A. A site application for new construction that was approved prior to the Rules and Regulations and is still valid. The regulations in effect at the time of approval shall apply, except where portions of the new Rules and Regulations are less stringent;

B. An extension, alteration, or replacement necessitated by the failure of an existing on-site sewage system. In such cases, the repair shall comply to the maximum extent possible to the Rules and Regulations as is permitted by that site; except no work or repair shall create a potential health hazard;

C. Facilities constructed or operated in accordance with a permit or approval issued by the Washington State Department of Ecology or the Washington State Department of Social and Health Services.