(a) At any time after the award of an original job order and during the time the work thereunder is being performed, additional or extra work or changes in the work covered by the job order may be directed by the representative of the Authority.

(b) Such additional or changed work shall be directed by a written Change Order as provided in Article 6 of the NSA-LUMPSUMREP Contract.

(c) A supplemental job order shall be issued to the Contractor covering such Change Order(s), which supplemental order shall include the agreed amount of contract price increase or decrease and any revision in the completion date of the job order work, as modified by the Change Order(s).

(d) In the event a change in the contract price or revision in the completion date cannot be agreed upon the representative of the Authority shall determine the contract price or revised completion date and issue a supplemental job order to the contractor who shall proceed with the work covered by the Change Order(s) and the Contractor may appeal such contract price or revised completion date as provided in Article 27 of the NSA-LUMPSUMREP Contract.