19.3 The Authority shall procure that the Authority's Representative promptly, and in any event within [ ] Business Days of receipt of notice pursuant to Clause 19.2.1, issues an instruction to Project Co specifying what action the Authority's Representative requires Project Co to take in relation to such discovery.
19.4 Project Co shall promptly and diligently comply with any instruction issued by the Authority's Representative referred to in Clause 19.3 above (except and to the extent that such instruction constitutes an Authority Change pursuant to Clause 19.6 below in which case the provisions of Schedule Part 16 (Change Protocol) shall apply), at its own cost.
19.5 If directed by the Authority's Representative, Project Co shall allow representatives of the Authority to enter the Site for the purposes of removal or disposal of such discovery provided that such entry shall be subject to the Authority complying with all relevant safety procedures, which shall include any relevant construction phase plans and health and safety plans for the construction of the Facilities, the Contractor's Site Rules from time to time and any reasonable directions with regard to site safety that may be issued by or on behalf of the Contractor's Site Manager from time to time.
19.6 If, in relation to such discovery, the Authority requires Project Co to carry out works (being any work of alteration, addition, demolition or extension or variation in the Works) which are not works which would be necessary for the purpose of compliance with Law or any Consents, it must issue an Authority Change Notice in accordance with the provisions of Schedule Part 16 (Change Protocol).