Where public water and/or sewer facilities are accessible, a lot area of not less than 12,500 square feet per family shall be provided for every building hereafter erected or used in whole or in part as a dwelling. Each lot shall have a frontage on at least one street of not less than 85 feet; provided, however, that a permit may be issued by the Zoning Administrator for lots of record at the effective date of this amended subsection which have a width of 75 or more feet and which have a lot area of 10,000 or more square feet. Lots of smaller dimensions shall be referred to the Planning Board, in accordance with the provisions of § 700-47.