In the establishment of one or more new grades in grades nine through twelve, the principle set forth in WAC 392-348-205 through 392-348-260 above concerning program, specialized services, staff and corps and size of respective grade or grades as related to potential total enrollment of the proposed secondary school shall apply: Provided, That the school district shall have satisfied all other requirements as herein prescribed. The establishment of each such grade shall be subject to prior approval by the superintendent of public instruction.