The Board of Zoning and Building Appeals shall have the following powers:
(a)   To hear and decide appeals, filed as hereinbefore provided, where it is alleged by the appellant that there is error in any order, requirement, decision, grant or refusal made by the Building Inspector or other administrative official in the interpretation of the provisions of this section.
(b)   To authorize, upon appeal, in specific cases, filed as hereinbefore provided, such variance from the provisions or requirements of this section as will not be contrary to the public interest; but only in such cases where, owing to special conditions pertaining to a specific piece of property, the literal enforcement of the provisions or requirements of this section would cause undue and unnecessary hardship, and so that the spirit of the section shall be observed and substantial justice done.
(c)   Where, by reason of the exceptional narrowness, shallowness or unusual shape of a specific piece of property on the effective date of this section, or by reason of exceptional topographic conditions, or other extraordinary situation or conditions of such piece of property, or of the use or development of property immediately adjoining the piece of property in question, the literal enforcement of the requirements of this section would involved practical difficulty or would cause unnecessary hardship, unnecessary to carry out the spirit and purpose of this section, the Board shall have the power to authorize a variance from terms of this section so as to relieve such hardship, and so that the spirit and purpose of this section shall be observed and substantial justice done. In authorizing a variance, the Board may attach thereto such conditions regarding the location, character and other features of the proposed structure or use as it may deem necessary in the interest of the furtherance of the purposes of variance, with attached conditions; the Board shall require such evidence and guarantee or bond, as it may deem to be necessary, that the condtions attached are being and will be complied with.
(d)   No such variance in the provisions or requirements of this section shall be authorized by the Board unless the Board finds, beyond reasonable doubt, that all the following facts and conditions exist:
(1)   That there are exceptional or extraordinary circumstances or conditions applying to the property in question, or to the intended use of the property, that do not apply generally to other properties or classes of uses in the same district.
(2)   That such variance is necessary for the preservation and enjoyment of substantial property rights possessed by other properties in the same district and in the same vicinity.
(3)   That the authorizing of such variance will not be of substantial detriment to adjacent property, and will not materially impair the purposes of this chapter or the public interest.
(e)   No grant of variance shall be authorized unless the Board specifically finds that the condition or situation of the specific piece of property, or the intended use of such property for which variance is sought, one or the other or in comobination, is not of so general or recurrent a nature as to make reasonably practicable the formulation of general regulation for such conditions or situation.
(f)   The Board shall have the power to hear and decide, in accordance with the provisions of this section, applications, filed as hereinbefore provided, for special exceptions in the use of land, buildings and other structures; for interpretation of the Zoning Map; for decisions upon other special questions on which the Board is authorized by this section to pass. In considering a special exception or interpretation of the Zoning Map, the Board shall give due regard to the nature and condition of all adjacent uses and structures; and in authorizing a specific exception, the Board may impose such maintenance and operation, in addition to those expressly stipulated in this section for the particular exceptions, as the Board may deem necessary for the protection of adjacent properties and the public interest.
(g)   The Board shall have the power to permit the restoration, extension, alteration, or change of a nonconforming use.
      (1978 Code Sec. 1270.08)