(a) An appeal under this subchapter is de novo and based on the test year presented to the municipality adjusted for known changes and conditions that are measurable with reasonable accuracy.
(b) The railroad commission shall enter a final order establishing the rates the railroad commission determines the municipality should have set in the ordinance to which the appeal applies.
(c) If the railroad commission fails to enter a final order within 185 days after the date the appeal is perfected, the rates proposed by the gas utility are considered to be approved by the railroad commission and take effect on the expiration of the 185-day period.