn enrollment increases by proving it."

Leila Moncharsh, an attorney representing PNQLNow, also questioned staff's finding and urged the council not to approve the various variances that Castilleja is seeking as part of the project.

"Yeah, the city can interpret its own code, but it can't just make stuff up," Leila Moncharsh said. "There's no indication in the evidence that I've seen that you can say, 'Oh well, let's just call it a basement, let's go with that,' or, 'It's akin to a basement, let's go with that.'"

Supporters countered that these arguments over zoning provisions obscure the greater issue: the value that Castilleja brings to the city and, more broadly, to Silicon Valley. Several residents noted that the city's proposed conditions of approval for the Castilleja project prohibit the school from worsening area traffic under penalty of having its enrollment increases suspended.

They also observed that Castilleja has already reduced its car trips by 31% since it adopted a stringent "transportation demand management" program that includes carpools and a policy barring staff from solo commuting more than twice a week.

Roy Wang, who lives several blocks from the school, said many of his neighbors support the school's plans, including the underground garage.

"Castilleja's actions have proved to me that they deserve my trust and support," Wang said. "So while we're debating the technical details here, let's not lose sight of the big picture: Castilleja is a treasure in our neighborhood and a treasure in our city."

Most of those who oppose the project in its current form said they have no objections to seeing Castilleja redevelop its campus, as long as it abandons its plans for a new garage and settles for a more modest enrollment increase — a number along the lines of 450 students. Diane Rolfe, who lives on the corner of Emerson Street and Kellogg Avenue, near the school, called Castilleja's plan "poorly designed" and "highly controversial" and suggested that the school's history of exceeding its enrollment limit had made a "mockery of city rules and regulations."

"To enable our neighborhood to be livable and to enable Castilleja to continue to provide outstanding quality education for girls, the present plan needs to be abandoned or changed significantly," Rolfe said.

But Jim Fitzgerald, who supports the project, said the school had already modified its plan repeatedly to meet the many objections from the neighborhood — only to encounter fresh criticism.

"This project has epitomized the metaphor of moving goal posts and one has to ask if the opponents will ever really be satisfied," Fitzgerald said.

Watch the Palo Alto Weekly's Virtual Town Hall on Castilleja

Learn about the key issues that still separate supporters from opponents and the conditions of approval that the City Council will be considering as it decides on the Castilleja School redevelopment plan.