An environmental covenant that complies with this subtitle runs with the land. An environmental covenant that is otherwise effective is valid and enforceable even if: It is not appurtenant to an interest in real property; It can be or has been assigned to a person other than the original holder; It is not of a character that has been recognized traditionally at common law; It imposes a negative burden; It imposes an affirmative obligation on a person having an interest in the real property or on the holder; The benefit or burden does not touch or concern real property; There is no privity of estate or contract; The holder dies, ceases to exist, resigns, or is replaced; or The owner of an interest subject to the environmental covenant and the holder are the same person. An instrument that creates restrictions or obligations with respect to real property that would qualify as activity and use limitations except for the fact that the instrument was recorded before October 1, 2005, is not invalid or unenforceable because of any of the limitations on enforcement of interests described in subsection (b) of this section or because it was identified as an easement, servitude, deed restriction, or other interest. This subtitle does not apply in any other respect to such an instrument. This subtitle does not invalidate or render unenforceable any interest, whether designated as an environmental covenant or other interest, that is otherwise enforceable under state law.