Colorado Revised Statutes Title 8. Labor and Industry § 8-13-102. Eight-hour day--exceptions

(a) The operator of the underground mine, underground workings, or smelter establishes a work plan setting forth the terms and conditions under which the period of employment may exceed eight hours in a twenty-four-hour period; and

(b) The operator provides reasonable notice to its employees, except in cases of emergency or upset conditions, of proposed increases in the regular work schedule which would result in a period of employment in excess of eight hours in a twenty-four-hour period. Reasonable notice shall be construed to be not less than one week, during which time affected employees may comment.