(a) The board may decide the application on the basis of the papers and other materials submitted in the matter, or it may in its discretion hear argument or hold a hearing for such purposes as it may consider appropriate. If a hearing is to be held or argument had, the board shall fix a time and place therefor and shall notify the parties and any person which it deems might aid it in arriving at a determination.

(b) In the discretion of the board, interested persons may be allowed to intervene.

(c) The board may affirm, revoke or modify the “unsafe notice” under review, or make such determination as it may deem proper. Such determination shall be effective from a date therein specified until further action by the board or decision of the section 101 proceeding.