[§128D-22]  Exemption from duplicative regulation.  When there has been a response to a release pursuant to an order issued under federal law, the director may use this chapter to address the same release provided that:

     (1)  The release creates an imminent and substantial harm to the public health or welfare; and

     (2)  The federal law has not provided a remedy consistent with the state contingency plan.

In those circumstances, the director shall avoid actions in conflict with federal law.  A single release may be addressed either by CERCLA or by this chapter, but not both, except in the case of a joint enforcement.  Nothing in this chapter shall prevent the director from taking action pursuant to the common law or other statutory provisions necessary to protect the public health and welfare, safety, or the environment. [L 1991, c 280, pt of §1]