Dworetzky, who had done his own calculations, was skeptical. He said his own estimate was "many, many times higher."
Later, officials said that an error had been made and that $139 million was the true cost over five years.
The district hopes to reduce the figure to $119 million through an agreement with Mastery Charter Schools, which would forgo up to 600 seats that its Lenfest campus is entitled to.
Each new charter seat costs the district about $7,000 annually.
Citing those cost concerns, Dworetzky and Commissioner Lorene Cary voted against the expansions of New Foundations Charter School and KIPP Philadelphia Charter. Chairman Pedro Ramos and Commissioners Feather Houstoun and Wendell Pritchett voted for the renewals.
Neither New Foundations, in Holmesburg, nor KIPP, in North Philadelphia, was up for renewal, but both said they needed permission to grow now.
Both schools agreed to cap their enrollments and said they would give preference to students from certain catchments - the overcrowded Northeast for New Foundations and, for KIPP, students from FitzSimons and Rhodes High Schools, which the district just closed.
New Foundations will increase by 211 students and KIPP by 106.
Dworetzky, who has sounded similar themes at charter-renewal hearings in past months, made it clear that he thinks Renaissance charters and Promise Academies - the district's turnaround models - are a better way to expand high-performing seats, rather than opening new schools.
"That's a major part of our job, improving all the schools," Dworetzky said.
"The best way to improve schools is to work on the improvement of district schools first," she said. "That is the most cost-effective way."
Lori Shorr, Mayor Nutter's chief education officer and a special adviser to the SRC, pointed out that many charter operators choose not to pursue district turnarounds.
Asked why his organization wasn't pursuing Renaissance schools, Marc Mannella, CEO of KIPP Philadelphia, said he had a lot of respect for organizations that did.
But "we have no idea how to do it," he said of the turnaround approach, in which charter organizations take control of an existing school. The organization prefers a ground-up approach, Mannella said.
The SRC did not vote on seven charters up for renewal, including two schools under investigation for possible cheating on state tests and three schools whose financials are still under review by the district. It was not clear when those charters might come up for a vote.
Imhotep Institute Charter High School and Philadelphia Electric and Technical High School are two of 53 Philadelphia schools being probed for possible state-exam improprieties. State officials have asked that the SRC hold off on considering their renewals until its investigation is complete.
World Communications Charter, Laboratory Charter, and Planet Abacus Charter are all awaiting the results of a district financial review.
Two more charters - Belmont Academy and Belmont Charter - have been recommended for renewal, but they were not voted on. District officials did not say why those renewals were not brought before the SRC Friday.
Contact Kristen Graham at 215-854-5146 or email@example.com, or follow on Twitter @newskag. Read her blog, "Philly School Files," at www.philly.com/schoolfiles.