The city must start over its controversial plan to let a Lower East Side charter school expand in city space but may proceed with another, the state education department ruled yesterday.

State Education Commissioner David Steiner threw out the city’s plan to allow Girls Prep Charter School to expand its middle school grades in the building it shares with two district schools, ruling that the city did not properly report the plan’s impact on disabled students who attend school in the building.

But in a separate ruling, Steiner argued that the city did provide enough information about its plan to let Brooklyn’s PAVE Academy Charter School expand in the building it currently shares with P.S. 15.

Both plans have prompted bitter space battles this year between the charter schools and teachers and parents at the district schools who share the buildings. Both charters want to expand the number of grades they serve; opponents of the expansion argue that the plans would squeeze the students at the district schools in the building.

The Girls Prep plan, which Steiner overturned, was complicated by the fact that one of the schools that shares the building is P.S. 94, a school for students with autism run by the Department of Education’s special district for severely disabled students.

P.S. 94 parents have complained that they were excluded from conversations about space sharing at the school from the start. And the final space sharing plan, which the citywide school board approved in February, did not detail how the change would affect P.S. 94 students.

When the city plans to significantly change the way a school building is used, it is required to prepare an “educational impact statement” (EIS) analyzing how the change will affect schools and students in the building. City officials argued that its schools for the most severely disabled students should be exempt from that requirement, since the city frequently has to re-locate programs to accommodate the students’ special needs. But Steiner responded that state education law requires the city to prepare an EIS for any change in school use.

“Accordingly, DOE’s contention that District 75 schools should be excluded is not supported by the plain language of the statute,” Steiner wrote.

A DOE spokesman said the city was reviewing the decision and its options to proceed.

Here’s Steiner’s ruling on P.S. 94 and Girls Prep. The PAVE and P.S. 15 ruling is below.