Amends GS 130A-336 to allow improvement permits or authorizations for wastewater system construction that were issued by a local health department between January 1, 2000, through January 1, 2015, which have not been acted on and would have otherwise expired, to remain valid until January 1, 2024, rather than January 1, 2020, without penalty unless there are changes in hydraulic flows or wastewater characteristics from the original evaluation.