Be it enacted by the Senate and House of Representatives in General Court assembled, and by the authority of the same, as follows:

Notwithstanding any general or special law to the contrary, no dwelling shall be constructed on any lot in the town of Wilmington containing less than 10,000 square feet of land or having less than 100 feet of frontage; provided, that the planning board may authorize by special permit construction of one single family dwelling on such a lot, which does not conform with the area or frontage requirements of the zoning but which contains at least 5,000 square feet and has at least 50 feet of frontage, provided that such lot met any applicable requirements for area and frontage at the time such lot was recorded or endorsed and that such lot has not been held in common ownership with any adjacent land since the date of nonconformance with area or frontage requirements, upon a finding, after consideration of all pertinent factors, including the provisions for the disposal of waste, that construction and maintenance of a single family dwelling on such lot will be consistent with public health, safety, and welfare and without any substantial detriment to the public good.