Any permanent closure, pursuant to Pennsylvania Department of Environmental Protection regulations, of an aboveground or underground petroleum or petroleum derivative storage tank or tank system shall include the removal of the tank or tank system in its entirety, including all associated pipes, and further, including tank(s) discovered by chance during removal. All aboveground or underground petroleum or petroleum derivative storage tanks or tank systems to which Pennsylvania Department of Environmental Protection regulations do not apply shall be removed in their entirety, including all associated pipes, and further, including tank(s) discovered by chance during removal, upon a cessation of use of the tank or tank system. A period of six months of continuous nonuse of the tank or tank system shall presumptively constitute cessation of use.