A former school superintendent’s retirement benefits have been cut after a state agency determined the administrator’s benefit calculation was “overstated.” Former Grass Valley School District Superintendent Jon Byerrum’s retirement benefit will be reduced by about $6,000 annually, according the California State Teachers’ Retirement System. This brings his annual pension down from $69,400 to $63,400. Byerrum’s pension came under scrutiny in June when Nevada County’s Civil Grand Jury reported that the former administrator received a nearly $13,000 raise that was not on any school board meeting agendas or minutes, and none of its members recalled discussing, granting or voting on the …