; or (iii) except as provided in subparagraph (B)— (I) on the date that is 18 months after the date on which the Administrator granted the Good Samaritan permit, if the permitted work has not commenced by that date; or (II) if the grant of the Good Samaritan permit was the subject of a petition for judicial review, on the date that is 18 months after the date on which the judicial review, including any appeals, has concluded, if the permitted work has not commenced by that date. (B) Extension (i) In general If the Administrator is otherwise required to terminate a Good Samaritan permit under subparagraph (A)(iii), the Administrator may grant an extension of the Good Samaritan permit. (ii) Limitation Any extension granted under clause (i) shall be not more than 180 days for each extension. (4) Unforeseen circumstances (A) In general The recipient of a Good Samaritan permit or investigative sampling permit may seek to modify or terminate the Good Samaritan permit or investigative sampling permit to take into account any event or condition that— (i) significantly reduces the feasibility or significantly increases the cost of completing the remediation project that is the subject of the Good Samaritan permit or investigative sampling permit; (ii) was not— (I) reasonably contemplated by the recipient of the permit; or (II) taken into account in the remediation plan of the recipient of the permit; and (iii) is beyond the control of the recipient of the permit, as determined by the Administrator. (B) Termination (i) In general Subject to subsection (n)(3), the Administrator shall terminate a Good Samaritan permit or investigative sampling permit if— (I) the recipient of the permit seeks termination of the permit under subparagraph (A); (II) the factors described in subparagraph (A) are satisfied