Subject to the Subdivision Map Act, the advisory agency may authorize exceptions to any of the requirements and regulations set forth in this chapter. Application for such exception shall be made by the subdivider, stating fully the grounds for the application and the facts relied upon, and the subdivider shall grant such additional time as may be required by the advisory agency for the consideration of the exception. Before granting any such exception, the advisory agency shall find:
a. That there are unusual circumstances or conditions affecting the property;
b. That the exception is necessary for the preservation and enjoyment of a substantial property right of the applicant;
c. That the granting of the exception will not be materially detrimental to the public welfare or injurious to other property in the territory in which the property is situated.