Mo. Rev. Stat. § 393.291

A steam heating company having fewer than one hundred customers in this state may file under a small company rate procedure promulgated by the commission which shall be consistent with 4 CSR 240- 3.240 by giving notice to the secretary of the commission, the public counsel, each customer, and each gas corporation or electric corporation providing utility service in the area. Any customer, gas corporation, or electric corporation responding within thirty days of the date of the notice shall be entitled to copies of all filings subsequently made in the case and may participate in any conferences or hearings therein.