(1) For the purpose of ascertaining the matters and things specified in section 40-4-110, concerning the value of the property of public utilities, the commission may cause a hearing to be held at such time and place as the commission may designate. Before any hearing is had, the commission shall give the public utility affected thereby at least thirty days' written notice, specifying the time and place of such hearing, and such notice shall be sufficient to authorize the commission to inquire into the matters designated in this section and pursuant to section 40-6-111, but this provision shall not prevent the commission from making any preliminary examination or investigation into the matters herein referred to or from inquiring into such matters in any other investigation or hearing. All public utilities affected shall be entitled to be heard and to introduce evidence at such hearing. The commission is empowered to resort to any other source of information available. The evidence introduced at such hearing shall be reduced to writing and certified under the seal of the commission. The commission shall make and file its findings of fact in writing upon all matters concerning which evidence has been introduced before it which in its judgment have bearing on the value of the property of the public utility affected. Such findings shall be subject to review by the district court in the same manner and within the same time as other orders and decisions of the commission.

(2) The findings of the commission so made and filed, when properly certified under the seal of the commission, shall be admissible in evidence in any action, proceeding, or hearing before the commission or any court, in which the commission, the state, or any officer, department, or institution thereof, or any county, city and county, municipality, or other body politic and the public utility affected may be interested, whether arising under the provisions of this title, or otherwise, and such findings, when so introduced, shall be conclusive evidence of the facts therein stated as of the date therein stated under conditions then existing, and such facts can only be controverted by showing a subsequent change in conditions bearing upon the facts therein determined. The commission, from time to time, may cause further hearings and investigations to be had for the purpose of making revaluations or ascertaining the value of any betterments, improvements, additions, or extensions made by any public utility subsequent to any prior hearing or investigation, and may examine into all matters which may change, modify, or affect any finding of fact previously made, and at such time may make findings of fact supplementary to those theretofore made. Such hearings shall be had upon the same notice and be conducted in the same manner, and the findings so made shall have the same force and effect as is provided for such original notice, hearing, and findings. Such findings made at such supplemental hearings or investigations shall be considered in connection with and as a part of the original findings except insofar as such supplemental findings shall change or modify the findings made at theoriginal hearing or investigation.