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The area of review shall be defined as follows:
(a) Class II wells. The area of review for Class II permits and area permits shall be defined by a fixed radius as described in §146.6(b)(1) and (2) of this chapter except that the radius shall be one-half mile.
(b) Class I and III wells. The area of review for Class I and III wells are well fields which may be either:
(1) An area defined by a radius two and one-half miles from the well or well field; or
(2) An area one-quarter mile from the well or well field where the well field production at the times exceeds injection to produce a net withdrawal; or
(3) A suitable distance, not less than one-quarter mile, proposed by the owner or operator and approved by the Director based upon a mathematical calculation such as that found in §146.6(a)(2) of this chapter.