(a) The board may temporarily suspend any permit issued pursuant to this chapter prior to any hearing if the board determines that the action is necessary to prevent or mitigate an imminent or substantial endangerment to the public health or safety or the environment. (b) The board shall notify the holder of the permit of the temporary suspension and the effective date thereof and, at the same time, shall serve the person with an accusation. (c) Upon receipt by the board of a notice of defense to the accusation from the holder of the permit, the board shall, within 15 days, set the matter for a hearing, which shall be held as soon as possible, but not later than 30 days after receipt of the notice. (d) The temporary suspension shall remain in effect until the hearing is completed and the board has made a final determination on the merits, which shall be made within 60 days after the completion of the hearing. If the determination is not transmitted within this period, the temporary suspension shall be of no further effect.