The Board of Zoning Appeals shall have the power to hear and decide appeals made for exceptions to and variances in, the application of resolutions, ordinances, regulations, measures and orders of administrative officials or agencies governing zoning and building in the municipality, as may be required to afford justice and avoid unreasonable hardship, subject to such procedures as shall be established by Council and subject further to such reasonable standards as shall be prescribed by Council, including, but not limited to, the existence of practical difficulties or unnecessary hardships in the strict interpretation of the aforesaid ordinances, resolutions, regulations, measures or orders provided that the granting of such exception or variance will be in harmony with the general purpose and intent thereof and that the public health, safety, and general welfare will continue to be secured and substantial justice done.