b) If the owner or operator of an emission unit elects to use the provisions of subsection (a) of this Section, the following procedures shall apply, depending on the relevant circumstances:

1. 1) If a representative of the Agency is on-site for the purpose of witnessing the emissions test, the owner or operator of the emission unit or an authorized representative may request permission from the Agency's representative to change the procedures, methods, or operating parameters of the emissions test as specified in the test plan, submitted pursuant to the provisions of Section 283.220 of this Part, provided that the change is a minor deviation, as defined in Section 283.130 of this Part.

   1. A) If the Agency representative approves the minor deviation, all test runs performed with this minor deviation may not be deemed invalid test runs by the Agency on the sole basis of the minor deviation.
   2. B) If the Agency representative disapproves the change to the procedures, methods, or operating parameters of the emissions test as specified in the test plan, then the owner or operator of the emission unit or an authorized representative may elect to perform the emissions test with the change. However, the Agency may subsequently disapprove the emissions test results if it finds that a valid test run was not obtained as a result of the change.
2. 2) If an Agency representative is not on-site for the purpose of witnessing the emissions test, the owner or operator of the emission unit or an authorized representative may elect to change the procedures, methods, or operating parameters of the emissions test as specified in the test plan, provided the change is a minor deviation, as defined in Section 283.130 of this Part. However, the Agency may disapprove the emissions test results if it finds that a valid test run was not obtained as a result of the change.