Lot area and width. For uses serviced by the Borough sewer system, a lot area of not less than 7,200 square feet per family shall be provided for every building hereafter erected or used, in whole or in part, as a dwelling. For uses not serviced by the Borough sewer system, a minimum lot area of 12,000 square feet shall be provided. Each lot shall have a frontage on at least one street of not less than 60 feet.