In unusual circumstances, when the application of these regulations appears impracticable or unjust to either party, or discriminatory to other customers, the utility or applicant may refer the matter to the Commission for modification of the regulations or for approval of special conditions before commencing construction. Requests to the Commission for exemption from the requirements for underground installation of a telephone distribution system or a service line shall be in writing and shall include the following: Description of the probable impact on the environment if the overhead line is constructed, including proposed overhead construction; Estimate of the installation cost of underground, by major elements; Number of customers to be served from the proposed system or line; and Property plat indicating the physical features, potential customers, and system or line layout (underground and overhead).