(A) Lots of record in the office of the County Recorder prior to 8-1-1978 may be allowed as residential building sites; provided:
(1) They have frontage on an existing public right-of-way or have frontage on an existing easement or other private roadway existing prior to 1-1-1977; and
(2) They have at least 20,000 square feet of area.
(a) Lots smaller than 20,000 square feet may be used as dwelling sites if the owner can prove that adequate sanitary facilities can be provided. Said sanitary facilities must be located on the same lot of record as the dwelling, or on adjacent land which is legally available to the owner. Extraordinary alteration of the lot through land filling or excavation shall not constitute proof of an adequate site for sanitary facilities.
(b) The Board of Adjustment shall decide if lots smaller than 20,000 square feet may be used for dwelling sites in accord with § 155.026(B) of this chapter. The expansion of the floor area of substandard residential uses on lots smaller than 20,000 square feet shall also be reviewed by the Board of Adjustment. Such expansion may be denied or limited by the Board when there is limited space for sewage treatment and/or no alternative sewage treatment site on the lot. The Board of Adjustment may note in its review that a substandard residential use should be used for seasonal use only, if adequate sanitary facilities for year-round occupancy cannot be provided. Holding tanks need not be considered as adequate sanitary facilities for year-round use. In no case shall the expansion of a substandard residential use exceed 50% of the assessed value of the original structure if a holding tank is the only available method for sewage treatment.
(c) In determining if adequate sanitary facilities can be provided, the Board of Adjustment shall require that all standards in § 155.090 of this chapter, sewage treatment and disposal standards be shown to be met. Due to the small lot size, and in areas where community water and sewer systems are not planned to be installed, the Board of Adjustment may require that proposals include a second location for a sewage treatment system. Proposals which can provide for only one site, and require a mound system or other alternative sewage treatment system shall not be considered as adequate sanitary facilities on lots which are predominantly low (less than six feet) in elevation above the ordinary high water mark or water table. The total square footage of any proposed residence shall be limited by the Board on any lot where there is no alternative sewage treatment site available.
(B) In a group of two or more contiguous lots under the same ownership, if an individual lot has less than 20,000 square feet of area, no lot nor lots may be considered as a separate parcel of land for the purposes of sale or development unless each separated parcel and the remainder contains at least 20,000 square feet of lot area.
(C) All other requirements of this chapter are met, including, but not limited to, setback standards and sewage treatment standards.