225 ILCS 705/33.10
An extension of the last preceding survey of every mine in active operation shall be made once in every 12 months and the results of the survey, with the date thereof, shall be promptly and accurately entered upon the original maps and all copies of the same, so as to show all changes in plan or new work in the mine, and all extensions of the old workings which have been made since the last preceding survey. The State mine inspector, the recorder, and the rescue station superintendent shall be furnished with a copy of the extended map or of the extension to the map. When the State mine inspector has corrected his copy of the original map, he shall deliver his copy of the extensions to said map to the Department which shall thereupon file the same or a photostat thereof in the archives of the Department. The former map or photostat thereof of any mine may be destroyed upon the filing of each last submitted map or copy provided the same is a complete map of the mine.
225 ILCS 705/33.10