In exercising its duties, the Board may, as long as such action is in conformity with the terms of this chapter, reverse or affirm, wholly or partly, or modify the order, requirement, decision, or determination appealed from the Administrator and may make such order, requirement, decision, or determination as ought to be made. For the purpose of this chapter, the Board has the following specific responsibilities:
(a) To hear and decide appeals where it is alleged there is an error in any order, requirement, decision, or determination made by the Administrator;
(b) To authorize such variances from the terms of this chapter as will not be contrary to the public interest, where, owing to the special conditions, a literal enforcement of this chapter will result in unnecessary hardship and so that the spirit of this chapter shall be observed and substantial justice done;
(c) To hear and decide upon applications for interpretation of the district map where there is any uncertainty as to the location of a district boundary. After notice to the owners of the property affected, and after public hearing with notice as required by § 15.1-431 of the Code of Virginia, 1950, as amended, the Board may interpret the map in such way as to carry out the intent and purpose of the ordinance for the particular section or district in question. The Board shall not have the power to change substantially the locations of district boundaries as established by this chapter.