(1) unique and peculiar conditions to the applicant's particular situation which impose a substantial technological, financial or safety burden upon the applicant or the public;

(2) that because of such uniqueness, there is no reasonable possibility that the applicant's property or, if no property is involved, the continuation of the applicant's business, enterprise, use or activity will bring a reasonable return following conformity with the regulations of the commission;

(3) that the proposed activity will have no adverse impact on the public health, safety or welfare, the environment or the resources of the park; and

(4) that the granting of a variance will not alter the essential character of the area in which the proposed use or activity is located, and will not lead to congestion in the park.