Mountain Fuel Supply Co. has filed a petition for rehearing regarding a 1990 rate case that resulted in a negligible rate increase for the company.

Mountain Fuel was seeking a $10 million rate increase in the September rate case. The Public Service Commission order issued Nov. 21 granted only a $76,000 increase.The rehearing request contests almost every element of the November order. The petition states, "The issues for which rehearing is sought center around those aspects of the report and order that Mountain Fuel believes lead to rates that do not reasonably reflect the conditions that will exist during the period rates will be in effect, a penalty imposed on the company through a reduction in the authorized rate of return that the company believes is unwarranted, and the uncertainty created by those portions of the report and order that address the burden of proof in connection with interaffiliate costs incurred by the company."

Mountain Fuel officials contend that the commission's choices of a test year, rate base and other related rate-making elements did not result in just and reasonable rates as required by state law and applicable case law. Also, officials say, the commission's decision to require the use of a historic test year was not based on evidence presented in hearing and the commission's order to use an average rather than a year-end rate base also was not based on sufficient evidence in the hearing record. Mountain Fuel also argues that the commission improperly applied its own rule to annualize costs used in the case and improperly rejected the concept of post-test year adjustments.

The company also contends the commission order has contributed to regulatory lag and cost under recovery and has circumvented Utah law in this regard.

The commission has given those wishing to respond to Mountain Fuel's rehearing request until Friday, Jan. 4, at 5 p.m. to file their responses before deciding whether or not to grant Mountain Fuel's request.