If the corrective action is not taken on or before the date specified in the notice served pursuant to Section 4608, the department may take, or contract for the taking of, such corrective action and recover the expenses of the corrective action as provided in Section 4610. Where the person responsible makes a request for public hearing, the board, after at least 15 days written notice, shall hold a public hearing to hear the objections to the proposed action. The board may, but need not, conduct the hearing in accordance with the applicable provisions of Chapter 5 (commencing with Section 11500) of Part 1 of Division 3 of Title 2 of the Government Code. At the conclusion of the hearing, the board may make an order specifying the action to be taken by the person responsible to correct the violation, setting the time limits for such action, and authorizing the taking of such action by the department if the person responsible does not do so within the specified time.