Ariz. Rev. Stat. § 49-1016 – Responsibilities of owners and operators

A. Unless specifically indicated otherwise, the responsibilities of this chapter are imposed on the owner and the operator of an underground storage tank. If the owner and operator of an underground storage tank are separate persons, only one person is required to discharge any specific responsibility. Both persons are liable in the event of noncompliance.
B. The liabilities and responsibilities for releases of regulated substances imposed pursuant to this chapter shall apply even if the conduct that resulted in the release or the release itself occurred before August 13, 1986.
C. If a person comes into the possession or control of property where an underground storage tank is located and the person is not the owner as defined in section 49-1001.01, the person shall:
1. 1. Notify the department in writing specifying the tank's location, size and use, if known, if the owner has failed to do so.
2. 2. Notify the department of each release or suspected release from the tank as soon as practicable if the owner or operator has failed to do so.
3. 3. If the person voluntarily undertakes to remove or otherwise close the tank, do so in a safe and secure manner which prevents releases of regulated substances and in accordance with standards prescribed by the director pursuant to section 49-1008, except for the requirement to perform corrective action.
4. 4. If the person voluntarily undertakes corrective action, take corrective action in a manner consistent with federal regulations and rules adopted by the director pursuant to section 49-1005.
D. A person acting under subsection C of this section shall not incur the liability of an owner.
E. No agreement or conveyance shall be effective to transfer the obligations imposed by this chapter from the owner or operator of any underground storage tank, or from any person who may be liable for a release or threat of release under this chapter, to any other person. Nothing in this section shall bar any agreement to insure, hold harmless, or indemnify a party to such agreement for any liability under this chapter nor shall it bar a cause of action that an owner or operator or any other person has or would have against any person.
F. In any action brought by the department under section 49-1013, the state bears the burden of establishing that an owner or operator has violated the requirements of this chapter. An owner or operator is responsible for only the owner's or operator's contribution to any contamination that creates liability under this chapter. No party bears the burden of proving any person's contribution to the contamination in any informal or formal appeal pursuant to section 49-1017, subsection D, section 49-1019, subsection D or section 49-1091.
G. If there is prima facie evidence that other identified or unidentified persons not at the owner's or operator's facility have contributed to the contamination, the owner or operator shall be responsible to take corrective action only to the extent, by area, of the owner's or operator's release. The owner or operator shall not be required to identify or to prove the contribution of any contributing persons in order to limit the owner's or operator's own liability, but the owner or operator shall provide to the department any information the owner or operator knows regarding the identity or contribution of any other contributing persons. If the owner or operator does not disclose the information prior to the owner's or operator's formal appeal of a decision by the department, upon the department's request, the administrative hearing shall be continued for no more than thirty days from the scheduled hearing date. If who contributed to the contamination cannot be determined by a preponderance of evidence, or if an allocation for some or all of the contamination cannot be established by a preponderance of evidence, the liability that is not established to be the owner's or operator's by a preponderance of the evidence shall not be allocated to the owner or operator.
H. The department may issue a written interim decision or determination compelling owners and operators to allocate liability in accordance with section 49-1019, subsection D if either of the following conditions are met:
1. 1. The owners and operators agree that no other owners or operators are liable for the contamination.
2. 2. The contamination is from a single underground storage tank facility.