Except as otherwise provided in Section 10504.5 or 10506, work on all projects shall be performed under contract awarded in accordance with Section 10501, except that it may be done on a time and materials basis, by contract upon informal bids, by University of California employees, by day labor under the direction of the regents, or by a combination thereof, in case of emergency due to an act of God, earthquake, flood, storm, fire, landslide, public disturbance, vandalism, or failure that causes damage to a university-owned building or structure, university-owned real property, or any improvements thereon, when that work or those remedial measures are required immediately and are necessary to protect the public health, safety, and welfare.