Section 57.22401 - Underground retorts (I-A and I-B mines)(a) Retorts shall be provided with-(1) Two independent power sources for main mine ventilation fans and those fans directly ventilating retort bulkheads, and for retort blowers, and provisions for switching promptly from one power source to the other; and(2) An alarm system for blower malfunctions and an evacuation plan to assure safety of personnel in the event of a failure.(b) Prior to the ignition of underground retorts, a written ignition and operation plan shall be submitted to the MSHA District Manager for the area in which the mine is located. The mine operator shall comply with all provisions of the retort plan. The retort plan shall include-(1) Acceptable levels of combustible gases and oxygen in retort off-gases during start-up and during burning; levels at which corrective action will be initiated; levels at which personnel will be removed from the retort areas, from the mine, and from endangered surface areas; and the conditions for reentering the mine;(2) Specification and locations of off-gas monitoring procedures and equipment;(3) Specifications for construction of retort bulkheads and seals, and their locations;(4) Procedures for ignition of a retort and for reignition following a shutdown; and(5) Details of area monitoring and alarm systems for hazardous gases and actions to be taken to assure safety of personnel.52 FR 24941, July 1, 1987, as amended at 52 FR 41397, Oct. 27, 1987; 60 FR 33723, June 29, 1995