(1) "Hazardous site" means any geographic area located, in whole or in part, in the State of Arkansas, access to or use of which is determined by the Arkansas Department of Environmental Quality to be necessary or appropriate to implement a response ordered by the President of the United States;

(2) (A) "Hazardous substance" shall mean:

(i) Any substance designated pursuant to § 311(b)(2)(A) of the Federal Water Pollution Control Act;

(ii) Any element, compound, mixture, solution, or substance designated pursuant to § 102 of the Federal Water Pollution Control Act;

(iii) Any hazardous waste having the characteristics identified under or listed pursuant to § 3001 of the Solid Waste Disposal Act, but not including any waste the regulation of which under the Solid Waste Disposal Act has been suspended by act of Congress;

(iv) Any toxic pollutant listed under § 307(a) of the Federal Water Pollution Control Act;

(v) Any hazardous air pollutant listed under § 112 of the Clean Air Act; and

(vi) Any imminently hazardous chemical substance or mixture with respect to which the administrator has taken action pursuant to § 7 of the Toxic Substances Control Act.

(B) The term does not include petroleum, including crude oil or any fraction thereof which is not otherwise specifically listed or designated as a hazardous substance under subdivisions (2)(A)(i)-(2)(A)(vi) of this section, and the term does not include natural gas, natural gas liquids, liquefied natural gas, or synthetic gas usable for fuel, or mixtures of natural gas and such synthetic gas;

(3) "Passive-site owner" shall mean any person or entity owning any interest in any portion of a hazardous site, whether as owner, joint tenant, lessee, mortgagee, licensee, easement holder, mineral owner, or otherwise, and who has not entered into an agreement pursuant to 42 U.S.C. § 9622 for that site;

(4) "Response costs" shall mean all amounts of removal or remedial action, including any costs and expenses incurred as a result of contractor delays, and other necessary amounts, including attorney's fees and expenses reasonably incurred by any entity, including, but not limited to, the United States of America, the State of Arkansas, the governments of any other states, corporations, partnerships, and private citizens to investigate and secure a response action at a hazardous site; and

(5) "Settling party" shall mean any person who has entered into an agreement with the United States pursuant to 42 U.S.C. § 9622.