Sec. 8. (a) In determining the existence and amount of exceptional benefits resulting from the purpose of sewage collection, treatment, and disposal, the appraisers shall consider as exceptionally benefited the following:
(1) Real property that would not pay special benefits taxes for the support of the system.
(2) Real property that requires greater capacity of collecting or treating equipment because of intensive use.
(b) The determination of exceptional benefits from the accomplishment of this purpose is always subject to amendment or supplement as a result of changed land use.
(c) Exceptional benefits may be assessed on an annual basis as long as the exceptional conditions exist.