• An onsite wastewater treatment system must be closed whenever use of the system is discontinued following connection to a sanitary sewer or following condemnation or demolition of a building or property or due to the construction of another onsite wastewater treatment system. • Tank • Pump the tank of all liquids and solids then fill the tank with earth and tamp completely so there are no voids; or • Pump the tank of all liquids and solid then remove the tank and fill the void with earth so there are no voids. The earth must be mounded to provide for future settling. • Lagoon • Drain the lagoon completely of any liquids then remove the fence and scrape out and properly dispose of any settled solids and liner material. • Fill the lagoon with earth. The dirt must be mounded over the lagoon area to provide for future settling.