(a) Before the 21st day after the date the person receives notice under Section 481.303, the person in writing may:
(1) accept the determination and recommended penalty; or
(2) make a request for an informal hearing held by the department on the occurrence of the violation, the amount of the penalty, or both.
(b) At the conclusion of an informal hearing requested under Subsection (a), the department may modify the amount of the recommended penalty.
(c) If the person accepts the determination and recommended penalty, including any modification of the amount, or if the person fails to timely respond to the notice, the director by order shall approve the determination and impose the recommended penalty.