Notwithstanding any other provisions of this Chapter, a separate lot of at least 7,500 square feet with a minimum width of 50 feet existing in separate ownership at the time of passage of this Chapter may have constructed thereupon a single-family dwelling provided that all necessary approvals from the Board of Health for water and sewer have been secured. The prevailing setback in the neighborhood shall be maintained and a minimum side yard of 10 feet shall be maintained.