Former interim Superintendent Tommy Kranz initially estimated the cost of building the three new schools — George Mason Elementary, E.S.H. Greene Elementary and a new middle school on Hull Street Road — at $110 million, but now the price tag has ballooned to $140 million.

Burrell and Stone said original information given to the School Board didn’t include site work and other project costs, only building construction. The city is also spending less on design fees and construction assistance with these new schools than for schools built between 2010 and 2015, according to Burrell and Stone.

The two members of Mayor Levar Stoney’s administration also pointed to data from the Virginia Department of Education that says the cost per square foot to build elementary and middle schools has increased roughly 80 percent since 2009-10, far outpacing the general inflation rate, which has gone up about 15 percent in the same period.

Since 2015, when the first plan was approved, the rate of inflation in the U.S. has increased 8 percent. Construction inflation is normally about double the rate of inflation, according to Ed Zarenski, a construction economics analyst, but has been three times the inflation rate over the past five years.

“You have to factor in inflation,” Kranz said. “That drives up the cost.”