Notwithstanding the provisions of any other statute to the contrary, actions for civil or criminal penalties under this act or civil actions for releases of hazardous substances may be commenced at any time within a period of 20 years from the date the unlawful conduct or release is discovered. Actions to recover response costs may be commenced within six years of the date those costs are incurred. The initial action to recover response costs shall be controlling as to liability in all subsequent actions.