Ill. Admin. Code tit. 32, § 351.150
a) A licensee may perform well logging with a sealed source only after the licensee has a written agreement with the employing well owner or operator. This written agreement shall identify who will meet the following requirements:
3) Radiation monitoring required in Section 351.690(a).
5) If the sealed source is classified as irretrievable after reasonable efforts at recovery have been expended, the following requirements shall be implemented within 30 days:
i) The word "CAUTION";
iii) The date the source was abandoned;