In specific cases, the board of adjustment may authorize by permit a variation of the application of the use, height, and area district regulation herein established in harmony with their general purpose and intent as follows:
A. Permit a temporary building for commerce or for industry in a residence district which is incidental to a residential development, such permit to be issued for not more than a period of one year.
B. Permit the erection and use of a building or the use of land in any location for a public service corporation for public utility purpose which the board admits reasonably necessary for the public convenience and welfare.
C. Interpret the provisions of this title in such a way as to carry out the intent and purpose of the plan, as shown upon the building zone map, fixing the several districts accompanying and made part of this title where the street layout actually on the ground varies from the street layout as shown on the building zone map aforesaid.
D. Where there are no practical difficulties or unnecessary hardships in the way of carrying out the strict letter of this title, the board of adjustment shall have the power in passing upon appeals to vary or modify the application of any of the regulations or provisions of this title relating to use, construction or alterations of buildings or structures or the use of land so that the spirit of this title shall be observed, public safety and welfare secured, and substantial justice done. (1997 Code § 17.44.030)