(1) In reaching its decision, the department shall use:

(a) the information contained in the data base and inventory system provided for in ARM 17.24.1148;

(b) information provided by other governmental agencies;

(c) the detailed statement prepared under 82-4-228(3), MCA; and

(d) any other relevant information submitted during the comment period.

(2) A final written decision must be issued by the department including a statement of reasons, within 60 days of completion of the public hearing, or, if no public hearing is held, then within 12 months after receipt of the complete petition.   The department shall simultaneously send the decision by certified mail to the petitioner, every other party to the proceeding, and to the federal coal regulatory agency.