On Monday night, at the Lower Merion School Board meeting, there was an unusual occurrence. A non-unanimous vote followed an almost unheard of contentious public discussion. Board President Melissa Gilbert and outgoing member David Federman sparred over what appears to be a “placeholder plan” for improvements at Harriton High School. Gilbert is concerned that the new Lower Merion zoning code could conceivably reduce the amount of impervious surfaces permitted at Harriton. And that would limit the district’s ability to build new science facilities at the school.